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The present study demonstrates the vermistabilization of paper mill wastewater sludge (PMS) spiked with cow dung (CD) employing indigenous epigeic earthworm Perionyx excavatus Perrier. A total of six treatments were prepared along with a positive control (PC) and negative control (NC). Twenty earthworms were released into each treatment including PC and NC without earthworms. The different proportions viz., T1 (CD – 100%), T2 (PMS:CD – 1:3), T3 (PMS:CD – 1:2), T4 (PMS:CD – 1:1), T5 (PMS:CD – 3:1), T6 (PMS:CD – 2:1), PC (PMS – 100%) and NC (PMS – 100%) and changes in chemical parameters and microbial properties were recorded during the course of 60 days. Vermistabilization caused a significant decrease in the level of heavy metals: Cd (2.9–27.8%), Cu (0.22–42.3%), Pb (1.3–56.3%) and Cr (0.8–46.2%). The bioconcentration factor (BCFs) was also calculated and great amount of heavy metals accumulated in their body (mg kg−1) that ranged from 0.31 ± 0.003–0.45 ± 0.007 for Cd, 0.12 ± 0.005–0.24 ± 0.003 for Cu, 0.15 ± 0.005–0.31 ± 0.006 for Pb and 0.29 ± 0.007–0.56 ± 0.001 mg kg−1 for Cr, accumulation of heavy metals are in the order: Cr > Cd > Pb > Cu. The physicochemical parameters of earthworm treated substrate such as electrical conductivity, total nitrogen, total phosphorus and total potassium were significantly increased; whereas, pH, total organic carbon, C:N ratio (carbon: nitrogen) and C:P ratio (carbon: phosphorus) were reduced after 60 days of vermistabilization. The vermistabilized materials also had a higher population of bacteria (98.90 ± 0.30 CFU × 106 g−1), fungi (43.75 ± 0.55 CFU × 103 g−1) and actinomycetes (67.65 ± 0.45 CFU × 105 g−1) than initial mixtures. Moreover, several histopathological changes were observed in earthworm tissues viz., disintegration of cells, irregular surface of epidermis, cellular debris, irregular cellular compartmentation, and oval-shaped nucleus. Higher level of histopathological abnormalities was recorded in PC (PMS-100%) while none were detected in lower concentrations of PMS. Furthermore, the study concludes that the paper mill sludge in a mixture of cow dung (1:1 ratio) can be a useful proposition for utilizing this hazardous waste through the adoption of vermitechnology.

The results of physico-chemical analysis of pulp and paper mill effluent sedimented sludge revealed the presence of heavy metals (mg l−1) Fe (67.53), Zn (13.90), Cu (2.15), Cr (2.30), Cd (0.255), Mn (11.0), Ni (3.30), and Pb (1.05) along with persistent chlorolignin. The major persistent organic pollutants detected by GC–MS were ethane, 1,1-diethoxy; tetradecanoic acid; furane 2,5-dimethyl; n-hexadecanoic acid; nonacosane, trimethylenebis-1,3-dioxolane; 1,3-dioxolane, 2-(phynylmethyl). Twelve representative native plants were noted based on their population number growing on pulp and paper sludge and evaluated for their phytoextraction potential of heavy metals. The result revealed that Triticum aestivum was found as root accumulator for all metals except Cu. Similarly, the Brassica campestris accumulated all metals maximum in root except Ni, Fe and Pb. While, Eclipta alba accumulated majority of metals in their shoot and leaves, But Solanum nigrum, Rumex dentatus accumulated metals in root and shoot both. Rananculus scleratus accumulated all the tested metals in their aerial parts except Cd and Pb. Cammelina benghalensis accumulated metals in root except Cd, Pd. Similarly the Phragmites cummunis and Ricinus cummunis accumulated majority of metals in their shoot and leaves. It was also noted that several evaluated plant showed bioconcentration factor (BCF) greater than one for accumulated metals i.e. Pb in T. aestivum (1.285), C. benghalensis (5.142), Cannabis sativa (3.466), P. cummunis (7.180), R. cummunis (66.80) was also noted. Furthermore, greater than one translocation factor (TF) for all these plants showed strong evidence for phytoextraction and in situ remediation potential of these plants. The overall order of phytoextraction potential of native wetland plants were C. sativa > P. cummunis > C. benghalensis > T. aestivum > B. campestris > E. alba.

Heavy metal content has become a serious issue with increase in compost application in agricultural land. The bioavailable fraction (water soluble and diethylene triamine pentaacetic acid (DTPA) extractable) is the major concern comparing to the total concentration as it can be taken up by plants which in turn affects the human health. Thus, this study was carried out to determine the variation in bioavailable and leachable fraction of heavy metals (Cd, Cu, Fe, Ni, Pb, Cr, Zn, Hg and Mn) and to assess the influence of temperature, pH, organic matter degradation and humification during rotary drum composting of paper mill sludge (PMS) for 20 days. A total concentration of all the metals as well as nutrients increased during composting. The Hg was not detected in water soluble and DTPA extractable fraction, whereas Pb and Cr were also not detected in water soluble fraction in all the trials. A decreasing trend was observed in leachable quantity for all the metals during composting. Water extractable quantity increased for Fe and Cu during composting. Organic matter degradation and humification during composting influences the variation in bioavailability and leachability of heavy metals, which can be optimized by applying appropriate proportion of cow dung during rotary drum composting of PMS.

The efficiency of active aeration (AE) of constructed wetlands expressed as the ratio between implied oxygen consumption and oxygen delivered to the system is comprehensively reviewed in this paper. The aeration efficiency appears to be rather low with a mean value of 1.73% and median value of 0.48% of oxygen used in the systems for situations with only partial aerobic degradation of the pollutants. For full aerobic degradation, the mean value of AE is 3.74% but median value is much lower 1.08%. For both cases, the standard deviation is higher than the mean value (4.95% and 10.87% respectively), so there is a lot of variability in the data. For systems with the Forced Bed Aeration the results are more uniform and are close to the literature values given for this system, which is an implication that the proposed methodology might be potentially used for rough estimate of the aeration efficiency.

Management of industrial sludge is a big challenge for developing countries. Composting is an economical and viable option to manage and treat an industrial sludge. However, efficient compost production requires nature of materials involved, process understanding and physics behind the process. We investigated the physical parameters during composting of solid pulp and paper mill sludge in 550 L rotary drum composter. Variation in physical parameters such as bulk density, volatile solids, moisture content, free air space, void ratio, ash content and particle density were analyzed over the period of composting. Bulk density was observed increasing, whereas free air space was showed declining trend and observed 52% in end compost. The particle density was observed to be increasing from 610 to 680 kg m−3. End compost was analyzed for nutritional parameters and seen to be increasing over the period of composting. A strong relationship was found between various physical parameters. Pearson’s correlation coefficient matrix was formed between free air space, bulk density, moisture content and particle density.

In this paper, we analysed the pollutant removal efficiency and reliability of a vertical and horizontal flow hybrid constructed wetland (CW) planted with giant miscanthus and Jerusalem artichoke. The wastewater treatment plant, located in south-eastern Poland, treated domestic sewage at an average flow rate of 1.2 m3·d−1. The tests were carried out during. 5-years of operation of the sewage treatment plant (2011–2016). During this period, sewage samples were collected from three stages of wastewater treatment in four seasons (winter – February, spring – May, summer – August, and autumn – November). The following parameters were measured: BOD5, COD, total suspended solids, total nitrogen, and total phosphorus. The average effectiveness of organic pollutant removal expressed by BOD5 and COD was 98.8 and 97.6%, respectively, and the removal efficiency for total suspended solids was 93%. The average values of BOD5, COD, and total suspended solids in wastewater discharged to the receiver were significantly lower than the limit values required in Poland. The efficiency of total nitrogen and total phosphorus removal was 64.1 and 68.1%, respectively, and the average values of these components in the outflow from the treatment plant exceeded the standard levels. A reliability analysis performed using the Weibull probability model showed that the reliability of pollutant removal in the tested CW system was very high for BOD5 and COD (100%). It was also demonstrated that the tested CW did not provide effective elimination of biogenic elements (nitrogen and phosphorus), as evidenced by the low reliability values – 32 and 28%, respectively. The investigated hybrid CW system with giant miscanthus and Jerusalem artichoke removed organic and biogenic pollutants with a similar efficiency as systems using classic plant species such as reed and willow.

