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The presence of poly- and perfluoroalkyl substances (PFAS) has caused serious problems for drinking water supplies especially at intake locations close to PFAS manufacturing facilities, wastewater treatment plants (WWTPs), and sites where PFAS-containing firefighting foam was regularly used. Although monitoring is increasing, knowledge on PFAS occurrences particularly in municipal and industrial effluents is still relatively low. Even though the production of C8-based PFAS has been phased out, they are still being detected at many WWTPs. Emerging PFAS such as GenX and F-53B are also beginning to be reported in aquatic environments. This paper presents a broad review and discussion on the occurrence of PFAS in municipal and industrial wastewater which appear to be their main sources. Carbon adsorption and ion exchange are currently used treatment technologies for PFAS removal. However, these methods have been reported to be ineffective for the removal of short-chain PFAS. Several pioneering treatment technologies, such as electrooxidation, ultrasound, and plasma have been reported for PFAS degradation. Nevertheless, in-depth research should be performed for the applicability of emerging technologies for real-world applications. This paper examines different technologies and helps to understand the research needs to improve the development of treatment processes for PFAS in wastewater streams. HIGHLIGHTS PFOA and PFOS are frequently detected in both WWTPs, in spite of their limited use.; Most PFAS in both WWTPs show negative removal rates.; GAC and ion-exchange resins are ineffective at removing short-chain PFAS.; Positive results for EOX, ultrasound, plasma, and new generation adsorbents.; Further studies are required for the practicability of emerging technologies at real scale.

Poultry slaughterhouses are generally large consumers of fresh water, which is exhausted as wastewater characterized by a high concentration of biological oxygen demand (BOD), chemical oxygen demand COD, and fats, oil, and grease (FOG). Cost-effective methods are required for the treatment of poultry slaughterhouse wastewater, with the aim of attaining a high quality effluent that can be reused in industrial processes to promote sustainability. As compared to conventional treatment methods, electrocoagulation is an efficient and low-cost system. Electrocoagulation is environmentally friendly, treating wastewater without the need of chemicals, thus limiting secondary pollution. The metal anodes initiate electrochemical reactions for coagulation and flocculation. Its distinct advantages include compact installation and simple operation. This paper offers a comprehensive review of recent literature that has been dedicated to utilizing electrocoagulation for poultry slaughterhouse wastewater treatment. This paper also examines aspects such as theory, potential applications, current applications, as well as economical assessment of the technique.

In recent years, research activities on water reuse applications have rapidly increased to manage natural water sources efficiently. Although these applications in centralized treatment systems can be effective, there are some drawbacks, including the economic factors for small settlements. In this study, a textile filtration unit with the integration of a sequencing batch reactor (SBR) was developed and different textile materials were used to enhance the treated effluent quality for reuse purposes. While the textile filtration unit alone could not effectively remove the pollutants, the removal efficiencies could not exceed 36% for COD and 50% for BOD5. However, SBR integration in to the filtration system improved the treated wastewater quality and COD and BOD5 reductions were obtained higher than 93%. Activated carbon coated cotton textile materials and activated carbon cloth, which was used for the first time for wastewater treatment, increased the treatment performance. In the filtration system, although the suspended solids were high in the SBR effluent, no clogging problem was observed even with higher operation times. This paper presents the research results on this textile filtration system, and experimental findings are discussed on the applicability of the system for small communities. HIGHLIGHTS Different textile cloths as low-cost materials were evaluated for wastewater treatment.; Activated carbon impregnated cotton textiles exhibited better treatment efficiencies.; Activated carbon cloth as an outer filtration material on the metal braided cotton textile showed remarkable reductions in all pollutants.; SBR integration enhanced the filtration unit performance.

Fish meal is used as feed for fish, dogs and cats, and in the pharmaceutical industry. Direct electro-oxidation has been used to treat fish meal industry effluent and organic pollutant removal, and was studied in this project. The anode used was titanium coated with ruthenium oxide and the cathode was stainless steel. In addition to organic pollutants, color removal was also studied. The varying parameter was current density, and those used were 10, 20, 27, and 34 mA/cm2. The effects of mechanical agitation and the inter-electrode distance on pollutant removal were also studied. The highest TOC and color removal (both 82%) were achieved at 34 mA/cm2, using mechanical agitation with 1.5 cm electrode spacing. Without agitation, TOC removal efficiency was 72%. The results show that electro-oxidation can be an effective secondary treatment for fish meal industry effluent. HIGHLIGHTS The electro-oxidation process to treat fish meal industry wastewater has been discussed.; The significance of using a mechanical agitator during the electro-oxidation process has been studied.; The efficiency of Ti/RuO2 anode in removing organic pollutants has been observed using a laboratory-scale batch reactor.; Different parameters such as current densities, inter-electrode spacing, and pH have been discussed in this paper.

