Laundry Wastewater Research Articles

Potential of ceramic ultrafiltration membranes for the treatment of anionic surfactants in laundry wastewater for greywater reuse

Decentralized greywater treatment is gaining increasing recognition as an alternative for natural water supplies. Laundry wastewater in relatively large amounts of greywater is considered as a valuable resource with high reuse potential. However, organic pollutants with low molecular weights (e.g., anionic surfactants) that originate from laundry additives should be effectively removed. Because anionic surfactants are widely used to produce detergents, the retention of sodium dodecylbenzene sulphonate (SDBS; a typical anionic surfactant in laundry wastewater) was evaluated with a bench-scale ceramic ultrafiltration (UF) membrane filtration system. The results demonstrate that SDBS can be successfully retained with a ceramic UF membrane with a nominal pore size of 1 kDa (~4.0 nm) by carefully controlling several operating parameters. The dynamic phase changes of the surfactant that depend on its concentration affect the SDBS retention performances regardless of the operating parameters. At a high transmembrane pressure (TMP) and room temperature, the SDBS micelles that form on the membrane surface cause a pre-sieving effect induced by concentration polarization, thereby increasing the SDBS retention. As the solution pH increased, electrostatic repulsion between the solute and membrane surface induced higher SDBS retention rates. The retention rate also increased significantly with increasing ionic strength, which was especially pronounced with divalent ions than with monovalent ions because higher ion specificity could reduce the charge repulsion and induce their micellization. These electrostatic and adsorptive interaction could demonstrate a better understanding of surfactant retention mechanisms. Consequently, ceramic UF membranes have the potential of treating laundry wastewater attaining moderately high concentrations of surfactants.

Laundry Wastewater Treatment: Review and Life Cycle Assessment

Accommodation providers produce large amounts of wastewater in laundering processes (12–25 L/kg of textile). The composition of this wastewater depends on the washing procedure. Between 2 and 100 mg/L methylene blue active substances (MBAS), between 1 and 30 mg/L total phosphorous, and up to 20,000 mg/L chemical oxygen demand (COD) have been reported. Many regions have regulated the concentration of surfactants and phosphorous that can be discharged into water bodies to a few milligrams per liter, due to the negative effects that these compounds can cause in the environment. Several techniques can be employed in laundry wastewater treatment, including coagulation, filtration, biological reactors, adsorption, or advanced oxidation processes. Frequently, a combination of the mentioned processes is needed to meet the desired water quality standards. Only a few studies have reported an economic assessment of the options employed for laundry wastewater reclamation. Lower costs have been reported for coagulation, biological reactors, and adsorption processes than for other treatments such as filtration techniques. Total treatment costs vary between €0.09/m3 (treatment with granular activated carbon) and €5/m3 (nanofiltration). Life cycle assessment (LCA) is important for decision-making when different alternatives can be applied. Few references include a LCA for laundry wastewater treatment. Electricity consumption has been reported as one of the main environmental hazards for laundry wastewater treatment: an equilibrium must be reached between energy consumption and the standards of treated water. Future works must lead with the full-scale application and long-term monitoring of general, cost-effective, simple, and environmentally friendly techniques for the treatment of industrial laundry wastewater.

Towards Water and Energy Self-Sufficiency: a Closed-Loop, Solar-Driven, Low-Tech Laundry Pilot Facility (LaundReCycle) for the Reuse of Laundry Wastewater

In the scope of this study, a pilot facility for the recycling of laundry effluent was developed and tested. With the aim to enable nearly complete energy and water self-sufficiency, the system is powered by a photovoltaic plant with second-life batteries, treats the wastewater within the unit and constantly reuses the treated wastewater for washing in a closed cycle. The technology for wastewater treatment is based on a low-tech approach consisting of a physical/mechanical pre-treatment and biological treatment in trickling filter columns. The treatment process is operated in batch mode for a capacity of five washing cycles per day. During five weeks of operation water quality, energy consumption and production, water losses and washing performance were monitored. The system recovered 69% of the used water for the washing machine while treating the wastewater to the necessary water quality levels. The average COD removal rate per cycle was 92%. Energy analysis was based on modelled data of the monitored energy consumption. With the current set-up, an internal consumption rate of 80% and self-sufficiency of 30% were modelled. Future developments aim at increasing water and energy self-sufficiency and optimizing the water treatment efficiency.