To date, the process of biodrying has been used for the drying of biodegradable waste materials to produce fuel. However, different applications other than incineration also exist for dried materials: e.g., sewage sludge could be used as a fertilizer. This paper investigates the potential of biodrying as a pretreatment method prior to the application of sewage sludge in agriculture. Experiments were performed in two biodrying reactors with operational volumes of 100 dm3 using two different aeration regimes to compare the efficiency of the two process alternatives: i) mesophilic conditions and ii) a full composting temperature profile including the thermophilic phase. The influence of the two different operating regimes on the elimination of pathogens and selected pharmaceuticals and personal care products (PPCPs) was investigated. Phospholipid fatty acid (PLFA) analysis was employed to identify the main groups of microorganisms responsible for the potential elimination of the detected micropollutants. The results showed that antibiotic activity was completely eliminated under both the operational regimes. Bisphenol-A (BPA) and irgasan (IRG) were detected in the untreated sludge, and the elimination efficiency for these substances was greater in the reactor with the mesophilic treatment (max. 88.3% for BPA and 47.7% for IRG) than under thermophilic conditions (60.1% for BPA and no significant removal of IRG). PLFA analysis indicates that Actinobacteria could be responsible for the biodegradation. Of the two indicator microorganisms used for the verification of the efficiency of the improvement in hygiene, only E. coli were completely eliminated under both regimes, while the enterococci content was reduced by 4 orders of magnitude. The results of this study document that the biodrying process possesses the potential for the removal of micropollutants from sewage sludge and might serve as a pretreatment process prior to using the treated sludge in agriculture.

The application of agricultural by-products as filter bed material for the treatment of oily wastewater is preferable due to their biodegradability and availability. The goal of this paper was to examine the sorption and filtration properties of sunflower (Lat. Helianthus annuus ) fibres in a raw state. SEM imaging and nitrogen adsorption at −196.15 °C were applied to evaluate sorbent morphology. FTIR spectroscopy was used to determine the chemical composition of the pith. Studies on sorption in static conditions (pith fragmentation 1.5–4.0 mm) allowed process kinetics to be specified. The experimental kinetics was fitted to pseudo first-order and pseudo second-order kinetics by a non-linear method. To better predict kinetic parameters, a new modified logistic equation was proposed. Sunflower fibre was found to have high oil sorption capacity (12.67 g/g) and good retention properties. During filtration experiments, an artificial reservoir brine (0.1, 2.0, and 20.0 g/l of oil) was used as an oil-in-water emulsion; sunflower pith was used as a filter medium. The influence of four process parameters (pH, bed height, initial oil concentration, and flow rate) on removal efficiency was studied. Oil concentrations were determined by gas chromatography. The results demonstrated that the prepared filters operated better at a lower pH, lower flow, a deeper bed material, and higher concentration of inlet oil. The filtration efficiency for the removal of crude oil from oily brines reached more than 99% in the initial stage of the process. The results obtained suggest that natural plant fibres can be an effective bed material to separate oil from oily brine.

Denitrifying bioreactors are simple, low-cost ecotechnologies designed to reduce nitrate (NO3−) present in septic tank effluent and drainage water. Recent studies indicate that, in addition to significant reduction in NO3− loads, these systems are also able to remove microbial contaminants from municipal wastewater. However, the removal of microbial contaminants in denitrifying bioreactors remains poorly characterised and factors that control removal in denitrifying bioreactors remain unexplored. In this study, the removal efficiency of faecal indicator bacteria Escherichia coli (E. coli) and total coliforms (TC) as a model for bacterial pathogens and F-specific RNA bacteriophage (FRNA bacteriophage) as a model for viruses was assessed for mesocosm-scale (∼700 L) bioreactors receiving municipal wastewater. Systems were filled with two different slow-release carbon sources: woodchip and coconut husk. The effect of media age on attenuation of microbial contaminants was assessed by comparing the performance of 8-year old systems with equivalent newly constructed woodchip and coconut husk bioreactors. Additionally, removal performance of these carbon substrates was compared to that of gravel, a non-carbon substrate commonly used in subsurface flow (SSF) constructed wetlands. Substantial reduction of E. coli, TC and FRNA bacteriophage from primary treated municipal wastewater was achieved in all bioreactors. Mean annual log10 removal efficiencies were similar between microbial indicators ranging from 1.4 to 1.9 for TC, 1.3 to 1.8 for E. coli and 1.3 to 2.0 for FRNA bacteriophage. All denitrifying bioreactors showed consistent year-round performance and long-term performance which did not markedly change in the ninth year of operation. The woodchip or coconut husk bioreactors achieved microbial effluent quality within the same range of log10 removal rates achieved in gravel-based systems. This suggests that denitrifying bioreactors, as well as reducing N loads, can effectively reduce microbial contaminants in wastewater, providing a complimentary disinfection role. Further research is needed to increase understanding of factors affecting removal of microbial contaminants in denitrifying bioreactors to support design of these systems for microbial contaminant removal.

The current study was carried out to test the removal of nitrogen and phosphorus from olive mill wastewater (OMW) by combination of sand filter and a mixture of aquatic plants ( Phragmites australis , Typha latifolia and Arundo donax ). The experimental pilot was composed of two serial systems: sand filter followed by vertical flow constructed wetlands (VF-CWs). The sand filter was filled with 50 cm of sand and 10 cm of gravel in the top and the bottom of the filter. The second step of the treatment consists of a tank (1 × 1 × 1 m 3 ) filled with 20 cm of gravel and 60 cm of soil, planted with a mixture of aquatic plants at a density of 8 young plants/m 2 for each plant and irrigated twice in the week by 20L of preliminary filtered OMW. During all experiment, OMW was diluted with domestic wastewater at a ration 1/1 (v/v). Mean diluted OMW concentrations were 2.05 g/L, 1.52 g/L, 1.94 mg/L, 1.70 mg/L, 0.22 g/L, 0.30 g/L, 26.78 g/L and 20.47 g/L for TKN-N, NH 4 + -N, NO 2 − -N, NO 3 − N, ortho-phosphate (OP), Total phosphorus (PT) total COD and dissolved COD respectively. Despite the rather high influent concentrations, the performance of the sand filter was very effective since it achieved average removals of about 60.4%, 74.4%, 80.61%, 97.85%, 96.45%, 79.75% and 76.75% for NTK, NH 4 + , NO 3 − , PO 4 3− , PT total COD and dissolved COD respectively. The presence of aquatic plants was more efficient in removing of nutrients and organic load. The average elimination of experimental system (sand filter + VF-CWs) in terms of flow was 62.48% for NTK, 90.43% for NH 4 + , 77.25% for NO 3 − , 98.51% for PO 4 3− , 97.53% for PT and 99.05% for total COD. In general, this study shows potential application of the experimental system to achieve nutrient and COD removal from OMW. Although the percent removal of organic matter and nutrients from OMW was very high, final OMW concentrations remained high, thus preventing their use for irrigation or immediate disposal into the environment.

