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Surface water and groundwater have been experiencing increasing risks of contamination in recent years because of the poor management of the immense amounts of waste created by different human activities. Inappropriate dump sites have served for many years as marginal disposal sites for a wide range of wastes, including solid waste, fresh sewage and hazardous waste, in developing nations such as Ethiopia. Physical, anthropogenic and organic procedures continuously interact to deteriorate the waste. One of the results of these practices is artificially contaminated leachate, which is potentially hazardous waste from disposal sites. If not managed appropriately, such a dumping site can contaminate groundwater (through leachates) and surface water (through contaminant transport by flooding and groundwater movement). Along these lines, this study focuses on the applications of water quality index in the ground and surface water quality caused by the waste disposal site of Bahir Dar city within the Chilanchil Abay during the study period. Water testing was performed on five samples of surface water and six samples of groundwater in each month from 30th March (dry season) to 20th August (wet season). More than 13 water quality parameters, for example, pH, TDS, electrical conductivity, turbidity, temperature, dissolved oxygen (DO), TH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), TC, NO3−, PO43−, Cr, Mn, and Pb contents, were examined in both ground and surface water. It was discovered that water quality status of the Chilanchil Abay watershed ranges from 15.87 to 36.6 for surface water and 42 to 46.2 for groundwater suggesting poor and marginal status for drinking water purpose.

Life Cycle Assessment was used to evaluate onsite wastewater treatment systems (OWTS): aerobic treatment unit (ATU) with reinforced concrete (C.ATU) and HDPE (H.ATU) tank; and constructed wetland (CW) with three biochar concentrations in the substrate (0%; 10, and 20% v:v), dubbed CW.BC0, CW.BC10 and CW.BC20, respectively. CML 2001 in SimaPro® was used to evaluate the impacts of the treatment of 1 m3 wastewater. The OWTS were compared on their overall environmental performance scores (OEP). ATUs have higher impacts on human toxicity, eutrophication, freshwater and marine ecotoxicity. The CW.BC20 has the lowest global warming impact (GWP) while CW.BC0 has the highest. Electricity consumption was the largest contributor to the impacts of the ATUs. PVC pipes, coir peat, geomembrane, and electronic devices were the biggest contributors to the impacts of the CWs. The OEP of the CWs were almost a third of the ATUs’ (6.07E-03). Changes in electricity sources were tested according to the 2030-Australian targets; increasing renewables share improves the OEP of ATUs by 39%; nevertheless, CWs continue to outperform the ATUs. Variations in biochar biodegradation had a small effect on the OEP of CWs; being relevant only to GWP. This study provides a reference to policy makers for better evaluation of OWTS. HIGHLIGHTS First to present comparative LCA of constructed wetlands vs aerated treatment units for onsite domestic wastewater treatment (OWTS).; Investigates the consequences of future changes in electricity generation on the environmental efficiency of OWTS.; Investigates the effect of construction material choice on the overall environmental performance of the systems (OEP).

A technical feasibility study was carried out at the wastewater treatment plant (WWTP) Hamm-West in 2018, which included preliminary planning for the improvement of the plant, using different advanced wastewater technologies. The results of the technical feasibility study show that the application of activated carbon or ozone, in combination with an additional filtration system, can not only remove organic micropollutants efficiently but can also significantly improve the quality of other standard parameters in the WWTP effluent. This technical feasibility study, along with seven other studies, is part of the module-based approach the Emschergenossenschaft and Lippeverband (EGLV) is pursuing in order to improve wastewater treatment plants with advanced treatment systems. Finally, the module-based approach can be used to pair the most suitable WWTPs with the best applicable technologies to improve the treatment process in the whole Lippe catchment area. HIGHLIGHTS Advanced wastewater treatment for organic micropollutants.; Module-based approach.; Wastewater and stormwater treatment plants.; Technical feasibility study.; Holistic approach.

The carwash is known as one of the most important urban services that brings about the production of huge volume of wastewater with high turbidity and high chemical oxygen demand (COD). Seasonal and carwash location features affect the quality of carwash wastewater. Various methods with special focus on chemical processes have been employed for carwash wastewater treatment and eliminating different pollutants from this wastewater of great concern for the environment. This review was conducted for identifying and comparing the efficiency of chemical processes for carwash wastewater treatment. To this aim, key words were identified and a search protocol was defined to search studies in three databases: Scopus, Web of Science, and PubMed. The results of this systematic review indicated that coagulation (66%) is the most common chemical processes for carwash wastewater treatment. Although chemical processes are able to reduce the turbidity and COD over 80%. Due to the characteristics of carwash wastewater, chemical processes are a necessary pretreatment for processes such as membrane technology. Rapid treatment and high efficiency are the advantages of wastewater treatment by chemical methods, but the energy consumption and sludge volume are two main factors in selection the chemical processes for carwash wastewater treatment. Highlights Considering the qualitative properties of carwash wastewater, the use of chemical processes requires pretreatment steps such as filtration and aeration.; Given the importance of suspended solids and turbidity in carwash wastewater, the coagulation process is the predominant chemical process employed in the studies (65%) for carwash wastewater treatment.

Two advanced control strategies were applied in the secondary and tertiary stages, respectively, of a full scale wastewater treatment plant (WWTP). This has a nominal capacity of 330,000 population equivalent (PE), a complex configuration (having been upgraded several times through the years), and it faces significant seasonal load fluctuations (being located in a touristic area, in Northern Italy). The lifting station of the tertiary treatments (devoted to phosphorus precipitation and UV disinfection) was optimized by adjusting the pumped flowrate, depending on influent phosphorus concentration. A preliminary simulation showed that a 15% reduction of pumping energy could be achieved. This result was confirmed by field measurements. Moreover, a fuzzy control system was designed and applied to one of the six parallel nitrification reactors, yielding a reduction of more than 25% of the power requirement for aeration. Overall, the combined application of the two controllers led to a 7% reduction of the total energy consumption of the plant. This result is particularly promising given that the fuzzy controller was applied only to one of six biological reactors. HIGHLIGHTS Smart control strategies are required for WWTPs: fuzzy logic was adopted for aeration.; Full scale demonstrations of control strategies are rarely described in the literature.; A significant energy demand reduction has been achieved in a real scale WWTP.; The potential of plant-wide application of combined control strategies has been demonstrated.; The designed controllers are highly adaptable, favouring applicability in other plants.