This paper includes a comprehensive literature review of sludge composition data from wastewater treatment plants. 722 data sets from 249 sources were used to establish typical ratios between COD and solids-based parameters and to verify rule-of-thumb values, respectively. Confirmation of these typical ratios can also be accomplished by using biochemical composition data. It is shown that a correlation between data from proteins, lipids and carbohydrates analysis can be related to COD/VSS ratios. Finally, using the findings from the literature review, the organic and inorganic conversion factors of COD fractions in activated sludge models are adjusted to solids-based parameters. It was shown that with the adjustments of the factors and a partition of the particulate inert fraction into a fraction assigned to the influent and a fraction assigned to the endogenous products, a better agreement with the ratios of COD/VSS in the individual sludge streams can be established. HIGHLIGHTS Currently the largest collection of literature-based sludge data on municipal wastewater treatment plants.; Recommendations for adjustment of specific VS contents in model fractions of activated sludge models and further model improvements.; Linking biochemical data with typical wastewater parameters.

The marine algae Chaetoceros contains hexadecatrienoic acid, which suppresses methanogen development and improves the coulombic efficiency (CE) of microbial fuel cells (MFC). To inhibit the methanogens, optimum concentration of marine algae should be added to the anaerobic sludge to enhance the performance of MFC. A varying concentration of Chaetoceros ranging from 1 to 20 mg/mL was carried out for pretreatment of an anaerobic-mix consortium to suppress methanogens. MFC inoculated with pretreated anaerobic sludge with 10 mg/mL Chaetoceros showed a maximum power density of 21.62 W/m3 and a maximum CE of 37.25%, which was considerably higher than the treatment with other concentrations. At 10 mg/mL concentration, Tafel analysis of the anode in the MFC showed a higher exchange current density of 66.35 mA/m2 and a lower charge transfer resistance of 0.97 Ω.m2, revealing higher bio-electrochemical activity. The performance of MFC improved when the concentration of Chaetoceros was increased up to 10 mg/mL, but then began to decline as the concentration increased further. Thus, the optimum dose of Chaetoceros to be added in the mix-anaerobic consortium to optimize the power performance of MFC was determined, which can be carried out in scaled-up MFCs. HIGHLIGHTS Coulombic efficiency has improved to 37.25 at a dose of 10 mg/mL Chaetoceros sp. dosing.; A maximum power density of 21.62 W/m3 could be obtained at a concentration of 10 mg/mL of Chaetoceros sp.; A higher exchange current density of 66.35 mA/m2 was obtained at the optimum concentration.; The dosing was found to be sustainable at the optimum dosing.; Specific methanogenic activity was found to be less at the optimum dose.

This study investigated the efficacy of using micro-flocculation as a pretreatment approach in alleviating ultrafiltration (UF) membrane fouling caused by organic matter in treated wastewater. Three typical model dissolved organic matters (DOM), humic acid, fulvic acid, and sodium alginate, were employed to simulate membrane fouling. The results showed that micro-flocculation using poly aluminum chloride (PAC) or polymerized ferric sulfate (PFS) as flocculant could effectively enhance the treatment performance of the UF process on DOM. With 6 mg/L PAC, the removal efficiency of humic acid, fulvic acid, and sodium alginate by micro-flocculation combined UF process reached 79.95%, 63.25%, and 51.14%, respectively. Specifically, after micro-flocculation, micromolecular hydrophilic organic matter (e.g., fulvic acid) tended to form a compact cake layer. The macromolecular hydrophobic organic matter (e.g., humic acid) and macromolecular hydrophilic organic matter (e.g., sodium alginate) generally led to a loose cake layer. At PAC dosage of 6 mg/L, the membrane specific flux (J/J0) at the end was improved by 11.71%, 10.27%, and 2.2% for humic acid, sodium alginate and fulvic acid solutions, respectively, compared with the UF process alone. It could be inferred that micro-flocculation pretreatment can effectively mitigate the membrane fouling when treating wastewater containing humic acid, sodium alginate, or fulvic acid. HIGHLIGHTS Micro-flocculation could enhance the capability of the UF process in removing DOM.; Micro-flocculation pretreatment effectively alleviated UF membrane fouling.; Cake layer played an important role in mitigating UF membrane fouling.; The compactness of cake layer was related to the molecular weight, hydrophilicity or hydrophobicity of organic matters.