Three parallel mineral filters, each with a volume of 2550 cm3, were used for phosphate removal from natural swimming pool (NSP) water. Filters worked continuously in saturated conditions. Hydraulic loading rates (HLRs) were 15 m3/m2h, 15 m3/m2d and 5 m3/m2d for Filter 1 (F1), Filter 2 (F2) and Filter 3 (F3), respectively. In the middle of the length of the filter, an inspection hole was located for sampling the filtration material. Samples were collected on the 55th, 87th and 120th day of filter operation. The phosphate sorption capacity of materials sampled from the filters was significantly lower than the sorption capacity of the fresh material, with their values varying between filters (different HLRs) and sampling events. In the case of F3 (slow filter), a decreasing phosphate sorption capacity was observed along with the time of operation. However, filtration material sampled from filters F1 and F2 had a higher P sorption capacity at the end of the monitoring period (day 120th day) than at the time of second sampling (day 87th day). This may suggest that the biofilm which developed on the grains of the filter blocked the contact between reactive material (RM) and treated water. Breaking the biofilm due to a faster flow (F1 and F2) resulted in increased filter sorption capacity. The remaining material sampled from F1, F2 and F3 was dried and also tested for P sorption capacity. Results showed that air drying increased the P sorption capacity of material from below 50% up to 100% of initial value, which suggests that periodic drying of filters may be a simple option for the regeneration of filtration material. P-bounded forms in filters were also analysed and discussed.

A novel integrated system consisted of microbial fuel cell, aerobic bioreactor, and anoxic bioreactor (MFC-AB-ANB) was designed and constructed to investigate its potential for the treatment of slaughterhouses wastewater associated with power generation and nitrogen recovery. A biocathodic tubular type MFC was used in this study and was inoculated with freshly collected activated sludge. The MFC-AB-ANB system was continuously operated for 163 days. The results revealed that maximum efficiencies of COD removal, ammonium oxidation, nitrate reduction, nitrogen recovery, Columbic efficiency, and power generation were 99%, 99.3%, 100%, 100%, 13.37% and 162.55 mW/m2, respectively. A mathematical model was developed based on Nernst–Monod model coupled with nitrification-denitrification model to predicate and describe the removal of COD, ammonium, and nitrate during continuous operation of the system. Significant agreement between the predicted and experimental results was observed for the removal of COD, ammonium, nitrate, and power generation with determination coefficients of 0.9750, 0.95675, 0.95499, and 0.89897, respectively.

Aquaponics is the integration of recirculating aquaculture and hydroponic systems which is considered to be an innovative, eco-friendly and sustainable food production technology. In this study, a special design of hydroponic biofilter that integrated constructed wetlands and floating-raft rice hydroponics was constructed to treat the nutrient rich effluents from the intensive fishpond and to establish an aquaponic system on pond scale. The treatment efficiencies and food production potential of the new rice hydroponic biofilter was evaluated after determining the key operating parameters. As the results, overall nutrient removal efficiency was optimized at hydraulic load rate (HLR) of 0.58 m.d−1 and air-to-water ratio of 2:1. The average removal efficiencies of total ammonia nitrogen (TAN), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (CODMn) from fishpond wastewater were in the range of 33.75–34.31%, 59.21–64.53%, 68.43–73.75% and 71.66–74.37%, respectively. Meanwhile, hydroponic rice grew well in the biofilter and gained a yield of 7 127 kg.ha−1. These results probably implied that the novel rice hydroponic biofilter exhibited efficient effluent treatment and presented as a viable alternative for the food production in a pond-scale aquaponics recirculating system.

Wood particle biofilters are being used for remediation of nitrate in watercourses but so far, have received little attention for the possibility of phosphorus (P) treatment. Phosphorus export in many agriculture and urban stressed watercourses however, is dominated by particulate rather than dissolved P and particulate P is potentially treatable by physical filtration. Five low cost, highly permeable media types, including woodchips, sawdust, bark mulch, corn cob chips and peastone, were tested in eight pilot scale biofilters over a six month period for their ability to remove suspended solids (TSS) and particulate P from turbid stream water. The biofilters were operated at high loading rates, with retention times averaging 1.9–4.2 h and achieved TSS removal averaging 85–97%. Excluding a 30 day startup period, seven of the eight biofilters removed an average of 53–64% of stream total P (TP) averaging 65.6 µg/L. The corn cob media provided lower TP removal (1%) because P leached from the media. These filters provided TP removal at hydraulic loading rates that were an order of magnitude higher than when similar media is used for nitrate remediation. These low cost filter media, with capacity for high loading rates, could offer a practical solution for P removal in urban storm water ponds, sewage lagoons and agriculturally impacted water courses.

Nowadays swine slurry management is a very important environmental issue. Sludge treatment reed bed systems are sludge treatment systems based on constructed wetlands. The present study characterizes via 16S rRNA gene high-throughput the bacterial communities contained in untreated swine slurry and treated swine slurry by means of mesocosm-scale sludge treatment reed beds receiving different slurry loadings. The bacterial community composition varied between the treated and untreated slurry, with a notable slurry loading influence also observed. Richness, diversity and ordination measurements of the studied communities evidenced profound differences between the untreated and treated swine slurry bacterial communities; and only slight differences among the treated swine slurry communities. Interestingly, the slurry loading allowed to define two groups: mesocosm communities residing in the highest hydraulic slurry loadings and other mesocosm communities. The pH value emerged as an important community composition, diversity and ordination predictor. The functional bacterial community composition was predicted through the in silico approach. Results confirmed that the main nitrogen cycle metabolic pathways were present in the mesocosm communities with ammonification and assimilatory nitrate reduction as the most commonly detected nitrogen pathways in treated swine slurry.

A prototype artificial wetland was designed to treat greywaters from the community of El Carrizo in Durango, Mexico, to remove the surfactants derived from used detergents. For this study, 6″ PVC tubes with a water depth of 40 cm were used, in which the water was replaced after 3, 8 and 15 days. Tezontle, gravel and agave fibre were used as supports, and Schoenoplectus americanus, which is an emergent aquatic plant, was used as biological material. The different levels of the factors resulted in 24 treatments, whose differences were validated with a factorial ANOVA of 4 × 2 × 3 with three repetitions. At the beginning and end of each period, it was determined the removal of detergents, oils and grease, total solids, total volatile solids, total suspended solids, changes in pH and electrical conductivity and toxicity of the effluent through bioassays with lettuce seeds. The results show that the best percentage removal of detergents (surfactants linear alkylbenzene sulfonates, LAS) of 90% was obtained with the agave fibre, with or without S. americanus, at a hydraulic residence time of 15 days; however, the treated water showed low seed germination indexes. This was followed by the gravel-S. americanus system, which had a removal percentage of 78% and showed decreases in all of the measured parameters and the lowest toxicity value on germination and root growth of Lactuca sativa. These characteristics define the optimal parameters for the implementation of artificial wetlands in the community of El Carrizo, Durango, Dgo., Mexico.

Since their inception in larger pond systems, the focus of anaerobic ponds has shifted from solids removal to optimising biogas production and reducing physical footprint to minimise land requirements. In this study, a horizontally baffled (HBAP) and vertically baffled (VBAP) anaerobic pond were compared. Distinct differences in the removal efficiency of COD fractions were observed, with particulate COD removal of 78% and 32%, and soluble COD removal of −26% and 19% in the HBAP and VBAP, respectively. A staged pond (SAP) was constructed through an HBAP placed upstream of a VBAP, with an additional HBAP used as a control (CAP). The SAP demonstrated superior biogas recovery potential over the control: methane production by the conclusion of the study was 6.09 and 9.04 LCH4 m−3 wastewater treated for the CAP and SAP, respectively. Methanogenic activity in the ponds was higher closer to the outlet, and hydrogenotrophic methanogenesis dominated over acetoclastic pathways.

A cost operative and favorable technology has been revealed for the removal of (COD, BOD and Oil & Grease) from oily industrial wastewater effluents. Batch scale studies for the biosorption potential of novel biosorbent Phragmites australis (Reeds). The study was supported at different constraints to obtain prime conditions of biosorbent dose, time of contact, pH, agitation speed and initial organic loads concentration. To dissect the propriety of the procedure and decided amount of organic loads removal, Langmuir and Freundlich isotherms were connected. The ideal estimations of contact time and agitation speed were found at 120 min and 150 rpm respectively. The ideal biosorption limits were seen at pH 7. Both pseudo-first and pseudo-second order models were connected and it was discovered that information fitting best to the pseudo-second-arrange active model. The outcomes demonstrated that Phragmites australis was an empowering adsorbent for the biosorption treatment of oily derivatives industrial wastewater.