The fate of pathogen indicators (Escherichia coli – EC, intestinal enterococci – IE, RNA-F bacteriophages and spores of sulfite reducing bacteria – SSR) was extensively studied in Parisian large-scale wastewater treatment plants (WWTPs), based on conventional activated sludge, biofiltration or membrane bioreactor (MBR) processes. Between 14 and 87 campaigns were performed between 2014 and 2018 in five WWTPs. High removals of 3 log for both EC and IE, and lower removals of 1–2 log for SSR and RNA-F bacteriophages, were observed in conventional activated sludge and biofiltration WWTPs. The MBR WWTP achieves notably greater removals of 4.5–5.5 log for faecal bacteria and 3–4 log for SSR and RNA-F bacteriophages. This WWTP is the only one already in compliance with reuse standards, the other ones being non-compliant because of SSR and RNA-F bacteriophages. The implementation of a micro-grain activated carbon process would increase the WWTP removals of 0.8 log for faecal bacteria, due to particles retention, with no significant effect on both other pathogens. Ozonation (0.9–1.3 g O3/g dissolved organic carbon) or performic acid (0.8–1.2 ppm) would have greater benefits with additional removals of 1.5–2.5 log for EC, 1–2 log for IE and 0.5–1 log for SSR and RNA-F bacteriophages. Correlations between pathogen indicator removals and initial concentrations were found, as well as a significant decrease of RNA-F bacteriophage concentrations in Parisian raw wastewater, below 2 log. Thus, RNA-F bacteriophages could be a real issue to evaluate the compliance of Parisian wastewater with reuse. The time evolution of removals demonstrated that SSR is the most problematic parameter regarding reuse in conventional activated sludge and biofiltration WWTPs, as its initial concentration is high (5 log) but removals insufficient (

Understanding the microbial ecology of a system allows linking members of the community and their metabolic functions to the performance of the wastewater bioreactor. This study provided a comprehensive conceptual framework for microbial communities in wastewater treatment electro-bioreactors (EBRs). The model was based on data acquired from monitoring the effect of altering different bioreactor operational parameters, such as current density and hydraulic retention time, on the microbial communities of an EBR and its nutrient removal efficiency. The model was also based on the 16S rRNA gene high-throughput sequencing data analysis and bioreactor efficiency data. The collective data clearly demonstrated that applying various electric currents affected the microbial community composition and stability and the reactor efficiency in terms of chemical oxygen demand, N and P removals. Moreover, a schematic that recommends operating conditions that are tailored to the type of wastewater that needs to be treated based on the functional microbial communities enriched at specific operating conditions was suggested. In this study, a conceptual model as a simplified representation of the behavior of microbial communities in EBRs was developed. The proposed conceptual model can be used to predict how biological treatment of wastewater in EBRs can be improved by varying several operating conditions.

The effect of the lockdown imposed to limit the spread of SARS-CoV-2 in France between March 14 and May 11, 2020 on the wastewater characteristics of two large urban areas (with between 250,000 and 300,000 inhabitants) was studied. The number of outward and inward daily commuters was extracted from national census databases related to the population and their commuting habits. For urban area A, with the larger number of daily inward commuters (110,000, compared to 53,000 for B), lockdown was observed to have an effect on the monthly load averages of chemical oxygen demand, biochemical oxygen demand, total Kjeldahl nitrogen, total suspended solids and total phosphorus, all of which decreased (confidence level of 95%). This decrease, which varied between 20% and 40% and reached 45% for COD, can be related to the cessation of catering and activities such as hairdressing, which generate large amounts of graywater. The ammonium loads, due to the use of toilets before leaving for work and after returning from work, remained constant. In the case of urban area B, lockdown had no noticeable effect. More data would be necessary in the long term to analyze the effect of changes in the balance between ammonia and carbon sources on the operation of wastewater treatment plants.

Sludge dewatering is an important step for wastewater treatment. Composite degradable flocculant (CDF) was prepared by cationic polyacrylamide (PAM) grafting onto modified starch with a novel initiator, and characterized by Fourier transform infrared spectroscopy. The microstructure of flocculated sludge was characterized by scanning electron microscopy. The study investigated the properties of CDF compared to PAM, which showed that the prepared CDF exhibited a highly effective flocculation on sludge dewatering, a higher transmittance and chemical oxygen demand removal rate, and a lower value of effluent ammonia nitrogen and total phosphorus. The fermentation process was also analyzed by testing the performance of dewatered sludge (temperature, pH, ammonia nitrogen, E4/E6 (humic acid absorbance at 465 nm (E4) and 665 nm (E6))). The dehydrated sludge with CDF could be easily compressed into cakes by belt-filter for easy transportation and storage. With the continuous addition of CDF and PAM, the corresponding index of capillary suction time (CST) increased. Moreover, the total value of CST with CDF was low, showing a good dewaterability. In addition, the sludge index of pumping time and moisture content with CDF were low in contrast with PAM. Fermentation experiments demonstrated that sludge with CDF had a comparatively high temperature and low value of E4/E6. Such novel CDF shows enormous potential in wastewater treatment and sludge fermentation.

This study develops a novel design scheme based on engineering fluid mechanics for the single-pipe-type sludge drainage mechanism of sedimentation tanks in the wastewater treatment industry. A laboratory-scale clarifier is fabricated for experimental verification. Sludge drainage ratio and suspended solids (SS) of inflow are selected as two factors for laboratory experiments, and SS values are measured to evaluate the performance of the sludge drainage pipe. Experiment data show that the designed single sludge drainage pipe can successfully achieve the supposed task with a coefficient of variation (CV) of SS less than 8.5%. The variation scope of CV from 1.5% to 8.3% suggests that the sludge drainage performance is relatively steady. Nine sets of 3D computational fluid dynamic (CFD) simulations, which is based on the inhomogeneous Eulerian–Eulerian multiphase model, were conducted for a comprehensive exploration and assessment. Results reveal noticeable deviations of the characteristics of the fluid in the outermost orifice of the sludge drainage pipe from the designed value. Although the fluid velocity through each orifice is matched with the designed values, the mass flowrate differs with a maximum of four times the designed value and a standard deviation of 0.4 of hole among the nine simulations. This study also suggests some considerations in the design process and routine operation of the single-pipe-type sludge drainage system.

Despite aerobic granular sludge wastewater treatment plants operating around the world, our understanding of internal granule structure and its relation to treatment efficiency remains limited. This can be attributed in part to the drawbacks of time-consuming, labor-intensive, and invasive microscopy protocols which effectively restrict samples sizes and may introduce artefacts. Time-domain nuclear magnetic resonance (NMR) allows non-invasive measurements which describe internal structural features of opaque, complex materials like biofilms. NMR was used to image aerobic granules collected from five full-scale wastewater treatment plants in the Netherlands and United States, as well as laboratory granules and control beads. T1 and T2 relaxation-weighted images reveal heterogeneous structures that include high- and low-density biofilm regions, water-like voids, and solid-like inclusions. Channels larger than approximately 50 μm and connected to the bulk fluid were not visible. Both cluster and ring-like structures were observed with each granule source having a characteristic structural type. These structures, and their NMR relaxation behavior, were stable over several months of storage. These observations reveal the complex structures within aerobic granules from a range of sources and highlight the need for non-invasive characterization methods like NMR to be applied in the ongoing effort to correlate structure and function.