Growth of Chlorella pyrenoidosa on different septic tank effluents from rural areas for lipids production and pollutants removal

Septic tank effluent from rural areas was an ideal medium for cultivating oleaginous microalgae. However, the characteristics of septic tank effluents varied greatly due to the different incoming wastewater, and bring uncertain risks for algal growth. In this study, an oleaginous microalgae was cultivated in septic effluents from different mixed wastewater. The results showed that the effluent from pure toilet wastewater was the best medium to achieve the highest biomass yield (1.68 g·L-1) and productivity (154.6 mg·L-1·d-1). In contrast, the discharge of kitchen or laundry wastewater reduced the biomass production by 50.5–79.1%. That caused much lower lipids production in effluents from mixed wastewater regardless of its high lipids content and saturation degree. The results suggest that the discharge of kitchen or laundry wastewater bring risks for biomass and lipids production, and should be separated from the toilet wastewater before entering into septic tank.

The effectiveness of anode variations for electrocoagulation and its application for laundry wastewater treatment

Since Diponegoro University moved its campus to the Tembalang area, it has been full of issues of decreasing groundwater quality and aesthetic decline caused by laundry wastewater and washing and toilet wastewater which has growing rapidly along with the growth of boarding houses in the Tembalang area. This will have an impact on the health quality of the people who live in the Tembalang area. This study aims to reduce the content of dissolved organic matter in laundry wastewater and bath wash also bath, wash and toilet wastewater. The method chosen was the electrocoagulation method, using 2 different electrodes. The electrodes chosen are aluminum metal and ferrous metal (as anode) and carbon (as cathode). With the electrocoagulation method using aluminum electrodes (as anode) and carbon (as a cathode) the amount of organic material that could be removed was 60.1%. Meanwhile, with ferrous metal (as anode) and carbon (as cathode) the amount of organic material that can be removed is smaller, namely 52.2%. The addition of 100 ppm NaCl solution and 100 ppm Na2SO4 solution was able to increase the efficiency of organic matter removal by 1.8-2.5%.

Use of Natural Coagulants in the Removal of Color and Turbidity from Laundry Wastewater

Use of Natural Coagulants in the Removal of Color and Turbidity from Laundry Wastewater

Parasitological and bacteriological survey of liquid wastes from Naze industrial clusters in Owerri, Imo state

Liquid wastes are known to be highly contaminated and pose great public health risk, especially when indiscriminately discharged to the environment. The parasitological and bacteriological survey of liquid wastes from Naze industrial clusters in Owerri metropolis was carried out. Sewage wastewater and laundry wastewater were used as study samples. 100mls each of the samples were collected from the drainage sites with sterile screw-capped specimen bottles, and sent to the laboratory for analysis. The liquid wastes were filtered and the filtrates were used for the analysis. Parasitological analysis employed Zinc Sulphate Centrifugal Flotation Technique and Modified Ziel-Nielsen stain (Acid-Fast Staining). Parasitic ova, cysts, larva and oocysts isolated were identified using standard morphological and taxonomic keys. Bacterial isolates were identified using standard microbiological techniques and biochemical characteristics where necessary. Parasites such as Ascaris lumbricoides, Strongyloides stercoralis, Trichuris trichiura, Enterobius vermicularis, Schistosoma mansoni, Hymenolepsis nana, Entamoeba histolytica, Gardia lamblia, Balantidium coll and Isospora belli were isolated from the liquid wastes. Bacteria species isolated included Erwinia amylovora, Listeria monocytogens, Escherichia coli, Salmonella typhi, Bacillus cereus, Staphylococcus aureus and Proteus vulgaris. The results showed that the most prevalent parasite and bacteria isolated were Ascaris lumbricoides 49(37.6%) and Salmonella typhi (3.38x104 CFU/mL) respectively. These potentially pathogenic parasites and bacteria detected in these liquid wastes, pose serious threat to public health. Interventive measures such as public health education, adequate drainage and waste disposal system, regular and monitored environmental sanitation, and provision of safe and portable water supply to the study area, are recommended.

