Domestic Wastewater Effluent Research Articles

Green synthesis of magnetic chitosan composite hydrogel (Fe3O4@CS photocatalyst) for the solar light driven catalytic degradation of organic contaminants

Ecofriendly magnetic chitosan composite hydrogel (Fe3O4@CS photo-catalyst) was prepared by using an aqueous extract of Boerhevia procombens leaves for the solar light mediated catalytic degradation of lethal organic Congo red dye. The prepared composite hydrogel was structurally studied using Fourier transform infrared spectroscopy (FT-IR) which reveals the formation of the Fe3O4@CS photocatalyst. The X-ray diffraction (XRD) investigation of the composite hydrogel signified high crystallinity of photocatalyst and crystallite structure of 53 nm for magnetite nanoparticles (Fe3O4 NPs). The surface investigation suggests multilayered porous photocatalyst owing to the presence of cavities offering more photoactive sites for the photodecomposition of dye molecules. The energy dispersive X-ray (EDX) scanning supports the fabrication of Fe3O4@CS photocatalyst due to the perseverance of carbon, nitrogen, oxygen, and iron. The thermogravimetric analysis (TGA) together with vibrating sample magnetometry (VSM) certifies the preparation of thermally stable and magnetic composite hydrogel. The fabricated Fe3O4@CS photocatalyst possess low bandgap energy of 2.36 eV, supporting the excellent disintegration of dye molecules in the sunlight irradiations. The photocatalyst exhibited a maximum degradation efficacy of 99.1% for Congo red dye in the solar light irradiations with refined states of 70 min radiation time, dye concentration of 20 mg/L, pH 6, and 200 mg photocatalyst amount obeying the second-order kinetic model (R2 = 0.9959). The Fe3O4@CS photocatalyst displayed a little decrease in dissociation efficiency of dye molecules after five repeated cycles owing to the coverage or rupturing of photoactive sites. Conclusively, the results support Fe3O4@ CS to be an economical and biocompatible magnetic catalyst for the catalytic decontamination of Congo red dye molecules and other organic contaminants in domestic and industrial wastewater effluents.

Removal of major nutrients by sono-direct and sono-alternate current electrocoagulation process from domestic wastewater

Background: Electrocoagulation is becoming a promising eco-friendly wastewater treatment technique. It is a low-cost wastewater treatment method suitably applied for various wastewater effluent characteristics. Nevertheless, there are different kinds of electrocoagulation; comparison among them in terms of nutrient removal is investigated in the present research. This study analyzed nitrate (NO3 - ) and phosphate (PO4 3-) removal potential of the sono-alternative and direct-current electrocoagulation process. Methods: Batch reactor and sono-direct current (SDC)/sono-alternative current (SAC) electrocoagulation cell were employed to investigate NO3 - and PO4 3- removal efficiency from domestic effluents. The data gathered from laboratory experiments were analyzed using response surface methodology (RSM). ANOVA was used to examine the interaction effects of diverse parameters in terms of NO3 _ and PO4 3- removal from domestic wastewater effluents. Results: At extreme experimental conditions, the percentage of NO3 - and PO4 3- removal attained with sono-direct current electrocoagulation (SDCE) and sono-alternative current electrocoagulation (SACE) were 96.5%, 96.2% and 96.8%, 96.5, respectively. The SACE was more successful in eliminating NO3 - and PO4 3- than the SDCE process. The appearance of resistant oxide coating on the cathode and the appearance of corrosion on the anode due to oxidation processes in the case of SDCE were identified as principal factors highly affecting NO3 - and PO4 3- removal efficiency. Conclusion: With optimum process efficiency, experimental findings show that the SACE process is more capable of NO3 - and PO4 3- removal than the SDCE process.

Contamination of Bisphenol A, Nonylphenol, Octylphenol, and Estrone in Major Rivers of Mega Manila, Philippines.