The paper discusses the effectiveness of removing ammonium ions and indicator bacteria from domestic sewage in a vertical flow filter filled with a plastic material (PET flakes). Preliminary research has shown the effectiveness of ammonium nitrogen removal at the value of 66.74%. Principal Component Analysis was used to determine the mechanism of the removal of indicator bacteria. Three principal components were identified and they were responsible for 78,2% of input data variability. PCA analysis showed, that the effectiveness of Escherichia coli removal depended mainly on the filtering mechanism. In the case of coliform bacteria removal an additional factor was acidic conditions. A decrease in CFU of the coliform bacteria by one order of magnitude was observed at pH = 4.1.

In this study, wastewater blended from textile, distillery, and domestic sources at a corresponding volumetric ratio of 3:1:18, was treated using Lemna minor and Azolla filiculoides for 28 days in a batch system installed in a shade house. Analysis of variance between the two macrophytes showed no statistical differences in removals of all tested parameters (p

To demonstrate the feasibility of Enhanced Pond and Wetland (EPW) system for the treatment of Biological Trickling Filter (BTF) effluent, pilot-scale EPW systems were installed and operated in New Zealand climate conditions. The system consisted of: two High Rate Algal Ponds (HRAPs) followed by gravity Algal Harvesters (AHs), two Surface Flow Constructed Wetlands (SFCWs), and a Woodchip Denitrification Filter (WDF). The wastewater treatment performance of each treatment component was monitored fortnightly over six months (late autumn to winter) in terms of TSS, total and soluble BOD5, nutrients (N and P) and E. coli removal. Algal biomass production, algal harvest efficiency, and algal dominance in the HRAPs were also determined. The pilot-scale system maintained low final effluent TSS and BOD5 concentrations below 5 and 8 mg L−1 respectively, and achieved high removal of nitrogen (NH4-N: ∼95%; NO3-N: 77%), phosphorus (DRP: ∼65%) and E. coli (at least 3-log E. coli removal) throughout the experimental period. Particularly in autumn, the HRAPs achieved almost complete removal of both NH4-N (5.0 to

The need to expand marine fish production and improve the economic viability and sustainability of recirculating aquaculture systems led to the development of a zero-discharge, marine aquaponic system. In this study, water treatment capacity, nutrient cycling, and biomass production were evaluated in a prototype, commercial-scale marine aquaponic system that included a moving bed bioreactor (MBBR) for nitrification, a sand filter for solids removal and denitrification, and hydroponic plant beds. Red drum (Sciaenops ocellatus), two species of edible halophytes sea purslane (Sesuvium portulacastrum) and saltwort (Batis maritima), and organic solids, were successfully produced over a 9-month period. Extensive analysis of solids, organic matter, and nutrients (nitrogen and phosphorous) in water and plant biomass was used to develop detailed mass balances on the system. Simultaneous operation of the moving bed bioreactor (MBBR) and plant beds resulted in high ammonia removal rates, allowing the system to support a high fish biomass density (38.8 kg/m3). Passive denitrification was the main nitrate removal mechanism, contributing to approximately 59% of aqueous nitrogen removal. Conversion of a sand filter to a side-stream denitrification reactor resulted in removal of 17% of the daily aqueous nitrogen load and prevented nitrate accumulation in the system. In addition to fish and edible halophyte production, 34 kg of organic solids were harvested from the sand filter and provided to a commercial nursery that used the solids as a fertilizer. This study demonstrates that marine aquaponics is an effective way to simultaneously produce marine fish, edible halophytes, and fertilizer. Addition of biological MBBR and a denitrifying sand filter was shown to be beneficial in situations where there are space limitations for plant growth, unexpected plant losses, or to support high densities of fish.

Woodchip bioreactors are recognized as an effective best management practice in the Iowa Nutrient Reduction Strategy. This edge-of-field practice intercepts and removes NO3-N, thereby reducing the NO3-N concentration in tile drainage before being discharged into surface water. Actual NO3-N load reductions realized by woodchip bioreactors are impacted by bioreactor size, hydraulic retention time (HRT), and denitrification efficiency. A typical woodchip bioreactor in Iowa may have 0.07% bioreactor area with respect to treatment area, 4–8 h HRT, and 43% mean denitrification efficiency. Here, we explored the potential of using electrically stimulated woodchip bioreactors to achieve greater NO3-N removal, and estimated the costs of this approach. Batch experiments were conducted to determine the denitrification efficiency of electrically stimulated and traditional woodchip bioreactors at different HRTs and current densities. The resulting data was used to model costs and denitrification efficiency in 75 scenarios, covering a range of bioreactor volumes, HRTs, current densities, and annual durations of electrical stimulation periods. For each scenario, we reported the estimated annual NO3-N load reduction and NO3-N removal cost. We found that electrically stimulated woodchip bioreactors may remove an additional 37–72% annual NO3-N load than a traditional woodchip bioreactor, but at the expense of higher NO3-N removal costs, which were increased by 138–194%.

Among different decentralized wastewater treatment systems, constructed wetlands are particularly robust, reliable and cost-effective technologies. However, traditional treatment wetland designs have a limited capacity to remove total nitrogen. The recirculating vertical-flow constructed wetland (RVFCW) system is a novel modification of the vertical flow wetland (VFW), allowing for increased denitrification by circulating the nitrified effluent back into a recirculation tank, where it is mixed with primary treated wastewater. Microcosm experiments were conducted to investigate the effects on nitrogen removal of mixing recirculated VFW effluent with raw wastewater after different degrees of primary treatment, with and without attached growth media. The results show that the inclusion of attached growth media in the first chamber of the recirculation tank resulted in enhanced total nitrogen removal. The microcosms that contained a mixture of raw wastewater and VFW effluent showed denitrification efficiency of 83% after 48 h of contact time. An increase in the denitrification efficiency (up to 99.5%) was observed in microcosms that also contained attached growth media. The majority of nitrate-N (NO3-N) removal was achieved in the first 24 h. Inclusion of media increased the denitrification efficiency after 48 h contact time from 36 to 93% and from 31 to 88% in microcosms containing VFW effluent mixed at a ratio of 3:1 with wastewater after 1 and 2 days residence time in a septic tank respectively. It was inferred that the lower the degree of pre-treatment of wastewater into which the recirculated VFW effluent was mixed, the greater is the denitrification rate and thereby the lower TN concentration in the effluent.

This study attempted to determine an efficient flocculant that was used for the recovery of microalgal species, namely Scenedesmus. The biomass was grown in a pilot-scale raceway pond receiving domestic wastewater discharges. The microalgae achieved treatment efficiencies of 76.5% NH4+-N, 83.1% PO43−-P, 73.9% biological oxygen demand (BOD), and 42.8% chemical oxygen demand (COD). During microalgal harvesting, the highest biomass recoveries of 99.0%, 97.5%, and 96.5% were obtained by alum 300 mg/L at pH 7, chitosan 100 mg/L at pH 7, and cationic polymer 10 mg/L at pH 10, respectively. The protein, carbohydrate, and lipid yields of polymer-harvested biomass were 28.0%, 12.4%, and 17.4% (dry cell weight), respectively, which were higher than those obtained when applying either alum or chitosan flocculants. Moreover, the cationic polymer provided no detrimental effects on the fractions of fatty acids derived from the harvested microalgal cells. The microalgal biomass subjected to flocculation by either polymer or chitosan were entire and intact, whereas the lysis of cells was noticed during the alum flocculation process.