Synthesis, characterisation and evaluation on the performance of ferrofluid for microplastic removal from synthetic and actual wastewater

Synthesis of ferrofluid without the addition of stabilizing agents or surfactants is an innovation of new method for microplastic removal. This study focuses on the ability of several types of oils as carriers and how they may improve the removal efficiency of the microplastic. The method is relatively low cost, simple and sustainable. The formation of ferrofluid involved the mixing of oil and iron oxide powder. The experimental work was commenced by adding 2 mm polyethylene terephthalate (PET) microplastics into synthetic ferrofluid. Then, the removal efficiency of microplastics was examined by varying the elements of ferrofluid based on three specific parameters, namely type of oil, volume of oil and dosage of iron oxide to obtain a standard formulation of the optimum results. Overall findings of the study indicated that the optimum formulation for ferrofluid preparation was at a ratio of 1:2.5 (volume of oil: dosage of magnetite) using lubricating oil which has successfully removed 99% of microplastic from water media. Subsequently, the physical and chemical properties of the prepared ferrofluid were also analysed using scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. Performance evaluation of the prepared ferrofluid on actual wastewater (laundry wastewater) revealed that 64% of microplastics were removed after treatment.

PENURUNAN KADAR CHEMICAL OXYGEN DEMAND (COD) DAN FOSFAT PADA LIMBAH LAUNDRY DENGAN METODE ADSORPSI

The large number of laundry in big cities also results in a lot of environmental pollution produced by these laundry services. Pollution from laundry services contains a lot of contaminants such as Chemical Oxygen Demand (COD), phosphate and so on. This study aims to examine how much the effectiveness of the type of media and the height of the media in removing COD and phosphate levels in laundry wastewater. The method applied is an adsorption system using activated carbon and zeolite media which is arranged in a series of laboratory scale reactors with media heights of 40 cm and 60 cm. The research reactor consisted of 4 reactors containing activated carbon and zeolite media. The results showed that the efficiency of COD levels using activated carbon media in reactor 1 was 72.48%. The highest efficiency for COD levels using zeolite media in reactor 3 is 64.55%. Meanwhile, for the phosphate content with activated carbon media, the reduction efficiency in reactor 2 was 92.09%, while the zeolite media with the highest efficiency was found in reactor 4, which was 96.44%. The media that was most effective in reducing COD levels was activated carbon media, while zeolite media was used to reduce phosphate levels. Moreover the height of the medium that was effective in reducing COD levels was activated carbon with a height of 40 cm, while lowering the levels of phosphate was a zeolite with a height of 60 cm.

INFLUENCE OF Ba SUBSTITUTION IN SrTiO3 PEROVSKITE: STUDIES OF PHOTOCATALYSIS AND CATALYTIC BIGINELLI REACTION

Crystalline Barium substituted Sr1-xBaxTiO3 (x =0.0, 0.04, and 0.08) system nanomaterials were successfully prepared via modified sol-gel citrate precursor technique at 800˚C temperatures. A comparative study of the structural, morphological, optical properties and catalytic activity is reported. Synthesized nanomaterials were analyzed by X-ray diffraction and FTIR. Pristine SrTiO3 compound found to be cubic structure. On substitution of Ba in Sr-site, the slight distortion in XRD diffraction peaks were observed. Photo-catalytic efficiency using UV-Visible Spectroscopy was investigated by photo-degradation of synthetic dye in Laundry wastewater employing solar light, and found to be promising photo-catalysts. The catalytic potentiality was also explored for the synthesis of dihydropyrimidinone using Biginelli reaction and the product was found to increase upto 20% for Sr0.2Ba0.8TiO3 with the highest concentration of Barium.

Water recovery and on-site reuse of laundry wastewater by a facile and cost-effective system: Combined biological and advanced oxidation process

Combined biological and physicochemical process was selected for treatment of laundry wastewater. The results show that after microbial adaptation, almost 91% of COD was removed at food to microorganism (F/M) ratio of 0.12 gBOD/gMLSS·d. Dehydrogenase activity of the biomass showed an increasing trend and finally reached 3.8 μgTFgbiomass.d corresponding to the highest process performance. 16SrRNA fragment and phylogenetic analysis identified Pseudomonas pharmacofabricae and Bacillus spp. as the dominant bacteria. The effluent of the biological process was then injected into the UV/O3 process for complete removal of residual COD and detergent. Finally, microfiltration and ultrafiltration were used to remove any remaining suspended solids. The operating cost analysis showed that 0.65 €/m3 treated wastewater is required for treatment of the laundry wastewater. Accordingly, the suggested combination of the biological and physicochemical process could be a promising and highly efficient process for treatment and reuse of laundry wastewater.