As natural organic matter (NOM) can cause serious ultrafiltration (UF) membrane fouling, most previous studies on UF fouling caused by NOM focused on the contribution of NOM characteristics. In this study, the correlation of molecular weight and fluorescence characteristics was examined and the fouling behavior of NOM was examined in a comprehensive manner through a lot of analysis including redundancy analysis (RDA), parallel factor analysis (PARAFAC) and atomic force microscopy (AFM). The results showed that NOM from Tong Xin river was composed of humic acid (500 Da–8,000 Da), tryptophan-like substance, soluble microbial product (SMP) and aromatic protein (600,000 Da–2,000,000 Da). Notably, UF performance was significantly affected by the humic acid-like substance. Concurrently, the combined mechanism (CM) model was adopted to evaluate the fouling mechanism of NOM. The results indicated that the cake-intermediate model played an important part during membrane fouling and the cake layer fouling had a larger predominance over the intermediate blocking, which can be further proved in the membrane morphology detection. HIGHLIGHTS The correlation of fractions with different molecular weight and fluorescent components was examined.; Fouling potential of NOM fractions was ranked by RDA analysis.; Humic acid like substance was the most detrimental foulant in the experiments.; The cake-intermediate fouling played the domain part in UF fouling.

Increased pollution caused by socio-economic development has led to compound-contaminated high-hardness water pollution. In this study, laboratory-scale nanofiltration (NF) treatment of such water was investigated. Response-surface methodology was used to optimize the NF operating parameters, and a regression model with desalination rate and transmembrane pressure changes as response values was established. The NF membrane efficiencies in contaminant removal from groundwater and surface water with compound-contaminated high hardness and the membrane-fouling characteristics during long-term operation were investigated. The results show that the optimal operating parameters for the NF membrane in the removal of inorganic salts from groundwater are as follows: influent pH 8, influent pressure 1 MPa, and water yield 27.976%. The removal rates for groundwater total hardness, total alkalinity, total soluble solids, K+, Na+, Ca2+, Mg2+, , Cl−, , and were 99.4, 90.3, 84.7, 63.2, 56.8, 99.6, 95.2, 99.6, 68.3, 86.1, and 65.9%, respectively. Surface water contains more complex components; therefore, membrane fouling during surface water is more serious. The NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling. HIGHLIGHTS Response-surface methodology was used to optimize the NF operating parameters.; NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling.; The membrane fouling by hardness ion was analyzed by SEM-EDS.

The use of agricultural waste materials to remove heavy metals from wastewater is attractive due to its simplicity and economic efficiency. In this study, the applicability of calcined eggshell waste materials (CES) for heavy metals removal from real wastewater were examined via transport column experiment preceded by coagulation/flocculation process.A column packed with granular activated carbon (GAC) is operated in parallel to CES column to evaluate the adsorptive attributes of CES. The findings are assessed from another set of column experiments consisting of sand followed by CES column to evaluate the effect of particulate matter (PM) on CES performance toward heavy metals removal. In coagulation experiment, alum addition at an optimum dose (3.0 g/L) reduced the total suspended solids (TSS) by 80%, whereas the Fe, Pb, Zn, Cu, Ni, and Cr were reduced by 80%, 77%, 76%, 73%, 56%, and 49%, respectively. Under the current applied hydrodynamic conditions, using sand column before CES column improved the removal efficiencies of Fe, Pb, Cu, Zn, Ni, and Cr from 50% to 92%, 55% to 93%, 60% to 87%, 53% to 76%, 45% to 65%, and 41% to 60%, respectively. The whole results illustrate that CES can be competitive to GAC for heavy metals removal from landfill leachate, mainly if applied after PM removal by sand filtration. HIGHLIGHTS Total suspended solids and heavy metals are effectively decreased by adding 3.0 g/L alum.; Heavy metals are effectively eliminated from landfill leachate using calcined eggshells.; Particles facilitated heavy metal movement via the filter media.; Sand pretreatment improved the performance of calcined eggshell to remove heavy metals.; The research findings may lead to more cost-effective landfill leachate treatment technology.

Pretreatment is an indispensable means to alleviate membrane fouling and improve ultrafiltration (UF) performance. In this study, we designed and established a powder-activated carbon pre-coating membrane (PACPM) unit as a pretreatment for the UF system. The effective filtration area of PACPM was 0.5 m2. 300 g/m2 PAC was selected as the optimal dosage in the pilot-scale apparatus according to the laboratory-scale trial. The pre-coating membrane could be formed within 30 min. PACPM could remove different kinds of organic compounds with different molecular weights and hydrophobicity during a certain period of time. During 10 operation cycles, the specific flux decrease rate of PACPM-UF was only 2.8%, which was much lower than that of direct UF (13.4%). PACPM could improve the performance of the UF system, not only for the increase of the initial SF value but also for the increase of the flux recovery thorough backwash. Nevertheless, a regular replace-regeneration process is necessary to maintain PACPM performance. HIGHLIGHTS The pilot-scale powder-activated carbon pre-coating membrane (PACPM) unit was designed and established.; The pre-coating membrane could be formed in a short time.; PACPM-UF had a better efficiency of contaminant removal than direct UF.; PACPM could improve the performance of the UF system treating the municipal wastewater treatment plant effluent.