Endocrine-disrupting compounds (EDCs) such as natural and synthetic hormones as well as phenolic industrial chemicals are considered contaminants of emerging concern in environmental waters. While EDCs carried through rivers may impact ecosystem health and productivity, these compounds are still not widely studied nor regulated. In the present study, we report the occurrence of EDCs in urban rivers in Mega Manila, namely, the Marikina, Pasig, Angat, and Pampanga Rivers that drain into Manila Bay. Endocrine-disrupting compounds may have reached these rivers through domestic wastewater and industrial effluents. Water samples from the rivers were extracted by solid-phase extraction before instrumental analysis using a liquid chromatograph coupled to a mass spectrometer. The analytical method exhibited good linear response (>99% in the concentration range of 1-50 µg/L) and low instrument detection limits (0.14-1.46 µg/L) for the hormones estrone (E1), estradiol, ethinylestradiol, progesterone, and testosterone, and the industrial chemicals bisphenol A, nonylphenol, and octylphenol. Of the hormones, E1 was detected up to 11 ng/L. Bisphenol A, nonylphenol, and octylphenol were measured up to 54, 1878, and 62 ng/L, respectively. Endocrine-disrupting compounds are not yet monitored in water bodies in the Philippines and there are no local guidelines yet on occurrence, pollution prevention, and mitigation. Environ Toxicol Chem 2024;43:259-266. © 2023 SETAC.

Seasonal Variations in Surface Water Quality in River Njoro and Lake Nakuru, Kenya

Water pollution from rivers and lakes has resulted in serious environmental issues on a global scale. The public's growing concern over the decline in river and lake water quality makes it more important than ever to assess the water quality of these bodies of water over a prolonged period of time. During the rainy and dry seasons of 2022, 120 water samples were collected from 5 monitoring stations located within River Njoro and Lake Nakuru. The samples underwent physicochemical analysis of selected water parameters, which included salinity, temperature, pH, turbidity, total nitrogen (TN), total phosphorus (TP), electric conductivity (EC), and total dissolved solids (TDS). The results were compared using the National Environmental Management Authority (NEMA) of Kenya's guidelines and the results showed that the water quality of the Njoro river and Lake Nakuru fluctuated with the seasons, particularly in the lower water column of river Njoro. The quality parameters had the following values; EC values range between 73.33 ± 0.55 μs/cm - 533.33 ± 0.64 - μs/cm, respectively for both seasons; Salinity values range from 0.085 ± 0.02 ppt - 2.59 ± 0.03 ppt; pH values were between 8.8 – 9.3; Temperature was 23.69 ± 0.07 °C – 14.22± 0.07°C; Turbidity varied significantly – 13.95 ± 0.27 NTU - 36.03 ± 0.35 NTU; TDS between 46.67 ± 0.11 ppm- 243.33 ± 0.04 ppm; TN ranges between 5.97 ± 3.24 mg/L - 8.57 ± 3.18 mg/L and TP 7.49 ± 1.7-9.41 ± 1.84 mg/L in the dry and rainy seasons, for River Njoro and Lake Nakuru respectively. This study showed that the degree to which human activity affects water quality varies with the season. Therefore, most of these factors should be considered while controlling rivers downstream in order to ensure the health of aquatic life, also it is essential to increase lake water quality monitoring and regulate human activity. Additionally, the results revealed that water pollution resulted primarily from domestic wastewater, agricultural runoff and industrial effluents.

Feasibility of Water Quality from Treated Domestic Wastewater Effluent in Bojongsoang WTTP, Bandung District for Fish Farming

Bojongsoang Wastewater Treatment Plant (WTTP) is a place for processing wastewater in domestic activities in Bandung City, West Java, Indonesia before being released into the aquatic environment. This study aims to determine the feasibility of water quality from domestic wastewater treatment for fish farming activities at the Bojongsoang WTTP in January - June 2023. The survey method was used with purposive sampling technique and conducted at five research stations with two replicates. The efficiency of reducing sewage treatment at the Bojongsoang WTTP is able to reduce the BOD5 value by 73%, reduce ammonia by 66%, reduce TSS by 38%, increase DO by 75% and the temperature and pH parameters are stable as expected. The results of testing six water quality parameters from processed domestic wastewater at the Bojongsoang WTTP, some ponds are at high levels and exceed water quality standards. So that it is not suitable if it is used as a fish farming pond that will be consumed or traded. The performance of each WTTP treatment pond is not yet optimal in accordance with the aims and objectives of wastewater treatment (WTTP), namely to reduce (eliminate) polluting substances so that they can be used for agricultural and fishery needs.

Characterisation of ChE in Solea solea and exposure of isoflavones in juveniles of commercial flatfish (Solea solea and Solea senegalensis).