Correlation between faecal indicator bacteria in diarrheagenic stools and hospital wastewaters: Implication on public health

Background: Hospital wastewaters contain blends of inorganic, natural constituents and contaminants that carry significant health risk when released directly into the environment. The aim of this study is to investigate the correlation between faecal indicator bacteria in diarrheagenic stools and wastewaters generated in University of Medical Sciences Teaching Hospital complex, Akure, Nigeria.Methodology: Quantification of faecal indicator bacteria was carried out on diarrheagenic faecal samples collected from 55 hospitalized patients and 68 wastewater samples from the medical laboratory science and laundry units of the hospital over of period of 12 weeks. Standard membrane filtration technique was performed using membrane intestinal enterococcus (m-ENT), membrane faecal coliform (m-FC), membrane lauryl sulphate (MLSA), eosin methylene blue (EMB) and Salmonella-Shigella (SS) agar plates, which were incubated at 37ºC for 24 hours (MLSA, EMB and SSA), 44ºC for 24 hours (m-FC); and 37ºC for 48 hours (m-ENT). Bacterial colonies on agar plates were counted and expressed as colony forming units (CFU) per 100ml of diarrheagenic stool and wastewater. Pearson’scorrelation analysis was used to determine the relationship between the level of faecal indicator bacteria in diarrheagenic stools and wastewaters at p<0.05 level of significance (and 95% confidence interval).Results: The faecal coliform counts (log 10 CFU/100ml) ranged from 1.18 to 1.54 in diarrheagenic stools, 1.32 to1.64 in laboratory wastewater and 1.08 to 2.19 in laundry wastewater. Escherichia coli count (log 10 CFU/100ml) ranged from 1.08 to 1.40 in diarrheagenic stools, 1.20 to 1.86 in laboratory wastewater and 0.30 to 1.81 in laundry wastewater. Intestinal enterococci count (log 10 CFU/100ml) ranged from 0 to 0.30 in diarrheagenic stools, 0.78 to 0.90 in laboratory wastewaters and 0.48 to 1.11 in laundry wastewaters. Pearson’s correlation co-efficient showed that all the faecal indicator bacteria count in diarrheagenic faecal samples exhibited positive correlation with those in laboratory wastewaters, but not with those from laundry wastewaters.Conclusion: The findings suggest that diarrheagenic stools should be properly disinfected after the performance of laboratory tests to prevent transmission of potential pathogens, and wastewater generated from hospitals should be treated prior to discharge into the environment, to prevent possible infections in the community.
 Keywords: Correlation, faecal indicator bacteria, public health, transmission, wastewater

SUSTAINABLE RECYCLING OF HOTEL WASTE WATER IN GOA

Goa, a tourist destination known for its alarming scenic beauty has seen a consistently rising trend in hotel occupancy for star category hotels. On an average a luxury hotel would consume approximately 200,000 litres of water per day. The waste water generated from this consumption is basically 30% of black water (sewage) and 70% of grey water (bath water, laundry waste water, etc). A study was carried out to harness the potential of grey water before dumping into water bodies per se. A membrane based bio reactor (MBR) designed for chemical and biological treatment of this waste water includes mechanisms like coagulation, flocculation & separation of the water ludge. The water is then validated for its BOD & COD levels as per the government norms and then membrane filtered to remove total dissolved solids (TDS). This filtered water is then subjected to biological treatment whereas the sludge is used in landfills. EM technology uses commercially available culture of microorganisms, comprising of Lactobacillus, photosynthetic bacteria and yeast for biological treatment of the waste water to render it safe for human use. Monitoring and water quality analysis revealed that microbial treatment considerably reduced the BOD. This innovative technology allows the recycling of waste water which can be made use of for different purposes like gardening, cleaning floors & hotel properties, washing of cars & flushing. Moreover, it requires low foot print and involves easy installation and less maintenance. Recycling of grey water would in turn curtail consumption, thus cutting cost for purchase of water and ensuring safety of consumers. In addition to MBR & EM Technology being economically feasible, safe and user-friendly, its usage is highly recommended to maintain a stable water table and preserve the integrity of the hospitality industry in Goa. It is surely an initiative to minimize water crisis thus maintaining a sustainable ecosystem.

