The Phromhot Canal is the only natural water source for consumption and agriculture the Sa Kaeo special economic zone, Thailand. At present, the Phromhot Canal is facing a serious problem with water quality. Our study carried out to analyze and assess the pollution carrying capacity of the natural water resource. The sampling sites were examined 7 stations cut across the downstream areas. All these stations were served as the control station to represent the actual condition of the Phromhot Canal. The results indicated that the water quality of the Phromhot Canal after flowing through the Aranyaprathet Municipality's wastewater treatment plant (AM's-WWTP) was severely contaminated. Effluents from the AM's-WWTP does not meet the effluent quality standard of the Ministry of Natural Resources and Environment, Thailand. In addition, it can flow into the water body up to 6,439.55 m3/day. The maximum amount of a pollutant (in terms of BOD loading) allowed to enter a water body of the Phromhot Canal should be ≤ 0.08 kgBOD/day (dry period) and 16.52 kgBOD/day (wet period). While the Phromhot Canal has to carry BOD loading up to 51.12 kgBOD/day. For this reason, the Phromhot Canal at after flowing through the WWTP was unable to the pollution carrying capacity. From the field survey, the AM's-WWTP is not suitable for wastewater treatment, which has a capacity of 923.93 m3/day. Therefore, it is necessary to strictly control the drainage of the wastewater from the Aranyaprathet Municipality's wastewater treatment system, both quantitative and geographic.

Constructed wetland (CWs) systems offer an economical alternative to wastewater (WW) treatment in developing countries. So this study investigated lab-scale hybrid constructed wetlands (HCWs) with plant species Canna indica and Typha latifolia in mono and mixed culture for removing organic matter and nutrients from municipal wastewater (MWW) under arid climatic conditions. A HCW system consists of a storage tank feeding four series of vertical flow constructed wetlands (VFCWs) followed by horizontal flow-constructed wetlands (HFCWs). The results indicate that the planted beds performed better in removing suspended solids (TSS) (89.93% by Typha latifolia), biochemical oxygen demand (BOD5) (95.01% by mixed-culture), chemical oxygen demand (COD) (90.77 by Typha latifolia), nitrite (NO2-) (89.99% by mixed-culture), ammonium nitrogen (NH4+) (99.98 % by mixed-culture), and orthophosphate (PO43-) (87.22% by Typha latifolia) as compared to the unplanted bed for the same parameters (87.85%, 92.87%, 77.35%, 85.30%, 99.75%,  and 80.95%), respectively. The nitrate (NO3−) concentration in the effluent recorded the highest increase in the VFCW unit planted with mixed culture from 0.44 to 0.999 mg/l and decreased in the second stage to 0.588 mg/l at the HCW outlet. The mean values of the testing parameters in different HCW systems were not significant between the mono and mixed culture (P > 0.05), with a significant difference (P <0.05) between the VFCWs and HFCWs. The finding of this study demonstrated that Canna indica and Typha latifolia have been effective in WW treatment by HCW systems.

In the coming years, the use of microalgal biomass as agricultural biofertilizers has shown promising results. The use of wastewater as culture medium has resulted in the reduction of production costs, making microalgae-based fertilizers highly attractive for farmers. However, the occurrence of specific pollutants in wastewater, like pathogens, heavy metals and contaminants of emerging concern (CECs), such as pharmaceuticals and personal care products may pose a risk on human health. This study presents an holistic assessment of the production and use of microalgal biomass grown in municipal wastewater as biofertilizer in agriculture. Results showed that pathogens and heavy metals concentrations in the microalgal biomass were below the threshold established by the European regulation for fertilizing products, except for cadmium. Regarding CECs, 25 out of 29 compounds were found in wastewater. However, only three of them (hydrocinnamic acid, caffeine, and bisphenol A) were found in the microalgae biomass used as biofertilizer. Agronomic tests were performed for lettuce growth in greenhouse. Four treatments were studied, comparing the use of microalgae biofertilizer with a conventional mineral fertilizer, and also a combination of both of them. Results suggested that microalgae can help reducing the mineral nitrogen dose, since similar fresh shoot weights were obtained in the plants grown with the different assessed fertilizers. Lettuce samples revealed the presence of cadmium and CECs in all the treatments including both negative and positive controls, which suggests that their presence was not linked to the microalgae biomass. On the whole, this study revealed that wastewater grown microalgae can be used for agricultural purposes reducing mineral N need and guaranteeing health safety of the crops. | This research was supported by the European Commission (FERTILWASTES-EFA307/19) and the Spanish Ministry of Science and Innovation (CYRCLE-PID2020-113866RA-I00). E. Uggetti and R. Díez- Montero would like to thank the Spanish Ministry of Industry and Economy for their research grants [RYC2018-025514-I and ICJ2019- 042069-I, respectively]. A. Álvarez-González kindly acknowledge the Departament de Recerca i Universitats de la Generalitat de Catalunya for her PhD scholarship (FI AGAUR, 2022FI_B 00488). E. Gonzalez-Flo would like to thank the European Union-NextGenerationEU, Ministryof Universities and Recovery, Transformation and Resilience Plan for her research grant (2021UPF-MS-12). M. Escolà Casas wants to thank the Beatriu de Pinós 2018 grant-programme (MSCA grant agreement number 801370) for the funding.