The isoflavones genistein and daidzein are flavonoid compounds mainly found in legumes, especially in soybeans and their derived products. These flavonoids can be present in agricultural, domestic and industrial wastewater effluents as a result of anthropogenic activities and may be discharged in the environment. Due to the large growth of the aquaculture sector in recent decades, new and cost-effective fish feeds are being sought, but there is also a particular need to determine the effects of exposed flavonoids on fish in the aquatic environment, as this is the main route of exposure of organisms to endocrine disruptors. This study evaluated the possible effects of these isoflavones on juveniles of Solea senegalensis and Solea solea. After 48-96 h of exposure, the acetylcholinesterase activity in the sole head tissues was measured, and the cholinesterase activity in juveniles of common sole (S. solea) was determined. Experiments were carried out to determine the optimal pH, investigate the specificity of three substrates (acetylthiocholine, butyrylthiocholine, propionylthiocholine) on cholinesterase activity and determine the kinetic parameters (Vmax and Km ). The results obtained showed that neither genistein nor daidzein exposure to S. senegalensis and S. solea inhibited the activity of acetylcholinesterase at the tested concentrations (genistein: 1.25, 2.5, 5, 10 and 20 mg/L; daidzein: 0.625, 1.25, 2.5, 5 and 10mg/L).

Microbial Populations Occurrence in the Domestic Wastewater and Food Industry Effluents

Microbial Populations Occurrence in the Domestic Wastewater and Food Industry Effluents

Polishing wastewater effluent using plants: floating plants perform better than submerged plants in both nutrient removal and reduction of greenhouse gas emission.

While research on aquatic plants used in treatment wetlands is abundant, little is known about the use of plants in hydroponic ecological wastewater treatment, and its simultaneous effect on greenhouse gas (GHG) emissions. Here, we assess the effectiveness of floating and submerged plants in removing nutrients and preventing GHG emissions from wastewater effluent. We grew two species of floating plants, Azolla filiculoides and Lemna minor, and two species of submerged plants, Ceratophyllum demersum and Callitriche platycarpa, on a batch of domestic wastewater effluent without any solid substrate. In these systems, we monitored nitrogen and phosphorus removal and fluxes of CO2, CH4 and N2O, for 2 weeks. In general, floating plants produced the most biomass, whereas submerged plants were rapidly overgrown by filamentous algae. Floating plants removed nutrients most efficiently; both floating species removed 100% of the phosphate while Lemna also removed 97-100% of the inorganic nitrogen, as opposed to a removal of 81-88% in submerged plants with algae treatments. Moreover, aquaria covered by floating plants had roughly three times higher GHG uptake than the treatments with submerged plants or controls without plants. Thus, effluent polishing by floating plants can be a promising avenue for climate-smart wastewater polishing.

Influences of Anthropogenic Pollution on the Dynamics of Sedimentary Fulvic Acid Fractions as Revealed via Spectroscopic Techniques Combined with Two-Dimensional Correlation Spectroscopy

To identify the influences of anthropogenic activities on the composition, spatial distribution, sources, and transformation mechanism of sedimentary fulvic acid (FA) fractions from different reaches of an urban river were tracked via excitation-emission matrix (EEM) fluorescence spectroscopy with parallel factor (PARAFAC) analysis and two-dimensional correlation spectroscopy (2D-COS). Sediment samples were collected from Baitapu River (BR) along gradients with human activities (e.g., rural, town, and urban sections) in Shenyang, northeast China, from which FA fractions were extracted and then determined via EEM fluorescence spectroscopy. According to optical indices, the autochthonous sources of sedimentary FA fractions in BR were more significant than the terrestrial sources. Among the sections, the contribution from autochthonous sources decreased in the following order: Rural > Urban > Town. Six components of sedimentary FA fractions were identified via EEM–PARAFAC: C1 comprised tryptophan-like (TRL) compounds; C2 was associated with microbial humic-like (MHL) compounds; C3, C4, and C5 were associated with FA-like (FAL) compounds; and C6 comprised humic acid-like (HAL) compounds. The proportion of sedimentary FA fractions decreased in the following order: MHL + FAL + HAL (humus, 77.37–88.90%) > TRL (protein, 11.10–22.63%) for the three sections, showing that humus dominated. The town section exhibited the highest sedimentary FA fractions (5328.87 ± 1315.82 Raman unit [R.U.]), followed by the urban (4146.49 ± 535.75 R.U.) and rural (2510.56 ± 611.00 R.U.) sections. Three pollution sources were determined via principal component analysis (i.e., the dominant industrial source, domestic wastewater, and agricultural effluent). Additionally, the results from 2D-COS revealed that sedimentary FA fractions tended to stabilize as the protein-like component was transformed into the HAL component. Furthermore, we used the structural equation model to validate the critical environmental variables affecting the FA fraction transformation. The results can elucidate the influences of human activities on the dynamics of sedimentary FA fractions in urban rivers.