Deep purification of pretreated laundry wastewater through the adsorption by polymeric composites and optimisation of the process

ABSTRACT In the article, the treatment of pre-treated laundry wastewater by adsorption method was studied through the experimental design. The composites of the polyaniline-supported activated carbons produced from sunflower seed hulls (PAn/SH) were used as adsorbents. Characteristics of the adsorbents were determined with the help of scanning electron microscopy, Fourier-transform infrared spectroscopy and elemental analysis. Experimental design was used to determine the effects of pH (4–12), reaction time (5–150 min), adsorbent amount (0.3–1.5 g) and mixing rate (50–200 rpm) on the process efficiency. Monitoring of the efficiency was held in terms of detergent and chemical oxygen demand removals. Response surface methodology based on the four-variable-three-level Box–Behnken design was used to interpret the adsorption properties of laundry wastewater on COD and detergent removal efficiencies. The removal efficiencies of the adsorption process were evaluated regarding to the experimental design and also Pareto analysis was applied for profiling the percentage effect of the independent variable on the response for the study. Accordingly, the most effective factors were computed as the amount of adsorbent (82%) in detergent removal and the mixing rate (31%) in COD removal, where pH was the second effective factor for both. The highest efficiencies of the MBAS and COD removals were achieved as 95% and 74% in the 24th run, respectively. In the treatment of laundry wastewater by adsorption method, using PAn/SH produced from the sunflower seed hulls as an adsorbent will be an alternative method.

Synthesis of hydrochars derived from industrial laundry sludge and its application in the removal of cationic dye

The textile industry generates large amounts of effluents, often treated by coagulation/flocculation. The tannin-based coagulants produce a high-quality treated effluent and a more biodegradable sludge. Efforts have been made to reuse the sludge, however, the synthesis of hydrochars and activated hydrochars from this residue was never evaluated before. Therefore, this study aimed to produce a novel sludge-based adsorbent, through hydrothermal carbonization (HTC) and KHCO₃ activation, from real laundry wastewater treated with tannin (Tanfloc SG), in order to remove methylene blue (MB) from aqueous solutions. Tanfloc SG coagulant was more effective to reduce color and turbidity than chemical oxygen demand. The best coagulant concentration (140 mg L−1) was selected to produce sludge, the hydrochar (HC-S), and activated hydrochar (AHC-S). The characterization demonstrated that activation volatilized the organic matter, leaving coke and inorganic solids. However, despite the lower carbon content, AHC-S presented a notorious surface area (3005.57 m² g−1). Minerals were presented in the adsorbents and AHC-S showed graphene-like layers. Regarding MB adsorption, pseudo-second-order and Langmuir models fitted kinetic and equilibrium data, respectively. HC-S and AHC-S obtained qmax of 69.77 and 808.83 mg g−1, respectively, and the latter was higher than other activated hydrochars, demonstrating the potential of the adsorbent.

Using electric flocculation to treat domestic laundry wastewater with different types of detergents

Laundry wastewater contains a large number of surfactants, suspended solids and other pollutants, and the COD value is high. If the wastewater is discharged into the water without harmless treatment, it will cause serious environmental pollution. The electrocoagulation process was selected as a promising environmentally friendly technology for treating domestic laundry wastewater. In this paper, the contribution of the liquid and powder detergents to the composition of domestic laundry wastewater was investigated. Combination of stainless steel and aluminum anode electrodes were compared. The effect of electrolysis time and current density on the removal of COD, LAS and turbidity of liquid detergent and powder detergent laundry wastewater were evaluated. The experimental results showed the electrocoagulation process has significant removal. It was found that the electrolysis time in 25 minute, current density in 5 mA/cm2 had optimum efficiency when considering efficient removal and economic energy consumption. For Liquid detergent laundry wastewater, COD, LAS and turbidity removal rates were 84%, 93% and 96%. For powder detergent laundry wastewater, COD, LAS and turbidity removal efficiency were 80%, 83% and 91%, respectively. Energy consumption in the optimum conditions for liquid detergent and powder detergent laundry wastewater by electrocoagulation were 7.324KWh/m3, 3.642KWh/m3, respectively, while using combination of stainless steel and aluminum anode electrodes equals 1 to 1.