An autopsy of spiral wound reverse osmosis (RO) membrane operated in brackish water treatment was conducted to understand the origin and extent of foulants and fouling mechanisms. Structural and chemical characterization was determined by visual inspection and instrumental analysis such as scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). It was observed that the membrane surfaces were completely covered with a gray/brown pollutant layer in all membrane sheets. SEM images proved accumulation of mineral pollutants on membrane surface. Also, high levels of Al and Si, which were attributed to aluminum silicates originating from feed water, were determined on membrane surfaces. Additionally, the XRD analysis results showed that the foulant sample collected from membrane surfaces included halloysite, SiO2 and LiCl components. Fujiwara's result proved that no damage occurred on the membrane surface due to oxidation. Consequently, a fouling control strategy for RO-based brackish water treatment plants was also recommended to increase the membrane life. HIGHLIGHTS An autopsy of spiral wound RO membrane operated in brackish water treatment was conducted to understand the fouling behaviors.; Various instrumental and analytical analyses were performed to characterize the organic and inorganic foulant on membrane surface.; A fouling control strategy for RO-based brackish water treatment plans was also recommended to increase the membrane life.

Drinking water consumption is essential to maintain a good quality of life, but it is not available for all communities. Therefore, this work aimed to develop an alternative and accessible process for water treatment, based on filtration and solar disinfection, and evaluate it in both bench and pilot scales. The construction cost of the system was estimated and compared with other available options so that its economic viability could be discussed. For this purpose, water from a stream was collected and analyzed. A filter made of PVC tubes, sand, and gravel was built, acting, respectively, as a column, filtering medium, and support layer. As for the disinfection process, the SODIS (Solar Water Disinfection) methodology was adopted. The water was exposed to the sun, and the best exposure time was determined based on the analysis of total coliforms and E. coli. Finally, a prototype was built for a flow rate of 37.5 L d−1, consisting of two filters operating at a filtration rate of 2.38 m3 m−2 d−1. About 97% turbidity removal was obtained, as well as 99.9% for total coliforms and 99.1% for E. coli. It is estimated that the cost of building a water treatment system for one person is approximately USD 29.00. HIGHLIGHTS On pilot-scale tests, slow filtration showed high efficiency on bacteria removal, which indicates that a biological layer was formed during the operation.; The SODIS treated water should be stored at a low temperature or used as soon as possible, due to the bacteria regrowth process that can occur overnight.; The system costs around 116 USD for a four-people house, which is considered affordable for low-income families.

Industrial effluents are usually one of the major industries polluting the environment and surface water. It is estimated that the worldwide production of dyes is about 70 tons/year. To overcome this problem, innovative processes are suggested for the treatment of industrial effluents containing dyes and heavy metals. The goal of the processes is often to reduce the toxicity of these pollutants in order to meet treatment standards. Recently, great attention has been paid to innovative processes for physical and chemical removal techniques such as adsorption on new adsorbents, biomass adsorption, membrane filtration, irradiation, and electrochemical coagulation. In this study, the application of adsorbents in the adsorption process to remove dye pollutants from industrial effluents has been studied. Factors affecting dye adsorption such as pH, temperature, initial dye concentration, and adsorbent amount are also presented. The obtained results revealed that more than 80% of the dye adsorption on the surface of adsorbents are endothermic processes and more than 95% of the processes obey the pseudo-second-order kinetic model. HIGHLIGHTS Investigation of the influence of different adsorbents and different adsorption process parameters.; Factors affecting dye adsorption.; Regenerability of adsorbents in the adsorption process to make the adsorption process more economical.; Application of adsorbents in the adsorption process to remove dye from industrial effluents.