Verifying the applicability of PD/A unit for ultimate sidestream and mainstream polishing: Operating performance, granular characteristics and active microbes

Partial denitrification/anammox (PD/A) has been recently applied to co-treat domestic wastewater and nitrate-containing anammox effluent. However, studies regarding its performance without external organic supplement, spatial characteristics within sludge aggregates, and chronological changes of active microorganisms along PD/A cycle have rarely been reported. Herein, one-stage PD/A unit extremely and simultaneously polished anammox-pretreated reject water (NH4+-N: 65.4 ± 5.7 mg/L, COD: 199.7 ± 23.2 mg/L) and domestic wastewater (NO3−-N: 81.6 ± 7.8 mg/L, TN: 85.8 ± 8.9 mg/L, COD: 338.2 ± 29.0 mg/L) to 4.5 ± 2.1 mg/L without external organic carbon supply. Protective “granules-in-granule” aggregates with densely clustered anammox bacteria embedded in homogeneous denitrifying Thauera prevailed in PD/A system, surviving disadvantages from complex wastewater. Uronic acids and β-sheet proteins in outer extracellular matrix facilitated granulation and pollutants adsorption, while tryptophan- and aromatic-like proteins with tighter secondary structure in inner extracellular matrix maintained granular robustness. Importantly, succession of active microorganisms along the PD/A cycle was revealed by transcript-level analysis for the first time. In PD-period, stimulated Thauera contributed to rapid nitrite accumulation. In subsequent anammox-period, Ca.Brocadia was activated to conduct advanced nitrogen removal, which accompanied the timely nitrate-to-nitrite reduction by Thauera and Ca.Competibacter. Elusimicrobia was active throughout the PD/A cycle, which is conducive to eliminate the dependence of PD process on external carbon source by decomposing complex organics in actual wastewater. Protective granular structure, orderly activation and harmonious cooperation of functional consortia facilitated practical nitrogen removal rate of 0.6 ± 0.1 kg-N/m3/d under anoxic condition, which sheds light on engineering application of anammox technology.

Spinning Submerged Filter Adsorber versus Packed Bed Adsorber for the Continuous Removal of Antibiotics from Wastewater with Activated Carbon

The removal of antibiotics from wastewater is receiving considerable attention to fulfill water quality parameters required for reuse. This study compares a spinning submerged filter adsorber with a fixed bed adsorber for continuous antibiotic removal. Adsorbers were evaluated with micro granular activated carbon (μGAC: 508 μm), coarse powder activated carbon (cPAC: 197 μm), powder activated carbon (PAC: 77 μm), and a domestic wastewater effluent spiked with a mixture of amoxicillin, sulfamethoxazole, and levofloxacin with concentrations ranging from 10 to 50 mg/L. The fixed bed adsorber packed with cPAC was the most efficient adsorber running with wastewater spiked with 50 mg/L of each antibiotic and an empty bed contact time (EBCT) of 4.5 min. The spinning submerged filter adsorber configuration also provided high removal effectiveness using a 15 g/L concentration of PAC but with a lower hydraulic retention time (HRT) of 40 min. This adsorption unit can be filled with small PAC particles, unlike packed beds, and PAC concentrations can be increased up to 150 g/L if necessary. It combines adsorption and filtration with a completely mixed mode of operation in which the PAC concentration can be adapted to effluent micropollutant concentrations, making it an interesting alternative for adsorption processes.