The present research investigated the efficiency of an integrated system for the treatment of wastewaters generated at a rural property located in the city of Vera Cruz do Sul, southern Brazil. The integrated system was composed of an anaerobic unit (UASB/AB), 4 subsurface constructed wetlands (SSFCWs), and two photoreactors (UV-254 nm). The evaluation of the performance was based on the reduction of the load parameters and mainly on the detoxification of the wastewaters. The ecotoxicological analysis included short-term assays with the microcrustacean Daphnia magna whereas the cytogenetic potential of the wastewaters was assessed by using the Allium cepa test system. On the one hand, the raw wastewaters presented a strong pollution potential due to high COD, BOD5, TKN, N-NH3 and total P values. On the other hand, the effluents treated by the integrated system showed high reductions of the abovementioned parameters and fully attend the Brazilian and International legal requirements. Furthermore, the treated wastewaters presented a complete absence of the acute ecotoxicity (100%) as well as significant reductions of the cytotoxicity, genotoxicity, and mutagenicity when compared to the raw wastewaters. Therefore, the investigated system can be considered an interesting low-cost sanitation alternative, especially for wastewaters produced in rural areas, where decentralized systems are more suitable. Besides, the results obtained in the present work demonstrate the importance of including toxicity analysis in the monitoring of waters and wastewaters in order to obtain a broader evaluation concerning the efficiency of different treatment systems.

The main aim of our study was to construct a two-stage vertical flow constructed wetland (VFCW) system to treat single household raw sewage water in India under tropical climate. For selecting the plant species different sets of lab experiments were carried out. Two different plant species (Typha angustata and Canna indica) were considered for their nutrient removal efficiency and biochemical methane potential (BMP) efficiency. Drum experiments were conducted to select the most suitable species for the constructed wetland. Batch assays were conducted in 100 ml bottles in order to determine BMP of plant biomass. The overall nutrient removal efficiency was the same in case of both the plant species that were tested. Typha angustata had been selected for planting in the single household wetland system as it is found in the natural wetlands of Goa and they have higher BMP than other species. The nutrient removal of pilot scale VFCW was monitored at two hydraulic loadings at 0.150 m/day and at 0.225 m/day. The removal of Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Kjeldahl Nitrogen (TKN), Ammoniacal Nitrogen (NH3-N), Total Phosphorous (TP), Total Dissolved Solid (TDS) and Total Volatile Solids (TVS) at 1st stage was 64%, 65%, 15%, 21%, 34% and 54% and for the 2nd stage reactor it is 90%, 88%, 50%,52%, 58% and 71% respectively on an average. After changing HLR (hydraulic loading rate) to 0.225 m/day the removal of COD, BOD, TDS, TVS, TKN and NH3-N at 1st stage was 61%, 62%, 33%, 40%, 35% and 58% and for the 2nd stage reactor it is 90%, 84%, 61%, 64%, 47% and 82% respectively on an average. As the loading rate increases there is no change in the treatment efficiency of TKN and NH3-N treatment efficiency increases. However marginal decrease in the treatment efficiency of COD and BOD of the system was observed. The overall footprint of the system got reduced from 1.5 m2 per person to 0.79 m2 per person under Goan climatic conditions.

Green roofs are a key component to building sustainable cities because of their multiple environmental benefits, but without the proper level of care, the leachate from green roofs might contain pollutants and become a new nonpoint pollution source in urban areas. Because its leachate quality is affected by the substrates and plants used, the objective of this study is to evaluate the effects of the substrates and plants with the aim of improving green roof applications. This study tested 3 materials – normal cultivated (C) substrate, commercial green roof (L) substrate, and mixed C and recycled glass (R) substrate – with a focus on using recycled glass materials in the green roof system. Recycled glass is a lightweight and porous material that improves pollutant absorption and water quality purification. Three different types of plants were tested: a sedum, a fern, and a shrub. Therefore, this study evaluated 9 combinations, each with 3 replicates. The differences in the substrates exerted significant effects on the chemical oxygen demand (COD) and phosphorous (P) concentrations. The nitrogen (N) concentrations were affected by differences in both the substrates and the plants. The changes in the observed water quality with time implied that compact substrates and mature plants reduced pollutant concentrations, except for N concentrations, in the outflow. The L substrate contained high levels of nutrients, and the plants grew better in this substrate than in the other two substrates; however, the L substrate also produced higher pollution concentrations. The R substrate, with recycled glass, performed well in the neutralization of acid rain but did not significantly reduce the levels of other pollutants. To enhance the purification ability of the recycled glass, the mixing ratio between the recycled glass and organic substances and the placement in the substrate are important factors.

Woodchip denitrification bioreactors are an important edge-of-field practice for treating agricultural drainage; however, their ability to filter microbial pollutants has primarily been explored in the context of wastewater treatment. Upflow column reactors were constructed and tested for E. coli, Salmonella, NO3-N, and dissolved reactive phosphorus (DRP) at hydraulic retention times (HRTs) of 12 and 24 h and at controlled temperatures of 10 and 21.5 °C. Influent solution was spiked to 30 mg L−1 NO3-N, 2–8 × 105 E. coli and Salmonella, and 0.1 mg L−1 DRP. Microbial removal was consistently observed with removal ranging from 75 to 78% reduction at 10 °C and 90–96% at 21.5 °C. The concentration reduction ranged from 2.75 to 9.03 × 104 for both organisms. HRT had less impact on microbial removal than temperature and thus further investigation of removal under lower HRTs is warranted. Nitrate concentrations averaged 96% reduction (with load removal of 14.6 g N m−3 d−1) from 21.5 °C columns at 24 HRT and 29% reduction (with load removal of 8.8 g N m−3 d−1) from 10 °C columns at 12 HRT. DRP removal was likely temporary due to microbial uptake. While potential for removal of E. coli and Salmonella by woodchip bioreactors is demonstrated, system design will need to be considered. High concentrations of these microbial contaminants are likely to occur during peak flows, when bypass flow may be occurring. The results of this study show that woodchip bioreactors operated for nitrate removal have a secondary benefit through the removal of enteric bacteria.

A single chamber membrane-less air cathode microbial fuel cell coupled constructed wetland (MFC-CW) was constructed to treat nitrobenzene-containing wastewater and generate electricity simultaneously. Three devices of blank control (CK), microbial fuel cell (MFC) and MFC-CW were investigated. The inherent relationship between substrate degradation and electricity generation were evaluated by the electronic characteristics. The maximum voltage of MFC-CW was obtained at the electrode spacing of 13 cm. The maximum power density of MFC and MFC-CW were 0.59 and 1.53 mW/m2 respectively. The maximum nitrobenzene removal rate of 92.89% was attained in the MFC-CW when the concentration ratio of nitrobenzene to chemical oxygen demand (COD) was 1:16 with hydraulic retention time at 24 h. The COD removal rate was between 67.92% and 78.30%, and the MFC-CW was efficient for COD degradation.

Water with excessive nutrients are continuously released into water bodies, the resulting eutrophication causes public health, environmental, and economic problems. Phosphorus (P) impairment of fresh surface waters is a major concern in the USA and worldwide. The aim of this study is to use a bench scale P removal system that utilizes electrocoagulation (EC) to address this water quality problem. This study examined the effects of treatment parameters (initial pH, initial conductivity, power input, and initial P concentration) on the ability of the EC process to remove P in solutions with initial P concentrations less than 2 mg/L. It also investigated the ability of EC to reduce concentrations of P in surface water and treated wastewater. P concentrations in phosphate solutions, surface water, and wastewater effluent were reduced by 99% in under 60 min. The removal efficiency was demonstrated to be directly proportional to the conductivity and power supplied.