The petrochemical wastewater includes many toxic organic compounds, which are refractory substances. It is difficult for the wastewater to meet discharge standards after biological treatment, therefore, the further effective treatment of post-biochemical petrochemical wastewater has become an urgent problem to be solved. This study used iron tartaric acid chelate (ITC) catalytic ozonation to treat the petrochemical wastewater. Various key factors were investigated, such as hydraulic retention time (HRT), catalyst dosage, ozone concentration, initial pH values and oxidation efficiency. The kinetics of catalytic ozonation were established. The results indicate that the chemical oxygen demand (COD) removal rate reached a maximum of 58.5%, when the Fe2+ dosage is 0.25 mmol L−1, the initial pH value is neutral, the liquid phase ozone concentration is about 1.95 mg L−1, and HRT is equal to 180 min. In addition, when HRT is equal to 90 min, the B/C ratio of wastewater increases to 0.31, the catalytic ozone reaches maximum oxidation efficiency, and the most economical HRT was 90 min. Finally, the kinetics of ITC catalytic ozonation catalyzed with ITC is consistent with the pseudo-first-order kinetic reaction, and its rate constant is 0.00484 min−1.

Combining microalgae and nitrifiers in a single photobioreactor has attracted attention as an alternative approach for conventional nitrogen removal from wastewater. However, nitrifiers are known to be sensitive to light exposure. This study demonstrated the effectiveness of using fluidized carriers to mitigate light stress in nitrifiers. An outdoor raceway pond containing microalgae and nitrifiers with fluidized carriers was used to treat two-fold diluted anaerobic digestion effluent (785 mg-N L−1 as a form of dissolved total Kjeldahl nitrogen: TKN) over 50 days. The average daily sunlight intensity reached the inhibition level of nitrifiers (423 μmol photons m−2 s−1); however, stable nitrification with a specific ammonium oxidation rate of 55 mg-N g-total suspended solid−1 day−1 was observed. TKN was mostly removed via nitrifier metabolism (ammonium oxidation and uptake: 40.1%) and partially via microalgae uptake (5.7%). Different microalgae-based processes including that of this study were compared in terms of tolerances to a high dissolved TKN concentration and strong light. Our system showed a relatively higher resistance to not only light exposure but also TKN because the nitrification process decreased the free ammonia level to less than 0.25 mg L−1, which allowed microalgae to grow despite the high ammonium concentration.

New industrial and urban developments in water-scarce regions are often inhibited by their high demand for water from natural resources. In addition, there often is a lack of water for purposes that contribute to an improved quality of life, such as urban green spaces. Therefore, the integrated industrial-urban water-reuse concept presents a strategy by linking and reusing treated industrial and municipal wastewater flows to increase urban water-reuse potentials. The concept of combining different reuse water flows, from wastewater treatment plants from industrial parks, aims at significantly increasing the water-saving potentials compared to a separate consideration of the industrial wastewater flows.

Rapid population growth, industrial development and stringent demand for treatment of wastewater require developing and emerging economies to upgrade existing wastewater treatment plants (WWTPs) or planning new WWTPs. In the context of unavailability or unaffordability of land and resources for infrastructure expansion, low cost, small footprint, less energy consumption and product reuse are some of the major factors to be considered when either upgrading or designing new WWTPs in developing and emerging economies. Although the transition from activated sludge to biofilm processes has partly solved these challenges, there are innovations that can make the processes even more compact and more efficient. Newly developed CFIC (continuous flow intermittent cleaning) process is the next generation moving bed biological wastewater treatment system and is an example for addressing these issues. The CFIC pilot studies showed promising performance for biological chemical oxygen demand and nitrogen removal as well as particle separation facilitating wastewater reuse.

Changes in dilution of wastewater to a treatment plant due to infiltration or surface runoff can have a great impact on treatment process performance. This paper presents a model-based approach in which realistic influent scenarios are generated and used as inputs to a dynamic plant-wide process model of the wastewater treatment plant. The simulated operation is subsequently evaluated using life-cycle assessment (LCA) to quantify the environmental impacts of the future influent scenarios. The results show that increased infiltration led to higher environmental impact per kg nitrogen removed. The increase in surface runoff had a minor impact.

The lignite upgrading wastewater (LUW) produced in the drying and upgrading process of lignite cannot be discharged directly. Conventional wastewater treatment methods are usually costly and unable to achieve efficient utilization of water resources which are rich in activity components. In this study, the water quality analysis showed that LUW belonged to seriously polluted waters with low pH and very high total nitrogen content. Fifty-five compounds, mainly phenols and organic acids, were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The study confirmed that the LUW, after being diluted to an appropriate concentration, could significantly promote the growth of wheat seedlings. The phenols and organic acids were the activity material basis of LUW, which promoted seed germination possibly through playing a role similar to plant hormones and simultaneously enhancing the utilization of nutrient elements. LUW had the natural advantages of directly developing high-end liquid fertilizers in terms of its physical form, chemical composition, biological activity, safety and economy. This study confirmed the feasibility of applying LUW to agricultural field as liquid fertilizer only through simple dilution without other treatments. Applying LUW as liquid fertilizer can not only supply a fertilizer product with low production cost and outstanding efficacy, but also provide an efficient and green way for the treatment of upgrading wastewater, which utilize the LUW as natural resources instead of purifying and discharging.

Oxic-settling-anaerobic (OSA) process is effective in minimizing sludge production, by inserting an anaerobic side-stream reactor (ASSR) in the recycling bypass. Interchange ratio (IR), the quantity ratio of sludge entering the ASSR to the sludge in the main stream reactors, is one of the most important parameters for OSA process. In the present study, a laboratory-scale anaerobic/anoxic/oxic (A2/O) process combined with an ASSR (A2/O-ASSR) was operated for 366 days in parallel with a conventional A2/O process to investigate the effects of IR on sludge reduction. IR was assigned values of 5%, 8%, 10%, and 15%, and the A2/O-ASSR process achieved 14.0%, 16.0%, 24.1%, and 13.7% of sludge reduction, respectively. At the optimum IR of 10%, high through-put sequencing analysis showed that the microbes responsible for pollutant removal and ubiquitous in wastewater treatment remained predominant in the two systems, and slow-growing microbes related to hydrolysis, nitrogen and phosphorus removal increased in the A2/O-ASSR process, which probably played a key role in sludge reduction. 40.6–58.6% of sludge reduction was caused by sludge decay in the ASSR. The tiny amount of extracellular polymeric substance released in the A2/O-ASSR process was subthreshold to cause remarkable sludge reduction.