Laundry wastewater characteristics and their relationship with river water quality as an indicator of water pollution. Case study: Code Watershed, Yogyakarta

Laundry services are rapidly becoming ubiquitous in rural and urban areas, generating high domestic waste volumes. Their growth has raised concerns about the quality of natural waters, particularly the rivers into which most laundry businesses discharge their wastewater. The research set out to study laundry wastewater characteristics and their relationship with the river water quality as water pollution indicators in Code Watershed (Indonesia). It lies in three administrative units where many human activities take place in the watershed’s upper to the lower reaches. BOD and COD of 25 sampled laundry businesses were analyzed descriptively and compared to the laundry wastewater standards stipulated in Regulation No. 7 of 2016 and the class II water quality standards issued in Governor Regulation No. 20 of 2008. The results showed that the BOD of four laundry businesses and the COD of 18 laundry businesses exceeded the predetermined standards. Overall, rivers in Code Watershed meet the class II river water criteria for BOD at three of the seven sampling points and COD at all points.

UV/O3 and UV/H2O2 processes in the decomposition on waste streams generated during membrane filtration of laundry wastewater

UV/O3 and UV/H2O2 processes in the decomposition on waste streams generated during membrane filtration of laundry wastewater

EFFECTIVENESS OF "SM" TOOL TO REDUCE DETERGENT LEVELS IN LAUNDRY WASTEWATER

Introduction: The use of detergent every year is increasing in line with the population growth rate in Indonesia. The impact of excessive use of detergent will result in pollution and damage to ecosystems and aquatic biota. The nature of detergents is to damage microorganisms. The dominant laundry waste comes from softeners and detergents. The research aimed to analyze the effectiveness of the "SM" tool to reduce detergent levels in laundry wastewater. Methods: This type of research was pre-experimental with a one-shot case study design. The independent variable was a tool to recycle laundry liquid waste into clean water "SM." The dependent variable was the detergent level (MBAS). The sample came from the laundry in the Kecamatan Baturraden area. Replication was carried out six times. Analyzing differences in detergent levels before and after being treated with the "SM" tool. The analysis used a paired T test. Result and discussion: The experimental results showed the “SM” tool could treat 960 liters of wastewater/day. The physical quality of the water after being treated using the “SM” tool, the water was colorless or clear, but it still smelled slightly fragrantly. The average level of detergent level checks before processing was 2.52 mg/L and after processing was 0.01 mg/L. The effective detergent parameter (MBAS) decreased by 99.51%, categorized as quite effective. The analysis using the paired T Test showed the p value of 0.239 with the lower and upper values being at one pole, meaning there was a significant difference between detergent levels before and after being processed utilizing the "SM" tool. Conclusion: Detergent levels (MBAS) after processing met the chemical quality requirements of clean water in accordance with Regulation of the Minister of Health Number 32 of 2017 concerning Environmental Health Quality Standards and Water Health Requirements for Sanitation Hygiene, Solus Per Aqua and Public Bathing Needs.

An innovative evaluation method based on polymer mass detection to evaluate the contribution of microfibers from laundry process to municipal wastewater

Clothes washing releases numerous microfibers, including microplastic fibers (MPFs). Although MPFs in laundry wastewater are an important source of microplastics (MPs) in wastewater treatment plants (WWTPs), credible quantitative assessments of their contributions remain limited. Polyester fiber is the most important textile fiber. Its component, polyethylene terephthalate (PET) polymer, can be quantified by liquid chromatography–tandem mass spectrometry (LC-MS/MS). The release of MPFs from polyester clothes through washing was quantified via simulation experiments, and the MPFs in two WWTPs were measured by microscopic counting and LC-MS/MS. Direct comparison of the abundances of PET MPFs in laundry wastewater and WWTP influents led to an undervalued contribution rate of 9%−11% of the PET MPFs in laundry wastewater to those in WWTP influents. However, comparison of the mass of PET MPFs in laundry wastewater and WWTPs influents revealed that the PET MPFs from laundry contributed approximately 50% of those in the WWTPs. The latter was confirmed by comparing the number of polyester fibers released during clothes washing to the calculated number of “model MPFs” in WWTPs according to the PET mass concentration. Based on the PET concentration, the annual discharge of PET MPs from WWTPs to the water environment could also be estimated.