Hybrid System Coupling Moving Bed Bioreactor with UV/O3 Oxidation and Membrane Separation Units for Treatment of Industrial Laundry Wastewater

Hybrid process combining ultrafiltration and electro-oxidation for COD and nonylphenol ethoxylate removal from industrial laundry wastewater

Laundry wastewater is a significant source of nonylphenol ethoxylate (NPEO) at wastewater treatment plants, where its breakdown forms persistent nonylphenol (NP). NP poses risks as an endocrine disruptor in wildlife and humans. This study investigates the degradation of NPEO and COD in industrial laundry wastewater (LWW) using a two-stage process combining ultrafiltration (UF) and electro-oxidation (EO). UF was used to remove suspended solids, while soluble COD (COD0 = 239 ± 6 mg.L-1) and NPEO (NPEO0 = 341 ± 8 μg.L-1) were oxidized by the EO process. Different operating parameters were studied such as current density, electrolysis time, type of cathode and supporting electrolyte concentration. Using an experimental design methodology, the optimal conditions for COD and NPEO3-17 degradation were recorded. This included achieving 97% degradation of NPEO3-17 and 61% degradation of COD, with a total operating cost of 3.65 USD·m-3. These optimal conditions were recorded at a current density of 15 mA cm-2 for a 120-min reaction period in the presence of 4 g·Na2SO4 L-1 using a graphite cathode. The EO process allowed for reaching the guidelines required for water reuse (NPEO <200 μg.L-1, COD <100 mg.L-1) in the initial laundry washing cycles. Furthermore, our results demonstrate that both NP and NPEO compounds, including higher and shorter ethoxylate chains (NPEO3-17), were effectively degraded during the EO process, with removal efficiencies between 94% and 98%. This confirms the EO process's capability to effectively degrade NP, the by-product of NPEO breakdown.

Waterborne transmission of protozoan parasites: a review of worldwide outbreaks - an update 2017-2022

The current study presents a comprehensive review of worldwide waterborne parasitic protozoan outbreaks reported between 2017 and 2022. In total, 416 outbreaks were attributed to the waterborne transmission of parasitic protozoa. Cryptosporidium accounted for 77.4% (322) of outbreaks, while Giardia was identified as the etiological agent in 17.1% (71). Toxoplasma gondii and Naegleria fowleri were the primary causes in 1.4% (6) and 1% (4) of outbreaks, respectively. Blastocystis hominis, Cyclospora cayetanensis, and Dientamoeba fragilis were independently identified in 0.72% (3) of outbreaks. Moreover, Acanthamoeba spp., Entamoeba histolytica, Vittaforma corneae, and Enterocytozoon bieneusi were independently the causal agents in 0.24% (1) of the total outbreaks. The majority of the outbreaks (195, 47%) were reported in North America. The suspected sources for 313 (75.2%) waterborne parasitic outbreaks were recreational water and/or swimming pools, accounting for 92% of the total Cryptosporidium outbreaks. Furthermore, 25.3% of the outbreaks caused by Giardia were associated with recreational water and/or swimming pools. Developing countries are most likely to be impacted by such outbreaks due to the lack of reliable monitoring strategies and water treatment processes. There is still a need for international surveillance and reporting systems concerning both waterborne diseases and water contamination with parasitic protozoa.

Removal of microfiber and surfactants from household laundry washing effluents by powdered activated carbon: kinetics and isotherm studies

Domestic laundry wastewater discharge contributes significantly to the presence of microfiber and surfactant pollutants in aquatic ecosystems, which have detrimental and toxic effects on humans and the environment. Investigating the efficacy of powdered activated carbon (PAC) in removing micro-/nanofibers with or without surfactant from household laundry effluent is the purpose of the current research. To simulate real-world scenarios, PAC adsorption kinetics and isotherms in laundry effluents under controlled conditions were studied. These studies showed that the kinetics obeyed a pseudo-second-order process and the isotherms varied between Langmuir and Freundlich models depending on the water types. In the results of experiments using distilled water and tap water, it was observed that the adsorption capacity was higher in tap water. When the adsorption of 0.1 μm filtered synthetic garments, detergent, and tap water was compared with the adsorption of the raw sample, it was observed that the adsorption capacity of the 0.1 μm filtered version was higher. Even though this study is preliminary, the results indicate that PAC has the capacity to serve as a viable approach for mitigating micro-/nanoplastic and surfactant contamination from laundry wastewater, thereby offering valuable guidance for advancing eco-friendly laundry techniques.

Management of greywater: environmental impact, treatment, resource recovery, water recycling, and decentralization

Wastewater generated from households can be classified into greywater and blackwater. Greywater makes up a substantial portion of household wastewater. Such water consists of wastewater released from kitchen sinks, showers, laundries, and hand basins. Since the greywater is not mixed with human excreta and due to the low levels of pathogenic contamination and nitrogen, it has received more attention for recycling and reusing in recent decades. Implementing decentralized greywater treatment systems can be an effective solution to overcome water scarcity by supplying a part of water requirement, at least non-potable demand, and decreasing pollutant emissions by eliminating long-distance water transportation in remote regions, like rural and isolated areas. This review focuses on greywater management in terms of reducing environmental risks as well as the possibility of treatment. Effective management of water reclamation systems is essential for a decentralized approach and to ensure the protection of public health. In this regard, the environmental impacts of disposal or reusing the untreated greywater are discussed. Furthermore, the most appropriate technologies that can be employed for the decentralized treatment of greywaters like constructed wetlands, waste stabilization ponds, membrane systems, and electrochemical technologies are described. Finally, this review summarizes resource recovery and sustainable resource reuse.