In this study, the effect of Spathiphyllum blandum on the removal of ibuprofen (IB) and conventional pollutants such as chemical oxygen demand (COD), total nitrogen (TN), ammonium (NH4+-N), total phosphorus (TP), and total suspended solids (TSS) is reported; this, through its use as an emergent vegetation in fully saturated (FS) constructed wetlands (CWs) at mesocosm level treating polluted river water. With the exception of TP and COD, it was found that for TN (12%), NH4+-N (11%), TSS (19%), and IB (23%), the removals in systems with vegetation were superior to systems without vegetation (p < 0.05). These findings demonstrate the importance of the species S. blandum, in particular, for the removal of ibuprofen, which is an anti-inflammatory drug commonly found in effluents of wastewater treatment plants. Thus, the results obtained provide information that can be used for the design of future efficient large-scale systems using a new ornamental species, mainly under tropical climatic conditions. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

Foam potential and viscometer ramp tests (VRTs) were conducted for three municipal wastewater treatment plants to determine if these methods can relate to mechanisms of foaming to physical and biological constituents in sludge. At all plants, digester volatile solids (VS) concentration correlated (R2 > 0.41) with increases in plastic viscosity, a VRT parameter corresponding to foaming risk. Plastic viscosity also correlated with foam-causing bacteria Gordonia (R2 = 0.38). Foam potential test values increased with Microthrix parvicella (R2> 0.28). For one plant, suspected foam-causing bacteria Mycobacterium negatively correlated with parameters representing foam risk. Microscopic filament counting correlated (R2 = 0.97) with quantitative polymerase chain reaction (qPCR) for Gordonia, suggesting that the more accessible counting method can reliably quantify foam-causing bacteria. Foam potential tests and VRTs resulted in plant-specific correlations with foam-related constituents. Therefore, these tests may provide useful evidence when investigating causes of digester foam events.

The objective of this study was to evaluate the influence of a new species of plant (Spathiphyllum blandum) in the elimination of chemical oxygen demand (COD), nitrogen, phosphorus and fecal coliforms (FCs) in mesocosms of wetlands with polyethylene terephthalate (PET) and tezontle substrates under a tropical climate. The experiments were developed at the mesocosm level in 20 experimental units; 10 were planted with Spathiphyllum blandum, five in PET substrates and five in tezontle, and 10 more were used as controls without vegetation, of which five contained tezontle and five contained PET. The systems were fed with contaminated water from the river Sordo, with a hydraulic retention time of 3 days for 12 months; samples were taken in the influent and effluents of the mesocosms every 2 weeks, with the purpose of evaluating the removal of contaminants. The results showed that presence of this species tended to improve or significantly improved the removal of COD, NH4-N, PO4-P, and FCs by 7%, 16%, 29% and 12%, respectively. It was also possible to confirm that the presence of this species reduced the rate of denitrification. These results confirm that in developing countries it is feasible to find new wetland species to be used for wastewater phytoremediation.

An unconventional cascade control system, for the regulation of air supply in activated sludge wastewater treatment plants (WWTPs), was tested. The dissolved oxygen (DO) set point in the aeration tank was dynamically calculated based on effluent ammonia concentration, following a fuzzy logic based approach. First, simulations were conducted, according to the BSM2 protocol, for a general comparison with more conventional control strategies. It turned out that the effluent quality could be improved by 7–8%, based on the EQI parameter. Moreover, the aeration energy requirement could be reduced up to 13%. Subsequently, the system was installed in a full-scale WWTP. While stably complying with the ammonia effluent standard (10 mg/L), excess air supply was prevented, and a reduction of the specific power consumption (kWh/kgCODremoved) of 40–50% was recorded with respect to the previously installed PID controller (fixed DO set point).

Wastewater treatment plants are not specially designed to remove pharmaceutically active compounds (PhACs), since these substances are toxic and bio-refractory. This paper aims to investigate and optimize the performance of the Trisep TS80 nanofiltration (NF) membrane for the removal of a mixture of two of the most detected PhACs in municipal wastewaters worldwide, sulfamethoxazole and diclofenac. Several NF tests were carried out to study the rejections of these contaminants both spiked in demineralized water, filtrated water taken from Mondego River and secondary effluent coming from a municipal wastewater treatment plant. Among the several studied operating variables, pH was the one that most affected the contaminant rejection and membrane permeability. In the case of synthetic effluent, an applied pressure of 10 bar and pH 7 were determined as the best operating conditions, which allowed almost total chemical oxygen demand retention and a global contaminant rejection of 96.3% to be achieved. The application of different water matrices (river water and secondary municipal effluent) had no relevant impact on process efficiency. Vibrio fischeri luminescence inhibition tests revealed that treatment by nanofiltration reduced acute toxicity of all studied effluents.

Struvite was observed within the microalgae biofilm matrix of an outdoor, pilot-scale rotating algal biofilm reactor (RABR) designed to remove nitrogen and phosphorus from municipal anaerobic digester filtrate. The bottom layer of cells (2.5-month growth) and two top layers of cells (1-week and 2.5-month growth) were evaluated on east- and west-facing sides of the RABR. Sun orientation and shading effects of upper biofilm layers impacted the species composition and microalgae content of the bottom biofilm layers. Struvite formed within the microalgae biofilm matrix, and a higher struvite content appeared to be correlated with a higher microalgae content. The highest struvite content (expressed as %wt. of total solids) was observed in the east- and west-facing bottom layers of growth and west-facing 1-week growth (5.0%, 4.3%, and 4.1%, respectively). The lowest struvite content was observed in east- and west-facing 2.5-month growth and east-facing 1-week growth (1.1%, 1.5%, and 1.1%, respectively). Despite RABR influent component ion molar ratios with potential for various magnesium and calcium precipitates, microalgae biofilm provided pH and nucleation sites favorable to struvite precipitation. This evaluation is the first in the refereed literature the authors are aware of that reports on the association of struvite formation in the presence of a microalgae biofilm.

Optimal operation of membrane bioreactor (MBR) plants is crucial to save operational costs while satisfying legal effluent discharge requirements. The aeration process of MBR plants tends to use excessive energy for supplying air to micro-organisms. In the present study, a novel optimal aeration system is proposed for dynamic and robust optimization. Accordingly, a deep reinforcement learning (DRL)-based optimal operating system is proposed, so as to meet stringent discharge qualities while maximizing the system's energy efficiency. Additionally, it is compared with the manual system and conventional reinforcement learning (RL)-based systems. A deep Q-network (DQN) algorithm automatically learns how to operate the plant efficiently by finding an optimal trajectory to reduce the aeration energy without degrading the treated water quality. A full-scale MBR plant with the DQN-based autonomous aeration system can decrease the MBR's aeration energy consumption by 34% compared to other aeration systems while maintaining the treatment efficiency within effluent discharge limits.

