Large amounts of wastewater discharge have emerged as a burden in the process of industrialization and urbanization. In this study, a dynamic wastewater-induced input-output model is developed to systematically analyze the related situation. The developed model is applied to Guangdong Province, China to analyze its prominent characteristics from 2002 to 2015. Combining input-output analysis, ecological network analysis and structural decomposition analysis, the developed model reveals issues of direct and indirect discharges, relationships among various discharges, and driving forces of wastewater discharges. It is uncovered that Primary Manufacturing and Advanced Manufacturing dominate the system because of significant temporal and spatial variations in wastewater discharge. In addition, Manufacturing of paper, computer and machinery and Services are the key industries responsible for large amounts of wastewater discharge and unhealthy source-discharge relationships. The largest wastewater discharge occurred in 2005 and indirect wastewater discharge is the main form. Furthermore, final demand is found to be the biggest driving force of wastewater discharge. Finally, a three-phase policy implementation system implemented in stages proposes solutions to wastewater problems.

Industrial dye effluents, which are a major wastage component that enter the natural environment, pose a significant health risk to human and aquatic life. Therefore, the effective removal of dye effluents is a major concern. Against this backdrop, in this study, a low-cost, earth-abundant, and ecofriendly ɤ-Fe₂O₃–PPy nanocomposite was prepared employing the conventional hydrothermal method. The morphology, functional groups, and elemental composition of ɤ-Fe₂O₃–PPy were characterized by XRD, SEM, XPS, and FTIR studies. Under optimized conditions, the prepared novel ɤ-Fe₂O₃–PPy nanocomposite showed a high methylene blue (MB) adsorption capacity of 464 mg/g, which is significantly higher than that of existing adsorbents such as CNTs and polymer-modified CNTs. The adsorption parameters such as pH, adsorbent dosage, and ionic strength were optimized to enhance the MB adsorption capacity. The adsorption results revealed that MB is adsorbed onto the adsorbent surface via electrostatic interactions, hydrogen bonding, and chemical binding interactions. In terms of practical application, the adsorbent’s adsorption–desorption ability in conjunction with magnetic separation was investigated; the prepared ɤ-Fe₂O₃–PPy nanocomposite exhibited excellent adsorption and desorption efficiencies over more than seven adsorption–desorption cycles.

The soybean processing wastewater (SPW) supplementation to facilitate the simultaneously treatment (SPW and mesosulfuron-methyl) of wastewater and production of biological substances by Rhodopseudomonas sphaeroides (R. sphaeroides) was discussed. Compared with the control group, with the addition of SPW, mesosulfuron-methyl was removed, and the yields of single-cell proteins, carotenoids, and bacteriochlorophyll were increased. In the 3 mg/L dose group, the mesosulfuron-methyl removal rate reached 97% after 5 days. Molecular analysis revealed that mesosulfuron-methyl exhibited induction effects on expression of the cpm gene and regulation effects on the synthesis of cytochrome P450 monooxygenases (P450) by activating HKs gene in TCS signal transduction pathway. For R. sphaeroides, this induction process required 1 day. The synthesis of P450 occurred 1 day after inoculation. Prior to expressing cpm gene and synthesizing P450, R. sphaeroides need a period of time to adapt to external mesosulfuron-methyl stimulation. However, the R. sphaeroides growth could not be maintained for more than 1 day due to the lack of organic matter in the raw wastewater. The SPW supplementation provided a sufficient carbon source in four groups with added SPW. After 5 days, R. sphaeroides became the dominant microflora in the wastewater. This new method could complete the treatment of mixed wastewater, the increased of biological substances output and the reuse of wastewater and R. sphaeroides cells as resources at the same time.