Parametric optimization of additive manufactured biocarrier submerged in sequencing batch reactor for domestic wastewater treatment

The high nutrient concentration in domestic wastewater effluent can endanger the aquatic life via eutrophication. Thus, research have been carried out to prevent harm to aquatic life. In regard biofilm reactors have been successful by far with few limitations. Bio-carrier fabrication of desired shape is one of the limitations. Recently, the invention of additive manufacturing (AM) of object made it feasible to fabricate the desired shape. In this study additive manufactured bio‒carrier (AMB) was printed using AM technique, with high surface area to volume ratio as well as density higher than water. The submerged attach growth sequencing batch biofilm reactor (SAGSBBR) for organic and nutrient removal from domestic wastewater (DWW) was conducted to determine the optimum bio‒carrier filling ratio (FR) and cycle time (CT) by using response surface methodology (RSM) with CT ranging between 12 h and 24 h and FR ranging between 0 and 20%. The maximum chemical oxygen demand (COD), ammonia-nitrogen (NH4+‒N), and total phosphorus (TP) removal was 96.8 mg/L, 93.32 mg/L, and 88.89 mg/L respectively, which was achieved in submerged attached growth sequential biofilm batch reactor with 10% FR (SAGSBBR‒10). The optimization study determined the optimal solution of CT and FR to be 17.07 h and 12.38% respectively, with desirability of 0.987. The predicted mean of responses for the optimal solution were 96.64%, 94.40% and 89.94% for COD removal, NH4+‒N removal and TP removal, respectively. The rate of biomass attachment at the first stage in SAGSBBR‒10 and SAGSBBR‒20 was about 11.39 mg/carrier.d and 8.64 mg/carrier.d, whereas the highest accumulation achieved was 98.27 mg/carrier and 80.15 mg/carrier respectively. Thus, this study can assist us to achieve sustainable development goal (SDG) 6.

Ecosystem Services Valuation of Constructed Wetland as a Nature-Based Solution to Wastewater Treatment

Constructed wetlands (CWs) are nature-based solutions that utilize natural vegetation, soils, and microbes to treat domestic wastewater and industrial effluents. They are engineered treatment systems that mimic the functions of natural wetlands to capture stormwater, reduce nutrient loads, and create diverse wildlife habitats. Providing these monetary and non-monetary benefits, its implementation has grown in several applications and geographical spread. Recent studies integrate the ecosystem services of CWs in project valuation, and the critical analysis of research hotspots has not been made yet. This study employs a systematic review to analyze the literature on ecosystem services provided by CWs and how they are incorporated into the valuation of CW projects. Among the ecosystem services that have been identified are provisioning (biomass and water supply), regulating (wastewater treatment and purification, climate regulation, flood prevention, and erosion control), cultural (recreation and aesthetic, biodiversity, education, and research), and supporting (habitat formation, nutrient cycling, and hydrological cycle). In terms of valuation methods and techniques, the results identified contingent valuation, shadow pricing, cost–benefit analysis, benefits transfer, habitat evaluation procedures, replacement cost, and travel cost. The analysis results provide researchers with a concrete basis for future studies and directions for further development. This also provides policymakers and CW project planners with valuable insights on various aspects of policy support for CW adoption and project valuation.

Utilization of Domestic Wastewater and Textile Effluent Treatment Plant Sludge as Brick Material

Utilization of Domestic Wastewater and Textile Effluent Treatment Plant Sludge as Brick Material

Microplastic contamination in processed and unprocessed sea salts from a developing country and potential risk assessment

In aquatic environments, microplastics (MPs) are pervasive which could have a considerable negative impact on the environment, organisms and pose a risk to human health. However, knowledge about the exposure and ecological risk of MPs in the coastal ecosystems of developing countries is limited. In this study, we analyzed salt samples from five commonly consumed processed and unprocessed sea salts of different commercial brands originated from 15 salt pans in Bangladesh to assess the abundance, characteristics and potential risks of MPs. The quantities of MPs in unprocessed salts (average 195 ± 56 item/kg) were higher than those in the processed salts (average 157 ± 34 item/kg). One-way analysis of variance (ANOVA) showed significant (p < 0.05) differences among the average numbers of MPs in both processed and unprocessed salts. MP levels in this study were 2–3 times higher than those reported from some other countries. Fiber-shaped and transparent MPs were dominant in both cases. MPs less than 0.5 mm in size were the most abundant in both unprocessed (58.2%) and processed (62.2%) salts. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed five types of polymers, including polyethylene terephthalate (PET−35%), polypropylene (PP−27.5%), polyethylene (PE−25%), polystyrene (PS−10%), and Nylon (2.5%) in the studied salts. The sea salts were classified as potential hazard index (PHI) levels IV to V, indicating serious MP contamination, whereas potential ecological risk factor (Ei), potential ecological risk index (RI), and pollutant load index (PLI) indicated moderate levels of pollution of MPs. Domestic and municipal wastewater effluents to Bay of Bengal and fishing activities may attributed to presence of MPs in the sea salt. These findings can be used by consumers, salt industries and policy makers to reduce MPs levels during consumption, production and policymaking.