Many developing countries, mostly situated in the tropical region, have incorporated a biological nitrogen removal process into their wastewater treatment plants (WWTPs). Existing wastewater characteristic data suggested that the soluble chemical oxygen demand (COD) in tropical wastewater is not sufficient for denitrification. Warm wastewater temperature (30 °C) in the tropical region may accelerate the hydrolysis of particulate settleable solids (PSS) to provide slowly-biodegradable COD (sbCOD) for denitrification. This study aimed to characterize the different fractions of COD in several sources of low COD-to-nitrogen (COD/N) tropical wastewater. We characterized the wastewater samples from six WWTPs in Malaysia for 22 months. We determined the fractions of COD in the wastewater by nitrate uptake rate experiments. The PSS hydrolysis kinetic coefficients were determined at tropical temperature using an oxygen uptake rate experiment. The wastewater samples were low in readily-biodegradable COD (rbCOD), which made up 3–40% of total COD (TCOD). Most of the biodegradable organics were in the form of sbCOD (15–60% of TCOD), which was sufficient for complete denitrification. The PSS hydrolysis rate was two times higher than that at 20 °C. The high PSS hydrolysis rate may provide sufficient sbCOD to achieve effective biological nitrogen removal at WWTPs in the tropical region.

Food industry wastewater (FIWW) streams with high organic content are among the most suitable and inexpensive candidates for polyhydroxyalkanoate (PHA) biopolymer production. Due to its high organic acid content, pickle industry wastewater (PIWW), can be considered as one of the prospective alternatives to petroleum-based polymers for PHA production. In this context, this study aimed to investigate the production of PHA with enriched microbial culture using PIWW. Two laboratory scale sequencing batch reactors (SBRs) were operated under aerobic dynamic feeding conditions at a sludge retention time of 8 days, with a total cycle duration of 24 hours. SBRs were fed with peptone mixture and PIWW. In-cycle analysis and batch respirometric tests were performed to evaluate PHA storage together with biodegradation kinetics. In-cycle analysis showed that maximum PHA content was 1,820 mgCOD/L, corresponding to 44% in the biomass (ratio of chemical oxygen demand (COD) to volatile suspended solids) for PIWW. Experimental results were also confirmed with activated sludge model simulations. As for the PHA composition, hydroxybutyrate was the major fraction. Model simulations proposed a unique conversion–degradation–storage pathway for the organic acid mixture. This paper presents a novel insight for better understanding of PHA biopolymer production using high saline FIWW.

The aim of this work was to develop a method that allows the recovery of nutrients from aquaculture sludge, not only to alleviate the disposal problem, but also to address the future scarcity of non-renewable fertilizers. This method includes two steps: Nutrient mobilization using aerobic digestion followed by solids precipitation using chitosan as the flocculant. The aerobic digestion experiments were conducted in aerated batch reactors, while a jar test apparatus was used to assess the capacity of chitosan to remove total suspended solids (TSS) and turbidity. During aerobic digestion, the concentration of soluble N (sum of NH4-N, NO2-N, NO3-N) increased from 181 mg/L at the start to 890 mg/L after three weeks, and to 903 mg/L after four weeks and solids removal by chitosan flocculation. The corresponding concentrations for soluble P were 8.2 mg/L at start, 110 mg/L after three weeks of aerobic digestion, and 160 mg/L after four weeks of aerobic digestion and chitosan flocculation. Other macronutrients (K, Ca, Mg, S) and micronutrients (Fe, Mn, Zn, B, Cu, Mo) were mobilized to concentrations close to or higher than levels recommended for hydroponic growth of vegetables. Chitosan flocculation and precipitation using a dose of 15 mg/L resulted in a reduction of the turbidity by 96% from 156 to 6.5 FNU. After chitosan precipitation, 80% of the sludge could be reclaimed as a nutrient-rich clear phase, low in TSS and turbidity.

In this study, the influence of total suspended solids (TSS) and particle size as well as effluent temperature on peracetic acid (PAA) decomposition kinetics in municipal wastewater was investigated. PAA decomposition was best described following second order kinetics in primary effluent (PE) and first order kinetics in secondary effluent (SE) samples. For synthetic samples prepared by varying TSS levels, PAA demand increased on average by about 0.042 mg/L in PE and 0.034 mg/L in SE for every 10 mg/L increase in TSS. Similarly, the PAA decay rate constant in these samples increased at a rate of 0.0014 L/mg.min and 0.00039 min−1, respectively, per 10 mg/L TSS. To examine the effect of particle size, synthetic samples with narrow size fractions (20–45, 45–75, and 75–90 μm) were prepared. It was found that samples with smaller particle size fractions had a greater PAA demand and decay rate constant. Effluent temperature also enhanced the PAA decomposition rate with the calculated activation energies for PE and SE samples being 29,980 J/mol and 34,860 J/mol, respectively.

Anaerobic co-digestion of sewage sludge with organic wastes has recently gained attention in small facilities. For small facilities, high solids sludge is suitable for transportation to a centralized co-digester, and direct utilization of the digested sludge as liquid fertilizer is recommended. Effects of high solid and hyperthermophilic pretreatment (80 °C, 24 hr) on anaerobic digestion at low temperatures and utilization as fertilizer are investigated by anaerobic/aerobic digestion and paddy soil incubation experiments. The volatile solids (VS)/total solids (TS) ratio decreases to 0.57(-), and the VS removal rate is approximately 0.7 (-) after long-term aerobic digestion. This is possibly the limitation of biodegradation, even with pretreatment, within engineering time. Substrate TS of 16% (not diluted), 10% and 5% are compared. The effect of substrate TS on biogas production performance (0.2–0.3 NL/gVS-added) is not statistically observed. Laboratory-scale paddy soil incubation experiments are performed fed with anaerobically digested pretreated or not pretreated dewatered sludge as liquid fertilizer. Pretreatment promotes nitrogen mineralization before use as fertilizer, which is helpful to prevent an outflow of surplus ammonia to the environment. The effect of soil type on microbial communities is more significant than that of anaerobically digested sludge conditions.

The treatment of wastewater for reuse is a potential solution to meet ever increasing urban, industrial, agricultural, and environmental demands across the world, where clean water availability is scarce. There are several traditional wastewater treatment processes that offer varying degrees of effectiveness in addition to presenting environmental, economic, and social disadvantages. Development of promising and inexpensive technologies to provide the reusable water in needful amounts using wastewaters as a cheap source of key nutrients and organic matter is required. Wastewater treatment by biological methods is becoming more important in the light of recovering value-added plant nutrients, heavy metals, biosolids, and bioenergy resources. Different types of solid contaminants in effluents can be removed simultaneously by pure cultures or mixed microbial consortia. Based on the structural organization of microbial biomass, biological treatment systems are classified into two types: dispersed growth system and attached growth system. Biological treatment methods associated with fixed-film growth have been recognized as highly effective and more energy efficient than suspended growth systems. This review discusses the recent breakthroughs in advanced biological wastewater treatment using both the systems, and also focuses on key energetic resources recovery driven by biological technologies.

Large volumes of process water and steam are required for extraction and refining of edible seed oils. Water usage in most industries has decreased over the years as increasing emphasis is being placed on water re-use in modern facilities. However, given the size of the edible seed oil industry globally, there is a lack of current quantitative data about water use and wastewater generation. As the world moves towards a circular economy and water becomes more scarce, it is imperative that the industry players provide meaningful input/output data in order to benchmark and identify areas for waste valorization. This review provides data currently available in the public domain on the specific wastewater intake and wastewater generation by the edible seed oil industry, highlighting the need for further data collection. In addition, wastewater quality and current and future wastewater treatment technologies are discussed, as well as the potential for valorization of solid waste and effluent from the industry, and potential avenues for future research.