This study employs a novel combined pilot plant consisting of an anaerobic reactor followed by a membrane electro-bioreactor (eMBR) to treat domestic water containing selected micro-pollutants of emerging concern (CECs) [ibuprofen (IB), carbamazepine, diclofenac (DCF) and 17α-ethinylestradiol (EE2)]. The first phase operated as a conventional membrane bioreactor to achieve the removal of organic matter [chemical oxygen demand (COD)], the CECs and phosphorus. A removal rate of 96.3% for COD, 94.5% for IB, 37.1% for CMZ, 87.1% for DCF and 96% for EE2 was obtained. In the three subsequent phases, current density (CD) of 5, 10 and 15 A/m2 was applied successively in the eMBR with the aim of investigating the effects on the removal of the former components and the fouling of the membrane. After the application of 5 and 10 A/m2 CD, the removal rate of COD decreased. Regarding phosphorus, a CD of 5 A/m2 was enough to achieve the rate of 97% and the membrane fouling suffered a substantial reduction too. Finally, the experimental results were subject to statistical analysis using the Kruskal–Wallis and Wilcoxon tests to validate the influence of each DC. The research was funded by the Ministry of Economy and Competitiveness of Spain through the project ‘Elimination of emerging pollutants through serial anaerobic and aerobic processes and complementary treatments: combined system UASB + eMBR + O3/AC CTM2016-76910-R, and by the Generalitat Valenciana through a Santiago Grisolía grant, ref GRISOLIAP/2017/173.

Reverse osmosis concentrate (ROC) is one of the major drawbacks in membrane treatment technologies specifically due to the scale-forming ions. It is important to remove these ions from ROC to enhance total water recovery and reuse in the textile industry that is the largest water-consumer and polluter industry. In this work, coagulation/high pH precipitation (CP) integrated with ceramic microfiltration (CMF) was studied as a pre-treatment method followed by nanofiltration (NF) to increase the efficiency of water recovery. To prevent organic fouling, ferric chloride (FeCl3) was applied at a concentration of 3 mM, and ceramic membranes were used for the removal of non-precipitating crystals and/or suspended solids (at high pH) before the NF processes. The CP-CMF method successfully removed calcium (Ca2+), magnesium (Mg2+), silica (SiO2), and TOC up to 97, 83, 92, and 87% respectively, which resulted in higher performance of the NF process. Moreover, this method provided higher flux at lower pressure that ultimately increased overall water recovery of the NF process to achieve near-zero liquid discharge (n-ZLD). A cost–benefit estimation showed that a high-quality effluent (COD

Microbial phosphate removal from wastewater sewage is a promising and feasible technique that increases the ability of a sewage treatment system to remove phosphate from wastewater. Maintaining a healthy population of phosphate-solubilizing bacteria is the key premise of biological sewage treatment. Chitosan is used to remove dissolved phosphorus from the water column during wastewater treatment. The present study found that chitosan has another function in phosphorus removal, affecting the diversity and community composition of phosphate-solubilizing bacteria. We obtained 16S rRNA genetic data by using a shotgun metagenomic sequencing method. Data indicated that phosphate-solubilizing Pseudomonadaceae was the dominant bacteria population, after adding chitosan to the dynamic water treatment process. In chitosan-enhanced treatments, populations were 35.11% larger than the control group. Chitosan addition also caused some increases in the population sizes of Rhodocyclaceae, Bacillaceae, and Enterobacteriaceae, but the addition of chitosan had little effect on Hyphomicrobiaceae and Sphingomonadaceae in the activated sludge. Moreover, the Chao1 estimator, the abundance-based coverage estimator (ACE), and Shannon index all indicated a very high diversity of bacteria when chitosan was added. Finally, we determined that chitosan increased the activity of the enzymes phytase, dehydrogenase, and phosphatase, which enhance the degradation rate of phosphorus in the activated sludge of a D-A2O system. We suggest that chitosan plays an important role in dissolving organophosphorus during sewage treatment. HIGHLIGHTS We report that we found another function of chitosan, that is, chitosan could affect the bacterial diversity and community composition in wastewater treatment.; We solved the problem that to increase the total phosphorus removal efficiency of biological nutrient removal process for wastewater treatment in low temperatures.

Moringa Oleifera (MO) is a highly effective conditioner in the dewatering of Fecal sludge (FS). However, the model for the prediction of its optimal dose has not yet been documented. This article presents the results of the developed model for the prediction of MO optimal doses. The developed model was based on assessing the FS parameters and MO stock solution. The FS samples were obtained from a mixture of a pit latrine and septic tank and were analyzed at the water quality laboratory of the University of Dar es Salaam. The multiple linear regression model was used to establish a relationship between MO optimal dose as a function of FS characteristics (pH, Electrical Conductivity, Total Solids and Total Suspended Solids) and concentration of MO stock solution. The results indicated that the main contributing factors which determine the MO optimal dose were the concentration of MO stock solution, followed by pH of FS. The model results showed a good agreement between the predicted and observed MO optimal dose with a coefficient of determination of R2 = 0.72 and 0.9 for calibration and validation respectively. Therefore, the model can be adapted to determine the MO optimal dose without running the Jar-test experiment.