In this study, the occurrence of pharmaceuticals, hormones and bacterial community structures was studied at a wastewater treatment plant in Finland having two different parallel treatment lines: conventional activated sludge (CAS) treatment with a sedimentation stage, and a membrane bioreactor (MBR). Influent and effluents were sampled seven times over a period of one year. The bacterial communities of the influent samples showed a high degree of similarity, except for the February sample which had substantially lower diversity. There was significant fluctuation in the species richness and diversity of the effluent samples, although both effluents showed a similar trend. A marked decrease in diversity was observed in effluents collected between August and November. The initiation of nitrogen removal as a result of an increase in temperature could explain the changes in microbial community structures. In overall terms, suspended solids, bacteria and total organic matter (COD and BOD) were removed to a greater extent using the MBR, while higher Tot-N, Tot-P and nitrate removal rates were achieved using the CAS treatment. Estrone (E1) concentrations were also consistently at a lower level in the MBR effluents (<0.1–0.68 ng/l) compared to the CAS effluents (1.1–12 ng/l). Due to the high variation in the concentrations of pharmaceuticals, no clear superiority of either process could be demonstrated with certainty. The study highlights the importance of long-term sampling campaigns to detect variations effectively.

Dichlorophenol (DCP), a commonly used fungicide and insecticide, is widely found in waters and wastewaters. Herein, the degradation of DCP by Ferrate (Fe(VI)) in different matrices was comprehensively investigated. In pure water, a complete removal of DCP was achieved in 300 s at [Fe(VI)]:[DCP] molar ratio of 2:1. The presence of HA (10 mg L⁻¹) inhibited DCP degradation to a certain extent. A total of twenty degradation products were identified by HPLC/MS analysis. Based on these products, reaction pathways including the cleavage of C–C bridge bond, hydroxylation, and radical coupling were proposed. These reaction mechanisms were further rationalized by theoretical calculations. The analyses of Wiberg bond orders and transition state indicated that C₇–C₈ bond was the most vulnerable site for cleavage, and C₁₂ site was the most likely site for hydroxyl addition. Mulliken atomic spin densities distribution suggested that self-coupling products was easily generated via C–O–C coupling ways. Finally, the feasibility of applying Fe(VI) to degrade DCP (20 μM) in a municipal wastewater effluent and a lake water was evaluated and verified. The findings in this study are of relevance in designing Fe(VI)-based treatment strategy for chlorine-containing persistent pesticides.

The beta-blocker atenolol (ATE), and the selective serotonin and norepinephrine reuptake inhibitor, venlafaxine (VEN) are frequently detected in municipal wastewater effluents, but little is known about their ecotoxicological effect on aquatic animals. Herein, ATE and VEN were selected to explore their accumulation and global DNA methylation (GDM) in zebrafish tissues after a 30-day exposure. Molecular dynamics (MD) stimulation was used to investigate the toxic mechanism of ATE and VEN exposure. The results demonstrated that ATE and VEN could reduce the condition factor of zebrafish. The bioaccumulation capacity for ATE and VEN was in the order of liver > gut > gill > brain and liver > gut > brain > gill, respectively. After a 30-day recovery, ATE and VEN could still be detected in zebrafish tissues when exposure concentrations were ≥10 μg/L. Moreover, ATE and VEN induced global DNA hypomethylation in different tissues with a dose-dependent manner and their main target tissues were liver and brain. When the exposure concentrations of ATE and VEN were increased to 100 μg/L, the global DNA hypomethylation of liver and brain were reduced to 27% and 18%, respectively. In the same tissue exposed to the same concentration, DNA hypomethylation induced by VEN was more serious than that of ATE. After a 30-day recovery, the global DNA hypomethylations caused by the two drugs were still persistent, and the recovery of VEN was slower than that of ATE. The MD simulation results showed that both ATE and VEN could reduce the catalytic activity of DNA Methyltransferase 1 (DNMT1), while the effect of VEN on the 3D conformational changes of the DNMT1 domain was more significant, resulting in a lower DNA methylation rate. The current study shed new light on the toxic mechanism and potential adverse impacts of ATE and VEN on zebrafish, providing essential information to the further ecotoxicological risk assessment of these drugs in the aquatic environment.