Postaeration, where digested sludge is introduced into aerobic conditions, is a technology that could improve the quality of sludge and sludge liquor in many ways. Although it is a fairly simple process, only few data about the effect of postaeration have been published. In this study, batch experiments have been performed first, indicating that postaeration affects the total ammonia nitrogen (TAN) and sludge dewaterability. In the removal of TAN, both stripping and biological oxidation can play an important role depending on specific condition. Then the postaeration was investigated in a semicontinuous batch reactor. In addition, the effect of postaeration on the concentration of selected micropollutants such as pharmaceuticals, EOX and AOX was studied. The hydraulic retention time (HRT) of 8, 6, 4 and 2 days and different aeration intensities were tested. The TAN removal efficiency achieved was about 40–60%, sludge dewaterability expressed by sludge cake total solids (TS) concentration after dewatering improved relatively by 5–30%. In addition, TS degradation is also taking place and therefore the reduction of the amount of final sludge to be disposed could be even higher. The biggest changes in observed parameters were recorded at the longest HRT.

The present research was conducted to assess the feasibility of biological treatment of a typical wastewater (WW) stream in Multan, Pakistan, using daily trends of WW characteristics and to design a wastewater treatment (WWT) system for that stream. The pH (5.8–6.2), temperature (24–30 °C), biological oxygen demand (BOD5: 128–265 mg/L), ultimate BOD (BODu: 227–438 mg/L), BOD/total Kjeldahl nitrogen (BOD5/TKN:5.9–11.2), BODu/BOD5 (1.6–2.0), carbonaceous BODu/nitrogenous BODu (CBODu/NBODu:1.6–2.8) of the WW was found to support the biological WWT. The inclusion of NBOD also indicated the need for nitrification-denitrification. The linear regression analysis of volatile suspended solids (VSS) with total suspended solids (TSS) indicated the high content of organic solids, which also made the WW suitable for biological treatment. The BOD/COD (chemical oxygen demand)

A simultaneous nitrification and denitrification (SND) bioaugmention system with Pseudomonas sp. HJ3 inoculated was established to explore the potential of simultaneous phenol and nitrogen removal in coal gasification wastewater (CGW). When the concentration of influent chemical oxygen demand (COD) and total phenols (TPh) was 1,765.94 ± 27.43 mg/L and 289.55 ± 10.32 mg/L, the average removal efficiency of COD and TPh at the stable operating stage reached 64.07% ± 0.76% and 74.91% ± 0.33%, respectively. Meanwhile, the average removal efficiency of NH4+-N and total nitrogen (TN) reached 67.96% ± 0.17% and 57.95% ± 0.12%, respectively. The maximum SND efficiency reached 83.51%. Furthermore, SND bioaugmentation performed with good nitrification tolerance of phenol shock load and significantly reduced toxic inhibition of organisms. Additionally, the microbial community analysis indicated that Pseudomonas sp. HJ3 was the predominant bacterium in the SND bioaugmentation system. Moreover, the indigenous nitrogen removal bacteria such as Thauera, Acidovorax and Stenotrophomonas were enriched, which further enhanced the nitrogen removal in the SND bioaugmentation system. The results demonstrated the promising application of SND bioaugmentation for enhancing simultaneous phenol and nitrogen removal in CGW treatment.

Many rural areas of Latin America and the Caribbean (LAC) region are economically depressed. Rural sewage treatment in most areas of LAC is deficient or non-existent. Consequently, the possibility of generating economic revenue from treated sewage is an attractive option for deprived areas of developing countries. Given its peculiar characteristics, rural sewage may be coupled with biological systems such as algae for nutrient cycling. Acceptable algae growth and nutrient elimination were obtained from rural sewage whose treatment may have fallen short of current disposal standards. In this study, aerobic systems working on an 8-month cycle at three different volumetric loading rates (Bv) were assessed in relation to the lifetime growth of three algae strains native to Ecuador. Results indicate Chlorella sp. M2 as the optimal algal strain, with the highest growth rate at Bv of 1 g COD L−1 d−1 and a removal of organic-N (30%), PO43–-P (87%) and NH4+-N (95%). Concomitantly, the kinetic constants of the sewage resulted in a low biomass yield coefficient, making the proposed system highly suitable for developing countries. Finally, the proposed partial recovery stream method, combining nutrient recovery with economic resource generation, appears to contain great potential.

Characteristics of Chlorella sorokiniana treating wastewater with consideration of HRT (6 d, 16 h, 8 h), hydraulic conditions, light or dark culture were evaluated and compared with activated sludge. Results showed that optimal HRT was 8 h; if longer, effluent chemical oxygen demand (COD) and NH4+-N in the dark began to rebound. Mixing was beneficial to COD removal of algae, while aeration was suitable for nutrient removal. Growth of C. sorokiniana in the light was mixotrophic growth and 1.3–1.7 times more than that of dark heterotrophic growth. The maximum specific growth rate (µmax), productivity, and biomass yields on COD (YCOD), N (YNH4), P (YP) of algae were higher in the light than that in the dark. COD assimilation capacity of algae was similar to activated sludge but with different dynamics. N and P assimilation capacity of algae was 1.4, 1.2–2.5 times more than activated sludge; N and P removal efficiency of algae was 5%–10%, 10%–55% respectively higher than activated sludge. This study confirmed the advantage of algae over activated sludge and reveal why algae could assist the activated sludge process.