Sustainable stormwater treatment systems remove pollutants using low energy, low maintenance and low cost solutions. Inactivation due to biotic stressors is one of the processes that govern the removal of faecal microorganisms in these systems. One such stress is the possible production of antimicrobial compounds by plants growing in sustainable stormwater treatment systems, potentially enhancing the removal of faecal pathogens. To this end, this study has investigated the antimicrobial potential of 17 Australian native plant species that are suitable for application in these systems but have not been tested for their antimicrobial activity within their seed exudates, seed extracts and/or seedling extracts. The extracts and exudates were tested using the agar well diffusion method. Nine of the selected plant species inhibited the growth of Escherichia coli. Among of the antibacterial plants, Melaleuca ericifolia, which has been previously applied in stormwater treatment systems, can be a suitable candidate for further study as it demonstrated antibacterial activity within all tested components. This species should be utilised in stormwater treatment facilities due to its effective nitrogen uptake, maintenance of hydraulic conductivity, and due to its potential effectiveness at inactivating microbial pathogens.

Pollution caused by wastewater is a serious problem in Algeria. This pollution has certainly harmful effects on the environment. In order to reduce the bad effects of these pollutants, many wastewater treatment processes, mainly physico chemical are implemented, In this case, the method most used is the physical-chemical coagulation-flocculation process. The procedure is based on the use of aluminium and iron salts alone or in combination with the use of two flocculants; the first one is a biodegradable natural bioflocculant Opuntia cactus juice, and the second is the synthetic hydroxyapatite; to treat waste water collected at the entrance of the treatment plant, in the town of Saida. The flocculants were characterized using Fourier transform infrared spectroscopy, The influence of various experimental parameters, such as the amounts of coagulants and flocculants used, pH, turbidity, COD and BOD5, was investigated. The coagulation—flocculation jar tests of wastewater reveal that ferric chloride, containing a mass of 0.3 g hydroxyapatite is the most effective adjuvant in clarifying the wastewater, with turbidity equal to 98.16%. In the presence of the two bioflocculants, Opuntia cactus juice and aluminum sulphate, with a dose of 0.2 g, flocculation is good, with turbidity equal to 95.61%. The examination of the main parameters studied during the flocculation tests shows that the degree of pollution decreases, this is confirmed by the COD and the turbidity values. Analysis of these results suggests the use of these flocculants in wastewater treatment.

Biosorption of heavy metals by seaweeds (marine macroalgae) is a potential environmental biotechnology technique for biotreatment of industrial effluents. However, the co-application of biomasses of different seaweeds for bioremoval of these inorganic pollutants from aqueous phase is very limited. In this study, for the first time, a coastal seaweed community composed of Chaetomorpha sp., Polysiphonia sp., Ulva sp. and Cystoseira sp. species harvested from the north coast of Turkey was first treated with sodium hydroxide and then used as natural biosorbent material for the bioremediation of zinc-containing synthetic wastewater. Batch biosorption experiments were performed to optimize the conditions of environmental parameters (pH, biosorbent quantity, heavy metal concentration and contact time). The biosorption capacity of biosorbent for zinc ions was highly affected by the operating conditions. Kinetic studies showed that the biosorption process was multistep, fast and diffusion controlled. The pseudo-second-order rate model well described the biosorption kinetics. The equilibrium data of zinc biosorption fitted best with Sips isotherm model and the maximum biosorption capacity of biosorbent from this model was calculated as 115.198 mg g−1. Thermodynamic parameters indicated that the biosorption process was physical and spontaneous. Besides, a single-stage batch biotreatment system was designed and the kinetic performance of this biosorption system was evaluated. The obtained results revealed that the prepared composite biosorbent could be used as efficient novel biosorbent for zinc removal from aqueous effluents.

This study attempts to achieve a high-rate nitrogen removal via the complete autotrophic nitrogen removal over nitrite (CANON) process in a modified single-stage tidal flow constructed wetland (TFCW) with step-feeding, and nitrogen transformation pathways in the TFCWs treating domestic wastewater were explored under shunt ratio constraints. Shunt ratio significantly affected nitrogen transformation pathways in the TFCWs throughout the experiment. The anammox bacteria were enriched most effectively at the shunt ratio of 1:1, and then the initiation of a CANON process was accomplished in the TFCW under the appropriate limited oxygen condition. The mean TN removal rate reached up to (127.00 ± 13.78) mg (L d)−1 correspondingly. It could be concluded that autotrophic nitrogen removal via CANON process developed in the TFCW with optimized microenvironment that developed as a result of appropriate shunt ratio. The optimal shunt ratio of the TFCW for nitrogen removal was 1:1.

Phragmites australis (PS) or common reed is one of the best-known herbaceous crops whose industrial potential is now being intensively reconsidered. The high yield and low input requirements make it a promising source for chemicals and biofuels. Besides, many studies have discussed its great potential as a renewable precursor with unique chemical composition for preparation of activated carbons (ACs) with high-grades. Thus, this article provided an overview of the different studies that used raw and activated PS as adsorbents for treatment of synthetic dyes and heavy metals. Adsorption isotherms, kinetics, and mechanisms of these pollutants were also reviewed. According to collected data, maximum Langmuir capacities of 58.82 and 33.0 mg/g were reported for dyes and metals on raw PS, compared to 526.32 and 53.71 mg/g on activated PS, respectively. ACs from PS biomass showed excellent performance for wastewater treatment, thus solving environmental problems of waste disposal and pollution control.

Loss of nitrogen (N) via ammonia (NH3) volatilization during composting of livestock manure causes nutrient imbalance in the compost. The effects of phosphogypsum (PG) and zeolite amendments on reducing N loss (via suppressing NH3 volatilization) and concurrent changes in carbon (C) and dry matter losses were investigated in a 100-day lab-scale mesophilic (27 °C) composting of cattle manure with rice hulls or sawdust as a bulking agent. The results showed that amendments PG and zeolite did not reduce NH3 volatilization but decreased total N loss, and when combined with sawdust the N loss was further reduced. However, the effects of PG and zeolite on reducing N loss were neither additive nor synergistic, and thus co-amending PG and zeolite did not further reduce N loss. The C and dry matter losses were smaller when sawdust was used as a bulking agent compared to rice hulls, and PG and zeolite amendments also decreased the C and dry matter losses in the presence of bulking agents. Combining sawdust as a bulking agent with either PG or zeolite amendments was more efficient than other combinations in reducing N, C, and dry matter loss in mesophilic composting of cattle manure.

Residual carbon and ammonium in municipal wastewater treatment plant (WWTP) tail water lead to membrane fouling, and prejudice the operation and life time of reverse osmosis (RO) membrane. In this study, a new combined treatment system of ozone oyster shells fix-bed bioreactor (OFBR)-membrane bioreactor (MBR) was developed and pilot scale was tested for 110 days to intensify the removal of residual carbon and ammonium in WWTP tail water. This results showed that the mean maximum COD, ammonium and TP removal efficiencies were achieved by 73%, 99% and 43%, under the optimum ozone dosage of 70 mg L−1 and HRT of 25 h. The single contribution of OFBR and MBR was 62% and 38% to COD removal, 94% and 6% to ammonium removal, 63% and 37% to TP removal, respectively. High throughput sequencing data showed that there were rich bacterial populations (>2800 species), and Deinococcus-Thermus, Firmicutes, Actinobacteria and Planctomyctes were dominant in both reactors. After addition of ozone, Deinococcus-Thermus and Planctomyctes species bacteria increased significantly in OFBR, and Firmicutes, Actinobacteria and Planctomyctes species bacteria increased remarkably in MBR, which might mainly contribute to carbon removal in OFBR and MBR, respectively. Aerobic ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and denitrifying bacteria were all existed in both reactors, which might be the main reasons for high removal efficiency of ammonium in OFBR-MBR system.