Hypoxia (low oxygen) often occurs in aquatic ecosystems that receive effluent from municipal wastewater treatment plants (WWTP). The combination of hypoxia and WWTP effluent could impair fish health, because WWTP effluent contains multiple contaminants that could disrupt the physiological pathways fish use to cope with hypoxia, but the interactive effects of these stressors on fish physiology are poorly understood. We have examined this issue by exposing mummichog killifish (Fundulus heteroclitus) to hypoxia (5 and 2 kPa O₂) and/or 100% WWTP effluent for 21 days in a full factorial design. We then measured hypoxia tolerance, whole-animal metabolism, gill morphology, haematology, and tissue metabolites. In clean water, killifish responded to chronic hypoxia with improvements in hypoxia tolerance, as reflected by increases in time to loss of equilibrium at 0.5 kPa (tLOE). These improvements occurred in association with increases in the exposed surface of gill lamellae that resulted from a regression of interlamellar cell mass (ILCM). Concurrent exposure to wastewater attenuated the increases in tLOE and gill remodeling in chronic hypoxia, and nearly depleted brain glycogen stores. Therefore, exposure to WWTP effluent can disrupt the physiological mechanisms fish use to cope with chronic hypoxia and impair hypoxia tolerance. Our research suggests that the combination of stressors near WWTPs can have interactive effects on the physiology and health of fish.

One of the strategies to realize a nitrogen cycle society, we attempted to recover ammonium ions from industrial wastewater, especially sewage water with adsorbent materials. We have developed an adsorbent with high ammonium selectivity based on copper hexacyanoferrate and granulated it as pellets. Using a compact column system filled with this granule adsorbent, ammonium ions were recovered from sewage containing 1000–1500 mg-NH₄⁺/L ammonium ions. Despite the coexistence of many metal ions, the adsorbent selectively and stably adsorbed ammonium ions. Furthermore, it was shown that the saturated adsorbent can be regenerated by flowing a potassium ion solution through a column adsorbent to desorb ammonium ions. In other words, the column can be used repeatedly, and there was almost little deterioration in adsorption even after 250 cycles. In addition, it was shown that by increasing the number of stages of this column, it is possible to sufficiently reduce the ammonium in the adsorbent solution and recover the concentrated ammonium solution.

Horizontal gene transfer (HGT) plays an important role in the dissemination of antibiotic resistance genes. In sewer systems, human-associated and environmental bacteria are mixed together and exposed to many substances known to increase HGT, including various antibacterial compounds. In wastewaters, those substances are most often detected below concentrations known to induce HGT individually. Still, it is possible that such wastewaters induce HGT, for example via mixture effects. Here, a panel of antibiotics, biocides and other pharmaceuticals was measured in filter-sterilized municipal and hospital wastewater samples from Gothenburg, Sweden. The effects on HGT of the chemical mixtures in these samples were investigated by exposing a complex bacterial donor community together with a GFP-tagged E. coli recipient strain. Recipients that captured sulfonamide resistance-conferring mobile genetic elements (MGEs) from the bacterial community were enumerated and characterized by replicon typing, antibiotic susceptibility testing and long read sequencing. While exposure to municipal wastewater did not result in any detectable change in HGT rates, exposure to hospital wastewater was associated with an increase in the proportion of recipients that acquired sulfonamide resistance but also a drastic decrease in the total number of recipients. Although, concentrations were generally higher in hospital than municipal wastewater, none of the measured substances could individually explain the observed effects of hospital wastewater. The great majority of the MGEs captured were IncN plasmids, and resistance to several antibiotics was co-transferred in most cases. Taken together, the data show no evidence that chemicals present in the studied municipal wastewater induce HGT. Still, the increased relative abundance of transconjugants after exposure to hospital wastewater could have implications for the risks of both emergence and transmission of resistant bacteria.

In this study, a multidisciplinary approach investigated the enzymatic degradation of micropollutants in real, not modified, municipal wastewaters of a plant located in Italy. Stir Bar Sorptive Extraction combined to Gas Chromatography-Mass Spectrometric detection (SBSE-GC-MS) was applied to profile targeted pollutants in wastewaters collected after the primary sedimentation (W1) and the final effluent (W2). Fifteen compounds were detected at ng/L - μg/L, including pesticides, personal care products (PCPs) and drugs. The most abundant micropollutants were bis(2-ethylhexyl) phthalate, diethyl phthalate and ketoprofen. Laccases of Trametes pubescens MUT 2400 were very active against all the target micropollutants: except few cases, their concentration was reduced more than 60%. Chemical analysis and environmental risk do not always come together. To verify whether the treated wastewaters can represent a stressor for the aquatic ecosystem, toxicity was also evaluated. Raphidocelis subcapitata and Lepidium sativum tests showed a clear ecotoxicity reduction, even though they did not evenly respond. Two in vitro tests (E-screen test and MELN assay) were used to evaluate the estrogenic activity. Treatments already operating in the plant (e.g. activated sludge) partially reduced the estradiol equivalent concentration, and it was almost negligible after the laccases treatment. The results of this study suggest that laccases of T. pubescens are promising biocatalysts for the micropollutants transformation in wastewaters and surface waters.