The performance of the cathode significantly affects the ability of the electro-Fenton (EF) process to degrade chemicals. In this study, a simple method to modify the graphite felt (GF) cathode was proposed, i.e. oxidizing GF by hydrothermal treatment in nitric acid. The surface physical and electrochemical properties of modified graphite felt were characterized by several techniques: scanning electron microscope (SEM), water contact angle, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and linear scanning voltammetry (LSV). Compared with an unmodified GF (GF-0), the oxygen reduction reaction (ORR) activity of a modified GF was significantly improved due to the introduction of more oxygen-containing functional groups (OGs). Furthermore, the results showed that GF was optimally modified after 9 h (GF-9) of treatment. As an example, the H₂O₂ generation by GF-9 was 2.26 times higher than that of GF-0. After optimizing the process parameters, which include the initial Fe²⁺ concentration and current density, the apparent degradation rate constant of levofloxacin (LEV) could reach as high as 0.40 min⁻¹. Moreover, the total organic carbon (TOC) removal rate and mineralization current efficiency (MCE) of the modified cathode were much higher than that of the GF-0. Conclusively, GF-9 is a promising cathode for the future development in organic pollutant removal via EF.

Wastewater containing high concentrations of nitriles, if discharged without an appropriate nonhazardous disposal strategy, will cause serious environmental pollution. During secondary sewage biological treatment, most existing bacteria cannot endure high-concentration nitriles due to poor tolerance and low degradation ability. The Rhodococcus rhodochrous strain BX2 screened by our laboratory shows high resistance to nitriles and can efficiently degrade these compounds. Compared with sole high-concentration nitriles present in the biodegradation process, the addition of glucose at a suitable concentration can effectively increase the biomass of BX2, promote the expression of nitrile-degrading enzyme genes, improve the activities of these enzymes and enhance the pollutant removal efficiency via carbon catabolite repression (CCR) mechanisms. Whole-genome sequencing revealed that the four key regulators of CCR identified in gram-negative and gram-positive bacteria are concomitant in BX2. This study provides an economically feasible strategy for the microbial remediation of high-concentration nitriles and other organic pollutants.

Struvite (MgNH₄PO₃·6H₂O) crystallization is one of important methods of phosphorus recovery from wastewater. As to livestock wastewater, the high-strength occurrence of antibiotics and antibiotic resistance genes might induce struvite recovery to spread antibiotic resistance to the environment. However, limited information has been reported on the simultaneous transport of antibiotics and ARGs in struvite recovery. In the present study, tetracyclines (TCs) and tetracyclines antibiotic resistance genes (ARGs) were selected as the targeted pollutants, and their discrepant residues in struvite recovery from swine wastewater were investigated. TCs and ARGs were obviously detected, with their contents of 4.88–79.5 mg/kg and 6.99 × 10⁷–2.14 × 10¹¹ copies/g, notably higher than those of TCs 0.550–1.94 mg/kg and ARGs 3.98 × 10⁴–5.66 × 10⁷ copies/g obtained from synthetic wastewater. The correlational relationship revealed that predominant factors affecting TCs and ARGs transports were different. Results from network analyses indicated that among the total edges, the negative correlations between TCs and ARGs predominately occupied 18.0%. The redundancy analysis revealed that mineral components in the recovered products, including struvite, K-struvite and amorphous calcium phosphate, coupling with organic contents, displayed insignificant roles on TCs residues, where heavy metals exerted positive and remarkable functions to boost TCs migration. Unexpectedly, mineral components and heavy metals did not displayed significant promotion on ARGs transport as a whole.

Recent reports are pointing towards the potential increasing risks of resistomes in human host. With no permissible limit in sight, resistomes are continually multiplying at an alarming rate in the ecosystem, with a disturbing level in drinking water source. The morphology and chemical constituent of resistomes afford them to resist degradation, elude membrane and counter ionic charge, thereby, rendering both conventional and advanced water and wastewater treatment inefficient. Water and wastewater matrix may govern the propagation of individual resistomes sub-type, co-selection and specific interaction towards precise condition may have enhanced the current challenge. This review covers recent reports (2011–2019) on the occurrence of ARB/ARGs and ease of spread of resistance genes in the aquatic ecosystem. The contributions of water matrix to the spread and mitigation, treatment options, via bulk removal or capture, and intracellular and extracellular DNA lysis were discussed. A complete summary of recent occurrences of ARB/ARGs, fate after disinfection and optimum conditions of individual treatment technology or in tandem, including process limitations, with a brief assessment of removal or degradation mechanism were highlighted.