La utilizacion del sistema frances de humedales verticales para el tratamiento de aguas residuales crudas sigue aumentando, pero todavia hay informacion consolidada limitada sobre su uso a largo plazo en paises tropicales. En estas condiciones, hay indicios de que los requisitos de superficie pueden disminuir, mientras se mantiene un rendimiento satisfactorio. Sin embargo, las variaciones en el modo operativo y el papel de la capa de deposito organico superficial en condiciones climaticas calidas no se han investigado completamente. El objetivo de este trabajo fue evaluar el rendimiento de un sistema compuesto solo por la primera etapa del sistema frances, con una reduccion adicional de 1/3 del area (utilizacion de solo dos unidades en paralelo, en lugar de tres) en terminos de eliminacion de materia organica y conversion de nitrogeno, con una unidad con una capa de deposito acumulada durante 9 anos de operacion, y la otra unidad sin capa de lodo, en condiciones tropicales brasilenas. El sistema se diseno originalmente de acuerdo con las recomendaciones de Cemagref / Irstea para la primera etapa del sistema frances para el tratamiento de las aguas residuales sin tratar generadas por una poblacion equivalente de 100 habitantes. Sin embargo, mas tarde se cambio y funciono con solo dos unidades, utilizando solo 0.6 m2 · pe − 1. Los periodos de alimentacion y descanso fueron de 7 dias cada uno. Para evaluar la influencia de la capa de lodo, se elimino el lodo superior de una de las unidades y se comparo el rendimiento de ambas unidades mediante la prueba de Mann-Whitney. La base de datos comprende los valores de rendimiento del humedal en terminos de oxigeno disuelto (OD), potencial redox (Eh), demanda quimica de oxigeno (DQO), demanda bioquimica de oxigeno (DBO), solidos suspendidos totales (SST), nitrogeno total Kjeldahl (NTK), NH4 + -N y NO3 + -N, cubriendo un periodo de monitoreo de 15 meses. Las concentraciones de OD del efluente fueron significativamente mas bajas en la unidad con lodo superior, pero aun lo suficientemente altas en ambas unidades. Aunque hubo algunas variaciones entre ambas unidades, las concentraciones de efluentes de los principales contaminantes no fueron significativamente diferentes en las unidades con y sin lodo, y las eficiencias de eliminacion basadas en los valores medios se consideraron buenas, dada la reducida area del sistema: DBO (80% y 79%), SST (85% y 82%), NTK (60% y 63%) para las unidades con y sin lodo, respectivamente. En condiciones climaticas brasilenas, con un area reducida y empleando ciclos de alimentacion mas largos (7 dias), la tasa de acumulacion de lodo (menos de 1 cm · ano − 1) fue menor en comparacion con los valores medios franceses.

With the rapid development of urbanization, the amount of urban sewage treatment is increasing. Waste activated sludge (WAS) is a by-product of sewage treatment, and its output is increasing year by year. How to properly handle WAS is related to the sustainable development of the sewage treatment industry. The production of ceramsite from WAS is an effective way to realize the utilization of sludge. This paper comprehensively describes the use of WAS as raw material, adding clay, cement, glass powder, shale, coal gangue, river sediment, pulverized fly ash and other auxiliary materials (AM) to produce sintered sewage sludge ceramsite and non-sintered sludge ceramsite. This paper analyzes the advantages and disadvantages of the process of making ceramsite from WAS. The research points out the development prospect of ceramsite from WAS.

This work evaluates the reduction of scum accumulation on the top surface of upflow anaerobic sludge blanket (UASB) reactors by the addition of hydrolytic enzymes in their feed. For over 1 year, two UASB reactors of 1.4 L were maintained at 30 °C and continuously fed with synthetic domestic wastewater (containing 150 mg/L of soybean oil) under a hydraulic retention time of 10 h. The Control reactor was only fed with synthetic wastewater. Beginning at the 226th day of operation, low-cost hydrolytic enzymes (obtained by solid-state fermentation of Aspergillus terreus, a fungus isolated from a primary sewage sludge) were added into the feed of the other reactor (Test) for a lipase activity of 24 U/L, considerably reducing the formation of scum. In the Test reactor, the scum showed oil and grease (O&G) concentration between 0.8 and 1.3 g/L and an accumulation rate of 20 to 27 mg O&G/d. In the Control reactor, the scum had values twice as high (1.5–2.5 g/L and 34–51 mg O&G/d, respectively) and there were more operational problems. During the entire period of operation, both reactors presented high chemical oxygen demand removal (>80%), with no loss of effluent quality due to the addition of the enzymes.

In wastewater treatment plants the antagonistic activities of actinomycetes could be contributing significantly in microbe-removing mechanisms, which are a combination of different factors. For this purpose, out of 58 actinomycetes isolates from a wastewater treatment plant in Al-Fayoum Governorate, Egypt, only 36 different morphological isolates were selected for further studies. Although 35 isolates (97.23%) were active against one or more of tested bacteria, WD5 isolate had broad-spectrum antagonistic activity against both Gram-negative and Gram-positive tested bacteria. WD5 ethyl acetate extract recorded the highest antibacterial activity against Staphylococcus aureus MTCC 96 (23 mm) and the lowest antibacterial activity against Pseudomonas aeruginosa MTCC 2453 (11 mm). Gas chromatography-mass spectrometry analysis of extract using available NIST (National Institute of Standards and Technology) library data identified seven bioactive compounds: 2-methylbutyl acetate, 3′,5′-dinitrobenzoic acid, 1-octadecene, tetradecane, dodecane, docosane, and methylamine,N,N-bis(N.-decyl). Many earlier studies mentioned the antibacterial activity of all above seven compounds. The 16S rRNA sequence of WD5 was recorded in GenBank under the accession number MK491056 and confirmed by comparing it with the known 16S rRNA sequences in GenBank as Streptomyces sp. These results indicated antagonistic activity of actinomycetes in the removal of wastewater-associated bacteria.

Urban hydrology was created in order to improve methods of managing the runoff of precipitation in towns and protect them from flooding while also protecting public health and environment. The essence of a future solution consists in finding an acceptable compromise of an alternative solution for draining rainwater from a territory. The content of this work is a study focused on resolving the percolation of water from surface runoff and the confrontation between a field test, laboratory analysis, and numerical analysis. By confronting and subsequently proposing conditions for percolation, documents will be created for making urban drainage better and more efficient. The reason for the origin of the subject work follows from the insufficient information on infiltration systems in Slovak technical standards and, likewise, the lack of support for the percolation of water from surface runoff. This work points out the approaches, principles, and fundamentals of a proposal for percolation. The aim of the work is distribution of scientific knowledge in the field of research and solutions for the percolation of water from surface runoff, with emphasis placed on the retention capacity of the selected territory and the intensity of precipitation. A geological study (orientational, detailed or supplementary) must always be conducted with any decision on rainwater percolation in a certain locality. Its range is dependent on the difficulty and type of construction. The preliminary study of areal condition should be focused on detailed engineering-geological and hydrological information. After this work, it is concluded that the percolation of rainwater in urban areas with suitable hydrogeological condition is an effective rainwater management technology as well as protection to congestion of sewer systems.

This study mainly focuses on the process of electrocoagulation (EC) for the wastewater treatment from biodiesel production using waste cooking oil. The effects of current density, initial pH and electrolysis time on the EC process using aluminum (Al) and iron (Fe) electrodes were investigated for removal of chemical oxygen demand (COD). The COD removal efficiencies were found to be 62.7% and 63.4% at optimum conditions for Al (current density: 43 mA/cm2, pH: 5, time: 21 min) and Fe (current density: 47 mA/cm2, pH: 7.7, time: 30 min) electrodes, respectively. At these optimum conditions, the removal efficiencies of oil & grease, total phosphorus (TP), orthophosphate (PO4-P) and total suspended solids (TSS) were determined respectively to be above 89.9%, 98.9%, 99.5%, 86.7% for Al electrodes and 90.8%, 98.5%, 97.6%, 89.6% for Fe electrodes. Total operating costs were also found to be 6.43 €/m3 and 7.01 €/m3 for Al and Fe electrodes, respectively. The results indicate that the EC process using both types of electrodes seems to ensure an efficient treatment of biodiesel wastewater in terms of oil & grease and TP.