The process operation of wastewater treatment plants (WWTPs) is based on the proper set up of several physical, chemical and biological parameters. Often, issues and problems arising in the process are strictly linked to the rheological behaviour of sewage sludge (SeS). Therefore, rheological measurements, which recently have captured a growing interest, represent an important aspect to consider in the design and operation of WWTPs, especially in the sludge-handling processes. The knowledge of rheological behaviour of SeS represents a crucial step to better understand its flow behaviour and therefore optimize the performance of the processes, minimizing the costs. The SeS are non-Newtonian fluids and, to date, Bingham and Ostwald models are the most applied. This work presents an overview of scientific literature about the rheological properties of SeS and discusses the importance of its knowledge for the management of WWTPs.

The management and disposal of excess sludge are emerging issues owing to the high costs associated with treatment. In this study, the viability of a modified bentonite was investigated as a conditioning agent for the stabilisation of heavy metals (i.e., Cu, Zn, Cr, Pb, and Cd) and the retention of nutrient species (i.e., total nitrogen (TN), total phosphorus (TP), available nitrogen (available N), and Olsen-phosphorus (Olsen-P)) in sewage sludge for agricultural use. Five grams of modified bentonite resulted in the highest stabilisation rate of heavy metals and strongly contributed to the stabilisation of heavy metals. However, increased amounts of modified bentonite might increase the TN, available N, and TP losses in the conditioned sewage sludge. Through the analytic hierarchy process modelling, optimal concentrations of nutrient species and heavy metals remaining in the conditioned sewage sludge were achieved when the ratio of bentonite to sewage sludge was 1:12.5 (4 g bentonite : 50 g sludge). Moreover, the optimal mixing ratio of the conditioned sewage sludge to the soil (1:2) was suggested for agricultural use. Based on these observations, modified bentonite allowed the sewage sludge to be used as a fertiliser in agriculture by stabilising heavy metals and retaining nutrient species. HIGHLIGHTS The modified bentonite stabilised the heavy metals and retained the nutrient elements in the sewage sludge.; The AHP modelling revealed the optimal ratio of bentonite to sewage sludge (4 g bentonite : 50 g sludge).; The optimal mixing ratio of the conditioned sewage sludge to the soil (1:2) was suggested for agricultural use.; The modified bentonite allowed sewage sludge to be used as a fertiliser in agriculture.

This work presents a compact plant's development and performance evaluation for the decentralized treatment of domestic sewage. The plant was conceived and installed in a house with four residents in Vicente Pires, Federal District, Brazil. Its purpose was to remove organic matter and solids using a low-cost biological treatment process that was simple to operate. The plant was essentially anaerobic, composed of an up-flow anaerobic reactor and an anaerobic filter, both associated with lamella settlers. It was operated under real conditions and monitored for nineteen months, with removal efficiencies (calculated over the medians) of 81% for COD, 83% for BOD, 51% for Total Solids, 55% for Total Volatile Solids, 87% for Total Suspended Solids, and 100% for Settleable Solids. The plant performed adequately, with no clogging between the plates of the lamella settlers, no offensive odours, and limited amounts of sludge and scum.

A combined system of an anaerobic baffled reactor (ABR), a down-flow hanging sponge (DHS) reactor, an aquarium tank (AT), and a constructed wetland (CWL) was proposed as a new concept for sewage treatment. The ABR and DHS reactor, AT, and CWL were applied for biological sewage treatment, bioassay, and nutrient removal with food production, respectively. Killifishes and tomatoes were cultivated in the AT and CWL, respectively. In the ABR, 81.3% of total chemical oxygen demand and 76.5% of total biochemical oxygen demand were removed at 5.1 h of hydraulic retention time (HRT). Most remaining organic matter and 47.1% of ammonia were removed in the DHS reactor. In the CWL, 97.0% of total inorganic nitrogen and 78.6% of phosphate were removed with 3.87 kg/m2 of tomatoes producing yield at 4.4 days of HRT. In addition, anaerobic ammonium-oxidizing bacteria Candidatus Scalindua and ammonia-oxidizing bacteria Nitrospira and Nitorosococcus were considered as contributors to nitrogen removal in the CWL. The final effluent's water can be utilized as recycled water by installation of sand filtration and disinfection processes. Therefore, the proposed system can be applied as a low-energy, low-cost sewage treatment system with direct resource recovery. HIGHLIGHTS Anaerobic baffled reactor removed most of organic matters in sewage directly.; Foods for killifishes were automatically fed by sewage treatment.; Nutrients in sewage were consumed by tomatoes in constructed wetland.; Proposed system achieved direct resource recovery from sewage.