The extensive use of melamine and its three derivatives (i.e., ammeline, ammelide, and cyanuric acid) resulted in their widespread occurrence in the environment. Nevertheless, limited information is available on their distribution in the aquatic environment. In this study, concentrations and profiles of melamine and its derivatives were determined in 223 water samples, comprising river water, lake water, seawater, tap water, bottled water, rain water, wastewater, and swimming pool water, collected from New York State, USA. The sum concentrations of melamine and its derivatives (∑₄MELs) decreased in the following order: swimming pool water (median: 1.5 × 10⁷ ng/L) ≫ wastewater (1240) > precipitation (739) > tap water (512) > river water (370) > lake water (347) > seawater (186) > bottled water (98). Cyanuric acid was the major compound, accounting for 60–100% of ∑₄MELs concentrations in swimming pool water, wastewater, precipitation, tap water, seawater, and bottled water, whereas melamine dominated in river and lake water (54–64% of ∑₄MELs). Significant positive correlations (0.499 < R < 0.703, p < 0.002) were found between the concentrations of melamine and atrazine (a triazine herbicide) in surface waters. The geographic distribution in the concentrations of ∑₄MELs in river, lake, and tap water corresponded with the degree of urbanization, suggesting that human activities contribute to the sources melamine and cyanuric acid in the aquatic environments. A preliminary hazard assessment of melamine and cyanuric acid in waters suggested that their ecological or human health risks were minimal. This is the first study to document the occurrence and spatial distribution of melamine and its derivatives in waters from the United States.

While considerable efforts have been made to address the relationship between urbanization and environmental issues, few of them focus on household emissions. Thus, this work aimed at evaluating the effect of urbanization on household wastewater emissions, and made a distinction between the efficient- and the inefficient-emissions. We compiled a China’s provincial dataset over the period 2005–2017, and estimates indicated that a 1% rise in the urbanization was correlated with a 0.581 increase of efficient emissions, while inefficient emissions decreased by 7.606. As of 2017, the sample period end year, the inefficient emissions accounted for 10.5% of the total emissions of China as a whole, which was relatively large and could not be overlooked. Meanwhile, a back-of-the-envelope estimate revealed that urbanization had a negative impact on China’s total emissions, with a marginal effect ranging from −0.226 to −1.354 over the sample period. The above findings, however, did not imply that urbanization would spontaneously reduce the inefficient- and total-emissions. Thus, the government in the process of urbanization should strengthen environmental education, municipal facilities, and others.

The occurrence of Active Pharmaceutical Ingredients (APIs) in the environment is becoming a major area of concern due to their undesirable effects on non-target organisms. This study investigated the occurrence and risk of contamination by five antibiotics and three antiretrovirals drugs in a fast-growing peri-urban area in Kenya, with inadequate sewer system coverage. Due to poor sewage connectivity and poorly designed decentralized systems, wastewater is directly released in open drains. Water and sediment samples were collected from open surface water drains, while wastewater samples were collected from centralized wastewater treatment plants (WWTP). Solid-phase extraction and ultrasonic-assisted extraction for the aqueous and sediment samples respectively were carried out and extracts analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) using isotopically labeled internal standards. APIs were observed with the detection frequency ranging from 36% to 100%. High mean concentrations of 48.7 μg L⁻¹, 108 μg L⁻¹, and 532 μg L⁻¹ were observed in surface drains for Lamivudine (3 TC), Sulfamethoxazole (SMX), Ciprofloxacin (CIP) respectively. Drain sediments also showed high concentrations of APIs ranging from 2.1 to 13,100 μg kg⁻¹. APIs in this study exceeded those observed in existing literature studies. JKUAT WWTP removal efficiencies varied from −90.68% to 72.67%. Total APIs emission load of the study area was 3550 mg d⁻¹ with WWTP effluent contributing higher loads (2620 mg d⁻¹) than surface water drains (640 mg d⁻¹). Zidovudine (ZDV), nevirapine (NVP), and trimethoprim (TMP) loads in drains, however, exceeded WWTP effluent. Low to high ecotoxicity risk of the individual APIs were observed to the aquatic environment, with high risks for the development of antibiotic resistance in microbiome as determined by the risk quotient (RQ) approach. Risk management through efficient wastewater collection, conveyance, and treatment is necessary to suppress the measured concentrations.