Effects of waste carbide sludge (CS) on microbial diversity and degradation of lignocellulosic fractions of mixed agricultural waste was experimented using a 550 L rotary drum composter. Four different trials of varying carbide sludge i.e. trial 1 (0%), trial 2 (1%), trial 3 (2%) and trial 4 (3%) was carried out for the study. The drum was turned every 24 h once to provide proper aeration and mixing of the waste materials for higher degradation and availability of organic matter to the microbial population. Hence with proper combination of waste materials and optimum addition of CS, a maximum of 31.56% reduction in Acid insoluble lignin (AIL), 46.03% of hemicellulose (HC) and 47.54% of cellulose (C) was observed in trial 2. The appropriate addition of CS was considered to increase the overall microbial activity of the composting process in trial 2. However, higher addition of CS in trial 3 and 4 was not effective in terms of higher degradation of volatile solids and also led to loss of organic nitrogen. In addition, it also increased the pH of compost to alkaline conditions and had a major effect on the growth of fungi. Pathogens i.e., Salmonella , Shigella was completely eliminated at the end of 20 days due to higher temperature and addition of waste carbide sludge in trial 2, 3 and 4 at the end of 20 days.

Wetlands have long played an important role as natural purification systems. Textile industry processes are among the most environmentally unsustainable industrial processes, because they produce coloured effluents in large quantities polluting water resources. In this study, two different azo dyes (Acid Blue 113 (AB113) and Basic Red 46 (BR46)) have been fed as part of synthetic wastewater recipes to a laboratory-scale vertical-flow construction wetland set-up comprising wetlands with gravel media as controls and wetlands planted with Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) for each dye. Two different concentrations (7 mg/l and 215 mg/l) were used for each dye at two different hydraulic retention times (48 h and 96 h). According to results for the low concentration of BR46, there is no significant ( p > 0.05) difference between wetlands (unplanted and planted) in terms of dye removal. The use of plants concerning the short contact time scenario for ammonia-nitrogen (NH 4 -N) and a low concentration of AB113 is linked to good removal. In case of low dye concentrations, the presence of plants for the long contact time scenario impacted significantly ( p 0.05) positive on the removal efficiencies of nutrients. For chemical oxygen demand (COD), the removal percentages were 50%, 59% and 67% for the control and for the wetlands with short and long retention times, respectively. All reductions were statistically significant ( p 0.05). For the high concentration of BR46, the removal percentages for this dye and COD were 94% and 82%, and 89% and 74% for the long and short retention times, respectively. For the low concentration of AB113, the percentage corresponding removals for the dye were 71%, 68% and 80%. The COD removals were 4%, 7% and 15% for the control, and the short and long retention times, respectively. Finally, for the high concentration of AB113, the percentage removals for the dye and COD were 71% and 73%, and 50% and 52% for the 48-h and 96-h retention times in this order.

Optimization of a vermifiltration process was made for hydraulic retention time (HRT), hydraulic loading rate (HLR) and recirculation ratio (R), organic loading rate (OLR), earthworm abundance and reactor type on organic matter removal from urban wastewater using a small-scale vermifiltration process comprising single stage, and four-stage vermifilter (VF) systems. All reactor modules were made of PVC with a total volume of 25 L using vermicompost as the filtering material and quartz sand and gravel as the inert filter. System performance was assessed by the removal efficiencies of BOD5, tCOD, sCOD, pCOD, TSS and NH4+. In the earthworm study, four abundances were evaluated: 10 g L-1 (W10), 20 g L-1 (W20), 30 g L-1 (W30) and 40 g L-1 (W40). In the four-stage VF the earthworm abundance evaluated was 20 g L-1. W20 proved to be the optimal treatment condition with efficiencies for BOD5, tCOD, pCOD, TSS and NH4+ of 97.5%, 74.3%, 91.1%, 98.2% and 88.1%, for a pCOD/tCOD ratio of 0.20. The four-stage sequential VF promoted a decrease of BOD5 (98.5%), tCOD (74.3%), pCOD (86.7%), TSS (96.6%), and NH4+ (99.1%). Results indicate that sequential VF systems can significantly improve treatment efficiencies when compared to single stage VF. (C) 2016 Elsevier B.V. All rights reserved. FUTURAMB(R)

To mitigate the detrimental risk of residual phenolic endocrine disrupting chemicals (PEDCs) from the discharge of sewage treatment plants (STPs) and to increase the utilization of constructed wetlands (CWs), both a stacked CW (SCW), comprising vertical and horizontal flow CWs, and an assembled bio-filter (ABF) were developed and their capability to remove PEDCs from STP discharge at high hydraulic loading rates (HLRs) of 0.5–2.0 m/d evaluated. The SCW and ABF showed different performance on PEDCs removal because of process structural difference. The removal percentages of PEDCs were associated with their octanol-water partition coefficients (LogKow), except 4-nonlyphenol (4-NP) whose apparent removal rate was affected by its precursors, and declined in the order of triclosan (TCS) at 80% and 69%, 4-t-octylphenol (4-t-OP) at 58% and 51%, estrone (E1) at 48% and 44%, and bisphenol-A (BPA) at 45% and 32% in the SCW and ABF systems on average, respectively. The efficiencies of SCW and ABF were superior to the single type of CWs, such as surface flow CW, vertical flow CW, and horizontal flow CW, in terms of removal rates or first-order removal rate constants. Recommended value of HLR for optimal utilization of SCW and ABF to ensure essential removal of PEDCs from STP discharge was between 1.5 and 2.0 m/d.

In the study, the effects of electrode material and substrate concentration on the bioelectricity generation and wastewater treatment performances in air-cathode microbial fuel cell coupled with constructed wetland (CW-ACMFC) systems were investigated. Four materials including carbon fiber felt (CFF), stainless steel mesh (SSM), graphite rod (GR), and foamed nickel (FN) were used as air-cathode and anode for each system. The obtained maximum power densities of Systems 1, 2, 3 and 4 were 4.80, 2.30, 3.35, and 5.11 mW m−2, respectively. In addition, a relative higher NO3-N removal efficiency was observed in four reactors, However, average COD removal percentages of Systems 1, 2, 3, and 4 were 42.30%, 37.42%, 48.78%, and 35.73%, respectively. The relative abundance of autotrophic denitrifying bacteria in the FN system was relatively higher. In summary, CFF and FN can be used as the electrode materials in the CW-ACMFCs system for wastewater treatment and bioelectricity generation simultaneously.

A laboratory-scale controlling internal circulation (CIC) anaerobic reactor was developed to treat cassava wastewater. The hydraulic retention time (HRT), internal circulation ratio, and temperature were selected as main operating variables that could be optimized to increase efficiency of the reactor. Responses of microbial communities to changes in these parameters were investigated using high throughput sequencing (HTS) approach. With increasing internal circulation ratio, the COD removal efficiencies and gas production rates also increased. On the other hand, decreasing temperature to 20 °C resulted to increase in the effluent COD concentration to 1000 mg L−1, with low gas production rate of 0.10 m3CH4 kg−1·COD−1. Upon starting the internal circle of the CIC reactor, species diversity was reduced while species abundance increased. Specifically, Methanosarcinales increased from 32.82% to 39.69%, and Methanobacteriales from 33.72% to 54.77%. However, when the CIC reactor temperature was further reduced to 25 °C, the abundance of Methanobacteria decreased to 33.35%. Results showed the microbial community shift was observed at different internal circulation ratio and temperature, influencing the pollutants removal rate and gas production rate.

Although the microalgae biomass is a significant feedstock for bioethanol production, studies on “third generation” of algal bioethanol is at its early stages of investigation. In this study halophilic microalgae Dunaliella sp. was used for producing bioethanol. Physical and physicochemical methods of pretreatment procedures were used. Some important parameters such as KNO3 (0–1000 mg/L), KH2PO4 (0–35 mg/L), MgSO4 (0–500 mg/L) nutrient amendments and NaCl (15%–30%) concentrations for Dunaliella sp. cultivation were optimized. Changing fermentation pH within 4–7 range, and yeast inoculum amount by inoculation of 0.5–3 ml volumes were used for optimization of the bioethanol production processes. Dilute acidic hydrolysis with 1% sulfuric acid in autoclave was found to be very effective in saccharifying algal biomass and higher bioethanol production values were obtained under nitrogen-depletion conditions. The highest bioethanol production by Saccharomyces cerevisiae was obtained at 72 h of incubation at substrate concentration of 30 g/L microalgal biomass and 3 ml inoculums at pH 6. The results demonstrated that at the optimized saccharification and fermentation conditions the bioethanol production could be increased up to 7.26 g/L, which was 10.7-fold higher than the value obtained by using the microalgal biomass was not exposed to any pretreatment. In the present study we showed that bioethanol production from biomass of a halophilic microalgae, which is known as a promising feedstock for bioethanol production, can be increased by appropriate pretreatments.