Freshwater mussels in an impacted watershed: Influences of pollution from point and non-point sources

The Grand River watershed in a densely populated region of Ontario supports one of the richest assemblages of freshwater mussels in Canada. However, water quality in this watershed is influenced by urban development, agriculture, and industry. Mussel populations and water chemistry in the lower Grand River and the Boston Creek tributary were evaluated to determine whether point sources of pollution such as discharges of domestic wastewater and industrial effluent, and non-point sources of pollution are affecting mussel distribution and population structure. Semi-quantitative population surveys conducted at 9 study sites identified 20 mussel species, including 3 Species at Risk. Mussel abundance (34–160 mussels/search hour) and species richness indicated that mussel populations in the lower Grand River watershed are continuing to recover from historical lows reported in the 1970s. However, changes in populations at some sites were consistent with altered water chemistry. Most notable was that the three most abundant mussel species in the Boston Creek tributary downstream of a gypsum plant discharge were significantly smaller in length than those upstream of this site. The water chemistry in this habitat was characterized by elevated conductivity (∼2000 μS/cm) and calcium (∼500 mg/L), as well as concentrations of sulfate (∼1000 mg/L) that can be toxic to freshwater mussels. In the Grand River downstream of the confluence with Boston Creek, there tended to be (p > 0.05) fewer mussels (mean 34 ± 20/search h) compared to upstream (mean 67 ± 15/search h) and this corresponded to altered water chemistry, including elevated sulfate (239 mg/L) downstream of the confluence relative to upstream (58 mg/L). These data indicate that chronic exposures to high levels of major ions is likely driving changes to mussel population structure. In addition, the discharges of wash water from a gypsum plant may be impacting sensitive biota in the main stem Grand River well beyond the immediate tributary receiving environment.

Source apportionment and risk assessment of trace element pollution in Yamuna river water in Delhi: a probability based approach

ABSTRACT This study investigate the sources, seasonal variation, and health risks of ten elements in water collected at ten sites in Yamuna, Delhi. Mean concentration of the elements ranged from 0.8 ± 0.8 µg/L for Co to 9455 ± 6379 µg/L for Fe, and followed in the order Co>Cd >As>Zn>Ni>Cu>Cr>Pb>Mn>Fe. Mean Cr and Pb levels exceed the WHO prescribed limit. Spatial variation was insignificant except for Mn. Seasonal variation of Pb, Cr, Fe, Zn, and As was significant, and in the order summer≥monsoon>winter. Cluster analysis identified five groups of elements. Principal component analysis indicates industrial, agricultural, and domestic wastewater effluents as the chief sources of the observed level of elements. Probability of non-carcinogenic health risk was moderate for Cr (69%), Mn (62%), As (44%), and Fe (29%) and high for Pb (96%). Cr, Ni, Cd, As and Pb pose carcinogenic risk with high probability (84–100%) except for Pb (4.8%).

Comparative Study between Two Substrates of Constructed Wetlands in the Treatment of Domestic Wastewater in Arid Regions

This work aims to conduct a comparative study between two natural substrates (clay and gravel) used in constructed wetlands to treat domestic wastewater effluent in arid regions. Experiments were carried out using four basins planted with phragmites australis, where two were filled with clay and two with gravel substrates. The efficiency of filtration systems has been studied by monitoring several physicochemical and organic parameters. This study is of great importance in determining the most effective type of local substrate in light of the lack of previous studies and the low spread of CWs in arid regions.Results showed that the clay filters clogged very fast, and the total Suspended Solids increased in the planted clay filter by 4 % and decreased in the planted gravel filter, where the removal efficiency was 73%. The pH was generally around neutral, with values between 6.8 and 7.2 regardless of the substrate, and the temperature was related solely to local weather conditions. The electrical conductivity was higher in the effluent from clay than the gravel filters, with 9.72 and 5.47 mS/cm, respectively. The nitrate concentration increased in all filters due to the complete transformation of ammonium to nitrate. After five days, nitrite and chemical oxygen demand removal efficiencies were 38.33%, 75% in the planted clay filter, and 60%, 88% in the planted gravel filter, respectively.