Effects of ballast water treatment by advanced electro-catalysis oxidation processes (AEOP) on abundance, activity, and diversity of marine bacteria were examined in a full-scale ballast water management system (BWMS) at Yangshan Port, Shanghai, China. Water samples were collected immediately after treatment and at discharge to evaluate the contingency treatment performance of the BWMS for bacteria. After treatment, the total viable count reduced to 0.7 × 104 CFU·mL−1, and both Escherichia coli and enterococci decreased to 10 CFU·100 mL−1, which satisfied the D-2 Standard of the International Maritime Organization. AEOP can be as an effective contingency reception facility. Sequencing of 16S rRNA gene amplicons demonstrated the declining trend in bacterial diversity, and while the treatment did not completely eliminate the risk of bacterial dispersal, potentially pathogenic bacteria survived in treated and discharged samples. Bacterial diversity is of greater concern when evaluating effects of ballast water treatment on microorganisms because the bacteria which can develop adaptive mechanisms to environmental change will have a greater potential for invasion in the new environment. HIGHLIGHTS Using high-throughput sequencing based on V4–V5 region of 16S rRNA genes.; AEOP can be considered as effective ballast port contingency reception equipment.; The treatment cannot completely eliminate the risk of pathogen spread.; Bacteria that develop adaptive mechanisms have a greater potential for invasion.; Diversity is better than density of bacteria in indicating effects of treatment.

Industrial wastewaters are recognized as a valuable resource, however, their disposal without proper treatment can result in environmental deterioration. The associated environmental/operational cost of wastewater treatment necessitates upgrade of applied processes towards the goals of sustainability and mitigation of climate change. The implementation of cyanobacteria-based processes can contribute to these goals via resources recovery, production of high-value products, carbon fixation and green-energy production. The present study evaluates the cyanobacterium Synechococcus elongatus PCC 7942 (S7942) as a biological component for novel and sustainable alternatives to typical biological nutrient removal processes. Valuable results regarding cultivation temperature boundaries, applied disinfection techniques and analytical methods, as well as regarding relations between parameters expressing S7942 biomass concentration are presented. The results show that at typical industrial wastewater temperatures, S7942 efficiently grew and removed nitrates from treated snack-industry's wastewater. Moreover, in cultures with treated and relatively saline dairy wastewater, its growth rate slightly decreased, but nevertheless nitrates removal rate remained efficiently high. A comparison between typical denitrification processes and the proposed nutrient removal process indicated that a S7942-based system may constitute an alternative or a supplementary to denitrification process. Thus, Synechococcus elongatus PCC 7942 proved to be a potent candidate towards sustainable industrial wastewater treatment applications. HIGHLIGHTS Synechococcus elongatus PCC 7942 efficiently grows in treated industrial wastewater.; High rates of nitrates removal and growth at typical wastewater temperatures.; Efficient growth and high nitrates removal in saline industrial wastewater.; Filtration coupled with chlorination/dechlorination is effective for pre-treatment.

Alternative sanitising agents are required in the fruit and vegetable processing industry, capable of effectively disinfecting both the product and the washing water to increase its reuse, while not producing harmful by-products like chlorine-based agents. In the present work, electro-oxidation (EO) and ozone are proposed for vegetable process water reuse, being optimised for their individual and combined application. The application of hybrid electro-oxidation and ozone achieved 7 log reduction after 15 min of treatment in batch using boron-doped diamond (BDD) as anode material, showing important synergistic effects when compared with the individual treatments. When the process was applied in continuous mode, up to 6 log reduction of total bacteria was achieved using EO alone with Ru as the anode and stainless steel as the cathode, under 11 mA/cm2 of current density, a cell retention time of 12 s and no addition of chemical reagents (electrolyte). Under these conditions, the absence of microorganisms in water was maintained for more than 24 h, no harmful by-products (chlorate, bromate) were detected and no damage to lettuce seeds were observed when evaluating water reuse potential. HIGHLIGHTS EO and O3 for water reuse in the fruit and vegetable process sector.; Lettuce washing water was used to test the technology at laboratory scale.; The novelty lies in the application of the combined treatment for disinfection and water reuse.; 7 log reduction after 15 min in batch and up to 6 log reduction in continuous mode were achieved.; Cost reduction in terms of electrode price and durability would allow an easy up-scaling.

Intense pressure on water resources has led to efforts to reuse reclaimed processing wastewater in the food industry. There are tight rules for water quality, but efficient separation technologies such as reverse osmosis possess good possibilities for water reuse. This study developed a membrane-based reuse water concept for wastewater from the candy industry emphasizing the pre-treatment stage in the concept to reduce fouling. The wastewater contained suspended solids, sugar compounds and the ingredients for candy gelation, which had a tendency to foul membranes, making pre-treatment essential for a successful concept. Cross-rotational ultrafiltration, which featured enhanced fouling prevention for membranes, functioned well for the removal of challenging substances. Conventional filtration technologies were impractical due to a low flux, even when the viscosity of the wastewater was reduced using surfactants. The wastewater had a high chemical oxygen demand, meaning that there was a strong fouling potential for reverse osmosis membranes, but also high osmotic pressure. A spiral wound reverse osmosis functioned well when the wastewater was pre-treated, and it produced good quality water with respect to all the other studied parameters except the chemical oxygen demand. However, chemical oxygen demand rejection was 99% since the concentration in the wastewater was originally very high. HIGHLIGHTS A membrane-based concept was successfully applied for water reuse from wastewater.; Cross-rotational ultrafiltration technology enabled chemical-free pre-treatment for wastewater.; Spiral wound reverse osmosis achieved good filtration performance with developed pre-treatment.; Techno-economic evaluation is available for the functional concept.