This research investigated the efficiency of a pumice stone biofilter tank for nitrogen removal from a recirculating aquaculture system. The pumice bottom substrate nitrification-denitrification tank was a glass tank packed with a 5 cm depth of pumice stone (approximately 3 mm in diameter) at the bottom. It was found that the pumice stone could perform as a nitrification biofilter under aerobic conditions. When applying methanol as the external carbon source at a COD:N ratio of 5:1 and then covering the tank with a plastic sheet to reduce gas exchange, pumice stone could remove nitrate through denitrification. Thereafter, nitrification and denitrification treatments using the pumice tank were applied to a 100 L moderate density (10 kg m −3 ) recirculating aquaculture system (RAS) under laboratory conditions. The RAS consisted of a 100 L tilapia culture tank connected to a 100 L pumice tank packed with a 5 cm layer of pumice stone. It was found that the nitrification treatment performed by the pumice tank could control ammonia and nitrite concentrations within the required safety range throughout the 121-day culture period. When nitrate accumulated to approximately 50 mg-N L −1 in water, water recirculation was paused, after which batch denitrification treatment was performed by adding methanol at COD:N of 5:1 in the pumice tank. With nitrification-denitrification treatment, ammonia and nitrite concentrations were below 1 mg-N L −1 and nitrate was kept below 50 mg-N L −1 while nitrate in the control tank was as high as 352.47 ± 9.67 mg-N L −1 . Moreover, the pumice bottom substrate tank with methanol supplement had no negative effect on growth and survival of fish in the recirculating system.

The feasibility of adding straws of ornamental flowers as carbon source into gravel-based biofilters to enhance removals of nitrate and sulfate simultaneously, and the concomitant adverse effects were evaluated in this study. The straws were added into a perforated PVC pipe vertically inserted into each biofilter. Results showed that compared to the control biofilter with almost no removal capacity, the experimental systems effectively co-eliminated nitrate and sulfate from the wastewater, with a mean removal rate of 1.29–2.11 g NO 3 − -N m −3 d −1 and 1.03–2.16 g SO 4 2− m −3 d −1 , and higher efficiencies achieved for carnation and lily straws than rose and violet. A significant positive correlation was detected between nitrate and sulfate removal efficiency, with the nitrate removal notably more efficient. Nitrate and sulfate removal rates both decreased gradually with the operation time due to the declining carbon supply, and could be augmented again by fresh straw addition even in winter season. The phosphorous removal capacity of the biofilter was low and just influenced limitedly by the straw addition. High contents of organic carbon and colored matter were determined in the effluent after the straw addition but sharp drops to low levels were followed, resulting in insufficient carbon source for the removals of nitrate and sulfate. Mild accumulations of nitrite and ammonium occurred, averaging 0.39–1.30 mg L −1 and 0.46–0.93 mg L −1 in the effluent, while the content of dissolved sulfide was low. The biofilter added with rose straw showed the lowest relative adverse effects despite of its low removal capacities, and good performance with moderate adverse effects were obtained when adding with the carnation straw. The biofilter can be potentially applied to co-alleviate nitrate and sulfate pollutions although further optimization of straw addition is still required.

In many arid regions, the reuse of wastewater is an economic option for crop irrigation. To avoid health risks for consumers, pathogens must be eliminated prior to application. Slow sand filtration (SSF) represents an effective low-tech treatment technology for pathogen removal from water. To further improve the time-space yield of SSF, innovative filter configurations were investigated regarding the removal of the pathogen indicators Escherichia coli , enterococci, Clostridium perfringens spores, somatic and F-specific RNA coliphages as well as heterotrophic bacteria. A standard filter ( N ), a recirculating filter ( R ), a static cascade ( N + N ) and a rotating cascade ( C ) were tested at high and low hydraulic loading rates, two recirculation rates and two rotation frequencies. Results showed that only C and N + N concurrently complied with European standards for E. coli and enterococci, achieving mean log removal of 2.7-4.7 and 2.1-2.4, respectively. The best performance was reached by C with weekly rotation; N + N may be a promising, technically simpler alternative. The crucial role of biological removal mechanisms for E. coli and enterococci elimination was indicated by (i) the increased efficiency of the standard SSF N after 1½ years of operation and (ii) the positive impact of several Schmutzdecke layers. C. perfringens spore removal performance was good for all SSFs. Considerable sorption of spores was indicated by decreased efficiency in N and C at long operation times. Somatic coliphages were reduced to concentrations close to the detection limit, while F-specific RNA coliphage removal was ∼1.1 log. Removal of heterotrophic bacteria was generally limited.

This research used an upflow zeolite-based biofilm reactor (UZBR) with rice washing drainage (RWD) as carbon source to improve denitrification efficiency and simultaneously treat RWD in the process. Removal performance in two UZBRs inoculated with and without activated sludge was investigated at different ratios of RWD to synthetic nitrate-contaminated groundwater (1/3 (v/v), 1/5.5 (v/v), 1/8 (v/v)). At optimum conditions (1/5.5 (v/v)), nitrate removal efficiencies reached 97.0% ± 2.0% with activated sludge and 98.2% ± 1.1% without activated sludge, and TOC concentration in RWD decreased by 80.6% ± 1.1% and 88.6% ± 3.9%, respectively. Illumina sequencing analysis revealed that the microbial community structures in the reactor with activated sludge differed with the reactor without the activated sludge. RWD itself generated polyphosphate accumulating organisms (PAOs) without the breeding of glycogen accumulating organisms (GAOs). Further, the read counts of denitrifiers were more at the bottom and middle of the reactor than at the top. It has been suggested that RWD could provide electron donors and denitrifiers for denitrification and simultaneously treat RWD on-site in a reactor.

Three distinct septic systems designed for onsite removal of nitrogen (N) from residential wastewater were installed at the Massachusetts Alternative Septic System Test Center (MASSTC) and at homes across Suffolk County (SC), New York. All configurations featured nitrifying sand beds coupled with denitrifying biofilters composed of 1) a lined, saturated sand and woodchip layer, 2) a saturated box filled with woodchips, or 3) an unlined, unsaturated sand and woodchip layer. Total N (TN) in final effluent discharge from the three systems at MASSTC over more than two years were 7.1 ± 7.8, 4.3 ± 4.2, and 6.9 ± 8.4 mg N L−1, respectively representing TN reductions of 83%, 87%, and 84% from influent TN. Systems at MASSTC also removed on average 90.0–99.9% of 10 of 11 organic contaminants in pharmaceutical and personal care products, microbes indicative of pathogens, and biochemical oxygen demand. Over periods up to 16 months from start-up, effluent from three lined, one woodchip box, and three unlined systems in SC averaged 8.3 ± 9.2, 5.3 ± 3.7, and 8.7 ± 4.9 mg-TN L−1 representing removal rates of 90%, 94%, and 88%, respectively. For all systems, wastewater N was effectively nitrified year-round; N removal varied seasonally as denitrification attenuated in winter. Substantial quantities of TN were removed in the sand beds, likely due to denitrification in anoxic micro-zones. While elevated levels of carbon leached from the wood-based biofilters installed at MASSTC during the first 60 days of operation, no substantial decline in dissolved organic carbon or N removal was observed between the first 15 months of operation and the following 12 months. Collectively, the performance of these non-proprietary, passive systems suggest they may be a useful alternative septic system for protection of groundwater from elevated levels of N, organic contaminants, and pathogens.