Surface grafting with diverse charged chemical groups mitigates calcium phosphate scaling on reverse osmosis membranes during municipal wastewater desalination

Calcium phosphate scaling on reverse osmosis (RO) membranes during the desalination of municipal wastewater remains a major problem. This study modified RO membranes by graft polymerization using hydrophilic methacrylate monomers to reduce scaling and investigated the effects of surface charge and exposed functional groups on scaling during municipal wastewater desalination. Grafting was performed using negatively charged, neutral, positively charged, and mixed charge monomers. Testing the modified membranes during RO desalination of a solution simulating treated domestic wastewater effluents from the Shafdan wastewater reclamation plant in Israel revealed improved antiscaling performance by grafted membranes compared with the pristine (unmodified) membrane. In particular, membranes grafted using neutral and mixed charge monomers showed the best antiscaling tendencies: 25.6% and 27.6% decrease in flux, respectively, compared with a 59.1% decrease using the pristine membrane. These results, together with physico-chemical characterization, suggested that calcium phosphate precipitation and scaling on the grafted RO membranes are driven mainly by electrostatic and dipole–dipole interactions between charged chemical groups exposed on the membrane surface and ionic species in the test solution; these interactions are minimized in membranes grafted with neutral or mixed charge poly (methacrylate) groups, resulting in enhanced antiscaling performance. This study provides insight into the antiscaling mechanisms of hydrophilic poly (methacrylate) chains grafted on RO membranes, and thus can potentially aid efforts to mitigate calcium phosphate scaling during RO desalination of municipal wastewater. • Diverse charged monomers grafted on RO membrane to mitigate Ca 3 (PO 4 ) 2 scaling. •Grafted membranes exhibit enhanced performance in RO wastewater desalination. •Neutral and mixed-charge grafted polymers show lowest flux decline. •Electrostatic interactions of surface functional groups with ions dominate scaling.

Petrochemical and municipal wastewater treatment plants activated sludge each own distinct core bacteria driven by their specific incoming wastewater

Microorganisms in activated sludge from wastewater treatment plants (WWTPs) form complex networks to convert a wide variety of pollutants, thus ensuring water purification and environmental protection. In this study, activated sludge samples were collected from three full-scale WWTPs: a petrochemical WWTP (PWWTP), a municipal WWTP treating domestic wastewater (MWWTP_D), and a municipal WWTP treating a mixture of domestic wastewater and multiple industrial effluents (MWWTP_I+D). These samples were analyzed by high-throughput sequencing of 16S rRNA gene PCoA and CPCoA indicated that the samples from three WWTPs were separated, suggesting that each WWTP had unique microbiome characters (P < 0.05). This was also evidenced by the different predominant bacteria (PDB), biomarkers, and key nodes of co-occurrence network in the three WWTPs. Microorganisms with all three above mentioned characteristics were defined the core bacteria, specifically: Georgfuchsia, Thauera and GP4 in PWWTP, Phaeodactylibacter and Hyphomicrobiuml in MWWTP_D, and Otheakwangia, Terrimonas, Phenylobacterium, etc. in MWWTP_I + D. Furthermore, in accordance with the functional profile prediction, the functional groups in PWWTP metabolized aromatic compound, sulfur compounds and heavy metal typically present in petrochemical wastewater. In contrast, the microbiome in MWWTP_D was represented by the population breaking down macromolecular biodegradable organic matter and the nitrogen nutrients that constitute the vast majority of domestic wastewater pollutants. Both functional groups coexist in MWWTP_I + D. These results revealed that the specific composition of incoming wastewaters produced distinct ecological niches and modulated the ecological structure of activated sludge microbial communities in real-world WWTPs. However, the generalization of the results of this study will require further research.