A batch test procedure was investigated to provide insight into the microbial contribution to disinfectant decay in drinking water distribution systems using chloramines. A modified method for determining the critical threshold residual (CTR), the intersection point on a semi-log plot between first-order total chlorine fitted decay curves before and after the breakpoint, was developed. Unlike the CTR as originally defined, initial sample conditions were retained rather than artificially raising the monochloramine concentrations. The CTR calculated with this modified method can more easily be applied to distribution system scenarios. In addition, four types of decay curves were identified and could distinguish differences in the microbial contribution to disinfectant residual decay. This study revealed that chloramine decay batch tests should be evaluated based on decay curve type, decay rates, and the CTR value, in addition to the microbial decay factor, which has been used alone in previous studies. The batch test approach and evaluation criteria established here can be used to predict conditions favorable for rapid chloramine decay and nitrification, and that monitoring and control strategies should be implemented. HIGHLIGHTS The developed batch test procedure distinguishes between chemical and microbial contributions to chloramine decay and determines nitrification potential.; The critical threshold residual (CTR) was identified as the intersection of fitted first-order total chlorine decay curves before and after a breakpoint.; Batch tests were evaluated by decay curve type, decay curve rate, CTR, and microbial decay factor.

In this study, an oxygen-releasing and phosphorus-controlling agent (ORPC) consisting of calcium peroxide (CaO2), bentonite, cement, stearic acid (SA), citric acid (CA) and fine sand was synthesized successfully and used to purify phosphorus-rich river water. The removal of phosphorus using ORPC was studied in actual river water and the results found that over 75.0% phosphorus was removed by adding ORPC at 30 mL h−1 flow rate in initial phosphorus concentrations of 0.76 mg L−1. The ORPC was further used to evaluate the changes of aluminum phosphate (Al-P), ferric phosphate (Fe-P) and calcium phosphate (Ca-P) in sediment. Fe-P, Al-P, and Ca-P in the sediment increased from 0.14, 0.196, and 1.63 mg g−1 to 0.159, 0.372, and 2.74 mg g−1 respectively within 28 days, indicating that the total dissolved phosphorus in the overlying water could be adsorbed by ORPC and further transformed into Al-P, Ca-P, and Fe-P in the sediment, thus inhibiting the release of endogenous phosphorus in sediment to the water. In addition, the performance of ORPC with various contents of SA and CaO2 was investigated. In summary, ORPC can be employed to adsorb phosphorus in water and prevent phosphorus release from sediment, therefore achieving the purpose of controlling phosphorus and maintaining DO at a reasonable level.

The disposal of waste biomass generated from biological wastewater treatment plants is a costly process and poses environmental threats to the receiving environment. This study aimed to determine the suitability of algae and waste activated sludge (WAS) produced from a brewery effluent treatment system as a fertiliser in agriculture. The change in soil characteristics and the growth of a crop fertilised with algae or WAS was compared with a conventional inorganic fertiliser. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or WAS had a significantly higher mean biweekly yield (5.08 ± 0.73 kg/m2) when compared with the inorganic fertiliser control (3.45 ± 0.89 kg/m2; p < 0.0001). No difference was observed in the soil's physical fertility when algae or WAS were applied to the soil (p > 0.05). The nitrogen applied to the soil from algae and WAS biomass appeared to leach out of the soil less than the nitrogen supplied by inorganic fertilisers. The application of WAS or algae on soil increased the soil's sodium concentration and sodium absorption ratio from 774.80 ± 13.66 mg/kg to 952.17 ± 34.89 mg/kg and 2.91 ± 0.04 to 3.53 ± 0.13, respectively. Regulations on the application of algae or WAS on agricultural soils should be altered to consider the limit values for sodium. HIGHLIGHTS Swiss chard production was similar when fertilised with fertiliser, waste activated sludge or algae.; Anaerobically digested waste activated sludge and algae can replace inorganic fertiliser.; Waste activated sludge and algae increased the soil's sodium absorption ratio.; Soil application rates of sludge should consider sodium limit values.