Nowadays, low greenhouse gas (GHG) emission is expected at wastewater treatment plants (WWTPs). However, emission quantification and evaluation still faces difficulties related to data availability and uncertainty. The objective of this study was to perform carbon footprint (CF) analysis for two municipal WWTPs located in northern Poland. Slupsk WWTP is a large biological nutrient removal (BNR) facility (250,000 PE) which benefits from on-site electricity production from biogas. The other studied plant is a medium-size BNR facility in Starogard (60,000 PE). In this WWTP, all the required electricity was provided from the grid. Both wastewater systems were composed of activated sludge, with differences in the nutrient removal efficiency and sludge treatment line. The CF calculations were based on empirical models considering various categories of input parameters, afterwards summing up the emissions expressed in CO2 equivalents (CO2e). After sensitivity analysis, significant contributors to GHG emissions were identified. The total specific CF of the Slupsk and the Starogard WWTP was 17.3 and 38.8 CO2e per population equivalent (PE), respectively. In both cases, sludge management, electricity consumption and direct emissions from wastewater treatment were found to significantly influence the CF. A substantial share of the total CF originated from indirect emissions, primarily caused by the energy consumption. This negative impact can be partially overcome by increasing the share of renewable energy sources. Reduction of over 30% in the total CF could be achieved while applying energy recovery from biogas by combined heat and power plants. Farmland and farmland after composting were found to be the most appropriate strategies for sludge management. They could create a CF credit (8% of the total CF) as a result of substituting a synthetic fertilizer. Reliable full-scale measurements of N2O emissions from wastewater treatment are recommended due to high uncertainty in CF estimation based on fixed emission factors (EFs). While applying the lowest and the highest N2O EFs reported in the literature, the total CF would change even by 2–3 times.

A magnetic cotton stalk biochar (MCSBC) was synthesized through chemical co-precipitation, based on cotton stalk biochar (CSBC). The MCSBC and CSBC were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and vibrating sample magnetometry. The characterization analyses showed that the magnetization process endowed the CSBC with excellent magnetic properties with a superparamagnetic magnetization of 27.59 emu/g. Batch adsorption experiment results indicated that the Cr(VI) maximum adsorption capacity of MCSBC was 20.05 mg/g, which was higher than that of CSBC (18.77 mg/g). The adsorption kinetic data were well fitted by the pseudo-second-order model and the adsorption isotherms were well represented by the Sips isotherm model. The thermodynamic studies indicated that the adsorption process was spontaneous and endothermic, and the entropy increased. The potential adsorption mechanism was the electrostatic adsorption of anionic Cr(VI) to the positively charged MCSBC surface, the reduction of Cr(VI) into Cr(III) and the complexation of Cr(III) by oxygen-containing functional groups of MCSBC. The regeneration studies showed that MCSBC kept 80% of its initial Cr(VI) adsorption capacity in the cycle. All the findings suggest that this novel magnetic biochar could be used in the field of Cr(VI)-containing wastewater treatment.

This study examined the dynamics of iron (Fe) and phosphorus (P) transformations from the surface sludge accumulated in tertiary horizontal flow (HF) treatment wetlands (TW) chemically dosed for P removal. Site surveys showed P was stored in HF TW with and without artificial aeration on average, with instances of P release in the non-aerated site. Controlled experiments revealed storing TW surface sludge for over 24 hours resulted in limited oxygen and nitrate concentrations, resulting in both P and Fe release. The rate of P release increased with increasing water-sludge P concentration gradients, and the reaction could take as little as 10 minutes. Convection had no impact on P transformation rates. The findings suggest mitigation strategies could include the manipulation of the biogeochemical environment by managing oxygen and nitrate concentrations within the wetlands. A better understanding of links between Fe, P, and nitrate is needed to test proactive mitigation strategies for small wastewater treatment plants.

The present study assessed the carbohydrate and sugar production from Chlorella spp. biomass harvested from a field scale reactor simulating phycoremediation of swine wastewater. The microalgae biomass was mainly composed by (%): carbohydrates (41 ± 0.4), proteins (50 ± 0.4), and lipids (1.3 ± 0.5). The residual sugar present in the biomass was extracted via acid hydrolysis. Among different concentrations of sulfuric acid tested (i.e., 47, 94, 188, 281 and 563 mM), significantly higher sugar content was obtained with 188 mM (0.496 g-sugar g−1 microalgae-DW). The concentration of sugar present in the microalgae did not differ significantly between the biomasses harvested by either centrifugation or coagulation-flocculation. Two commercially available strains of yeast (i.e., Saccharomyces cerevisiae and S. cerevisiae chardonnay) were tested for their capability to ferment sugar from lyophilized microalgae biomass. S. cerevisiae chardonnay showed a significantly faster consumption of sugar during the exponential growth phase. Both strains of yeast were capable of consuming most of the sugar added ≅ 8 g L−1 within 24 h. Overall, the results suggest that carbohydrate-rich microalgae biomass obtained from the phycoremediation of swine wastewaters can play an important role in green design for industries seeking alternative sources of feedstock rich in sugar.

Addition of food waste (FW) as a co-substrate in anaerobic digesters of wastewater treatment plants is a desirable strategy towards achievement of the potential of wastewater treatment plants to become energy-neutral, diverting at the same time organic waste from landfills. Because substrate type is a driver of variations in phylogenetic structure of digester microbiomes, it is critical to understand how microbial communities respond to changes in substrate composition and concentration. In this work, high throughput sequencing was used to monitor the dynamics of microbiome changes in four parallel lab-scale anaerobic digesters treating sewage sludge during acclimation to an increasing amount of food waste. A co-occurrence network was constructed using data from 49 metagenomes sampled over the 161 days of the digesters´ operation. More than half of the nodes in the network were clustered in two major modules, i.e. groups of highly interconnected taxa that had much fewer connections with taxa outside the group. The dynamics of co-occurrence networks evidenced shifts that occurred within microbial communities due to the addition of food waste in the co-digestion process. A diverse and reproducible group of hydrolytic and fermentative bacteria, syntrophic bacteria and methanogenic archaea appeared to grow in a concerted fashion to allow stable performance of anaerobic co-digestion at high FW. Fil: Orellana, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina Fil: Davies Sala, Carol Giselle. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina Fil: Guerrero, Leandro Demián. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina Fil: Vardé, Ignacio. Investigación, Desarrollo e Innovación. Benito Roggio Ambiental; Argentina Fil: Altina, Melisa Guadalupe. Investigación, Desarrollo e Innovación. Benito Roggio Ambiental; Argentina Fil: Lorenzo, María Cielo. Investigación, Desarrollo e Innovación. Benito Roggio Ambiental; Argentina Fil: Figuerola, Eva Lucia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Pontiggia, Rodrigo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Investigación, Desarrollo e Innovación. Benito Roggio Ambiental; Argentina Fil: Erijman, Leonardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina