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Due to water scarcity challenges around the world, it is essential to think about non-conventional water resources to address the increased demand in clean freshwater. Environmental and public health problems may result from insufficient provision of sanitation and wastewater disposal facilities. Because of this, wastewater treatment and recycling methods will be vital to provide sufficient freshwater in the coming decades, since water resources are limited and more than 70% of water are consumed for irrigation purposes. Therefore, the application of treated wastewater for agricultural irrigation has much potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for plant production. Among the current treatment technologies applied in urban wastewater reuse for irrigation, wetlands were concluded to be the one of the most suitable ones in terms of pollutant removal and have advantages due to both low maintenance costs and required energy. Wetland behavior and efficiency concerning wastewater treatment is mainly linked to macrophyte composition, substrate, hydrology, surface loading rate, influent feeding mode, microorganism availability, and temperature. Constructed wetlands are very effective in removing organics and suspended solids, whereas the removal of nitrogen is relatively low, but could be improved by using a combination of various types of constructed wetlands meeting the irrigation reuse standards. The removal of phosphorus is usually low, unless special media with high sorption capacity are used. Pathogen removal from wetland effluent to meet irrigation reuse standards is a challenge unless supplementary lagoons or hybrid wetland systems are used.

Microalgal biomass may have biostimulating effects on plants and seeds due to its phytohormonal content, and harnessing this biostimulating effect could contribute to sustainable agriculture. Two Nordic strains of freshwater microalgae species Chlorella vulgaris and Scenedesmus obliquus were each cultivated in a photobioreactor receiving untreated municipal wastewater. The algal biomass and the supernatant after algal cultivation were tested on tomato and barley seeds for biostimulating effects. Intact algal cells, broken cells, or harvest supernatant were applied to the seeds, and germination time, percentage and germination index were evaluated. Seeds treated with C. vulgaris , in particular intact cells or supernatant, had up to 25 percentage units higher germination percentage after 2 days and an overall significantly faster germination time (germinated on average between 0.5 and 1 day sooner) than seeds treated with S. obliquus or the control (water). The germination index was higher in C. vulgaris treatments than in the control for both tomato and barley, and this was observed for both broken and intact cells as well as supernatant. The Nordic strain of C. vulgaris cultivated in municipal wastewater thus shows potential for use as biostimulant in agriculture, adding novel economic and sustainability benefits.

Textile dyes are frequently disposable in aqueous effluents, making it difficult to remove them from industrial effluents before their release to natural waters. This paper deals with the fabrication of cellulose-based adsorbents by reacting nanocelulose crystalline (nanocel) with N -[3-(trimethoxysilyl)propyl]ethylenediamine (TMSPEDA), forming the hybrid (silylpropyl)ethylenediamine@nanocellulose (SPEDA@nanocel), which was employed as adsorbent for the uptake of reactive yellow 2 dye (RY-2) from aqueous effluents. Characterisation of SPEDA@nanocel was carried out using FTIR, SEM–EDS, XRD, TGA, surface area, pH pzc , and hydrophobicity/hydrophilicity ratio (HI). Also, adsorption studies were thoroughly investigated. The effect of initial pH indicated that the maximum uptake of RY-2 takes place at pH 2, which is an indication of the electrostatic mechanism. The kinetic data carried out with 250 and 500 mg L −1 RY-2 with SPEDA@nanocel followed better the nonlinear fractional-like pseudo-first-order model. The t 0.5 and t 0.95 for the dye uptake were about 30 and 141 min, respectively. The equilibrium data from 10 to 45 °C indicated that the Liu isotherm model was the best-fitted isothermal model. The maximum sorption capacity attained was 112.3 mg g −1 at 45 °C. The thermodynamic data have shown that the equilibrium was favorable and endothermic, and the ΔH° was compatible with an electrostatic attraction between RY-2 and SPEDA@nanocel. Experiments of desorption of loaded adsorbent showed promising results for real applications since at least 5 adsorption/desorption cycles could be employed without significant changes in the recovery and with high precision.

Paracetamol, a common pain reliever, has seen a significant rise in use, particularly during the Coronavirus Disease 2019 (COVID-19) pandemic. This widespread consumption has led to increased levels of paracetamol in the environment through wastewater discharge. This raises concerns about its potential impact on aquatic ecosystems. Here, we review the state-of-the-art methods for removing paracetamol from wastewater, focusing on adsorption techniques. We explore how different materials and operational conditions influence the effectiveness of this approach. We also discuss the potential of combining adsorption with oxidative methods for enhanced removal. We further assess the environmental impact by critically examining the ecotoxicological effects of paracetamol on aquatic organisms. This analysis compares established toxicity values with those observed in studies using real wastewater samples. Finally, we highlight the specific needs for further research and development of efficient and sustainable strategies to mitigate paracetamol pollution, ensuring the safety of both human and aquatic life.

This study aimed to quantify the impact of sponge city facilities on both runoff reduction and carbon emission mitigation, providing valuable insights for sustainable urban development. Using the Storm Water Management Model (SWMM) 5.2 in conjunction with carbon emission factor calculations, we comparatively evaluated the annual runoff reduction and carbon emission abatement potential of traditional drainage systems versus those incorporating sponge city facilities. Our results showed that the implementation of sponge city facilities resulted in a substantial decrease in runoff volume (100,840 m3), and a corresponding reduction in carbon emissions (7,089.85 kg CO2 eq) compared to the pre-renovation conditions. Additionally, this work assessed five sponge city facilities: green roofs, permeable pavements, sunken green spaces, rain gardens, and overflow storage ponds. Among these, overflow storage ponds demonstrated the highest efficiency in both runoff reduction (35,879 m3) and carbon emission mitigation (2,522.57 kg CO2 eq). Rain gardens showed the second-best performance, while sunken green spaces had the least impact. Our study provides a novel technical framework for quantifying and evaluating carbon emissions in urban drainage systems. Our findings offer reliable data support for urban planners and policymakers, contributing to evidence-based decision-making in the design and implementation of sponge city projects.

Nanoplastics, commonly used in cosmetics, enter wastewater systems and interact with activated sludge, yet their effects on microorganisms, essential for wastewater treatment, remain poorly understood. The aim of this study was to investigate the effects of polyacrylic acid-based nanoplastics (PANPs) on microorganisms in activated sludge. The PANPs were characterized in terms of their material composition, size, zeta potential, and additive content. Acute (30 min) and prolonged (up to 6 h) toxicity tests were performed to evaluate negative effects on heterotrophic and nitrifying microorganisms in activated sludge. In addition, ready and inherent biodegradability tests were performed to assess their degradation in the environment and within wastewater treatment plants, respectively. The results showed a significant acute inhibition of heterotrophic and nitrifying activity (up to 55 and 72%, respectively) at the highest concentration tested (100 mg/L, 30 min), primarily attributed to the presence of 1-dodecanol detected in the PANPs. This effect decreased with prolonged exposure, likely due to the volatilization of 1-dodecanol. Nevertheless, the PANPs were found to be non-biodegradable in both the ready and inherent biodegradability tests. Although PANPs do not appear to pose a long-term threat to the activated sludge, their persistence in the environment raises concerns about possible accumulation.

The rapid development in agriculture and industrial sectors has raised some serious global issues like heavy metals pollution of water resources. Cadmium (Cd) is amongst the major water pollutants worldwide. In this study, two novel sorbents were prepared by using post-consumer textile waste (PCTW). The waste denim fabric was recycled with environmentally friendly H 2 O 2 and Ozone through oxidation under alkaline conditions to produce several functional groups at the surface (named as ODF@H 2 0 2 and ODF@0 3 respectively) that could trap the heavy metal cations from contaminated water. The functionalized fabric sorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-Ray (EDX) that revealed the presence of carboxylic acid, hydroxyl, and amine functional groups on their surfaces. The sorption isotherm, sorption kinetics and sorption thermodynamics were carried out to unravel the sorption process mechanism. The ODF@H 2 0 2 sorbent was proved more effective by giving maximum adsorption capacity of (238.09 mg g −1 ) compared to Ozone treatment (175.44 mg g −1 ) for Cd 2+ and achieved within just 20 min for both sorbents. Pseudo 2nd order and Langmuir models confirmed the chemosorption as dominant mechanism for the monolayer sorption of Cd 2+ ions onto ODF@H202 and ODF@0 3 . The sorption thermodynamic revealed the sorption process as endothermic and spontaneous in nature. The results showed that both ODF@H 2 0 2 and ODF@0 3 sorbents have an efficient potential for sorbing Cd from contaminated water. Furthermore, both ODF@H 2 0 2 and ODF@0 3 sorbents were also tested in a regeneration study to investigate the reuse of these sorbents, and we achieved marvelous results. Both sorbents gave up to 90% of the sorption capacity even after 10 recycles. Conclusively, both sorbents can have their implications for the preparation of filters that can be used for the treatment of wastewater. This study has practical significance by tackling the two environmental problems i.e. heavy metal pollution and denim waste.

Azo dyes are recalcitrant organic pollutants present in textile industry effluents. Conventional treatment methods to remove them come with a range of disadvantages. Nanoparticles and their nanocomposites offer more efficient, less expensive and easy to handle wastewater treatment alternative. In this study, nanoparticles of nickel oxide (NiO-NPs), copper oxide (CuO-NPs) and their nanocomposite (NiO/CuO-NC) were synthesized using co-precipitation method. The functional groups present on the surface of synthesized nanomaterials were verified using Fourier-transform infrared spectroscopy (FTIR). Surface morphology was assessed using scanning electron microscopy (SEM) whereas purity, shape and size of the crystallite were determined using X-ray diffraction (XRD) technique. The potential of these nanomaterials to degrade three dyes i.e., Reactive Red-2 (RR-2), Reactive Black-5 (RB-5) and Orange II sodium salt (OII) azo dyes, was determined in an aqueous medium under visible light (photocatalysis). The photodegradation effectiveness of all nanomaterials was evaluated under different factors like nanomaterial dose (0.02-0.1 g 10 mL ), concentration of dyes (20-100 mg L ), and irradiation time (60-120 min). They were also assessed for their potential to adsorb RR-2 and OII dyes. Results revealed that at optimum concentration (60 mgL ) of RR-2, RB-5, and OII dyes, NiO-NPs degraded 90, 82 and 83%, CuO-NPs degraded 49, 34, and 44%, whereas the nanocomposite NiO/CuO-NC degraded 92, 93, and 96% of the said dyes respectively. The nanomaterials were categorized as the efficient degraders of the dyes in the order: NiO/CuO-NC > NiO-NPs > CuO-NPs. The highest degradation potential shown by the nanocomposite was attributed to its large surface area, small particles size, and quick reactions which were proved by advance analytical techniques. The equilibrium and kinetic adsorption of RR-2 and OII on NiO-NPs, CuO-NPs, and NiO/CuO-NC were well explained with Langmuir and Pseudo second order model, respectively (R ≥ 0.96). The maximum RR-2 adsorption (103 mg/g) was obtained with NiO/CuO-NC. It is concluded that nanocomposites are more efficient and promising for the dyes degradation from industrial wastewater as compared with dyes adsorption onto individual NPs. Thus, the nanocomposite NiO/CuO-NC can be an excellent candidate for photodegradation as well as the adsorption of the dyes in aqueous media.

To meet future nitrogen removal targets, Henriksdal wastewater treatment plant (WWTP) will require external carbon addition, estimated at 8 tons COD/day by 2040, due to low influent BOD/TN ratios, precipitation chemical use, and low temperatures. Methanol, the projected option, is fossil-based and contributes to indirect greenhouse gas emissions. This study evaluated a volatile fatty acid (VFA)-based fermentate produced from primary sludge and food waste in a 2 m3 mesophilic fermenter as a carbon source for denitrification. The filtrated fermentate was tested as carbon source in both batch denitrification tests and pilot-scale MBR (4.5 m3/h), where it was dosed for 70 days, replacing glycerol currently used at Henriksdal and Henriksdals WWTP. In batch tests, the fermentate achieved a 40% higher denitrification rate than glycerol. Pilot trials showed a 30% higher denitrification rate and 50% lower carbon consumption while maintaining effluent concentration below 3 mg NO3- -N/L. Microbial analysis revealed no significant community changes with the carbon source transition, indicating effective VFA uptake by existing microorganisms. Full-scale projections suggested that replacing methanol would require 10% of the plant's primary sludge plus food waste. Although this sludge use would reduce biogas production, methane potential tests showed that recycling of the fermentate solid fraction would result in only 2% lower biogas production, representing a minor trade-off.

The rampant use of plastics, with the potential to degrade into insidious microplastics (MPs), poses a significant threat by contaminating aquatic environments. In the present study, we delved into the analysis of effluents from textile industries, a recognized major source of MPs contamination. Data were further discussed and compared with a municipal wastewater treatment plant (WWTP) effluent. All effluent samples were collected at the final stage of treatment in their respective WWTP. Laser diffraction spectroscopy was used to evaluate MP dimensions, while optical and fluorescence microscopies were used for morphology analysis and the identification of predominant plastic types, respectively. Electrophoresis was employed to unravel the prevalence of negative surface charge on these plastic microparticles. The analysis revealed that polyethylene terephthalate (PET) and polyamide were the dominant compounds in textile effluents, with PET being predominant in municipal WWTP effluents. Surprisingly, despite the municipal WWTP exhibiting higher efficiency in MP removal (ca. 71% compared to ca. 55% in textile industries), it contributed more to overall pollution. A novel bio-based flocculant, a cationic cellulose derivative derived from wood wastes, was developed as a proof-of-concept for MP flocculation. The novel derivatives were found to efficiently flocculate PET MPs, thus allowing their facile removal from aqueous media, and reducing the threat of MP contamination from effluents discharged from WWTPs.