Domestic Wastewater Treatment Research Articles

Pilot study on the filling rate of parallel AA‐MBBR fillers in plateau areas

AbstractComparative analysis of the effects of different filling rates of polypropylene filler on the operational effectiveness, microbial abundance and diversity, and metabolism of the AA‐MBBR system for the treatment of domestic wastewater. The results showed that under the condition of the optimal filling rate of 40%, the average removal rates of BOD5, COD, NH3‐N, TN, and TP in the AA‐MBBR system were 93.63%, 90.02%, 81.25%, 80.07%, and 74.51%, respectively, and the effluent COD was 143.05 mg/L and the effluent NH3‐N was 37.03 mg/L; the number of operational taxonomic units (OTUs) in the AA‐MBBR system with the optimal fill rate was 595, which was higher than 10%, 20%, 30%, and 50%, and it was also found that the relative abundance of denitrifying bacteria (DNB) and polyphosphate bacteria (Paos) increased with the increase of biofilm fill rate, DNB increased by about 32.9% at TCL (fill rate) 40 compared to TCL10, Paos increased by about 21.6% at TCL30 compared to TCL10. the AA‐MBBR system with a fill rate of 40% showed better pollutant removal than the other systems with other fill rates The bacterial diversity was higher than that of the systems with other filling rates.

Animal Feedlots and Domestic Wastewater Discharges are Likely Sources of N-Nitrosodimethylamine (NDMA) Precursors in Midwestern Watersheds.

N-nitrosodimethylamine (NDMA) precursor concentrations along four major rivers in Minnesota, USA were quantified and correlated with watershed land cover types, anthropogenic activity, and organic matter characteristics. River water samples (36 in total) were chloraminated under uniform formation conditions (UFC) before and after lime-softening treatment, and the resulting NDMA concentrations were quantified (NDMAUFC). Regarding land cover, NDMAUFC in raw river water exhibited weak positive correlations with urban land (ρ = 0.33, p = 0.05) and cropland coverage (ρ = 0.35, p = 0.04). For anthropogenic activity, NDMAUFC in raw river water positively correlated with the number of feedlots (ρ = 0.57), total weight of animals (ρ = 0.68), and total number of domestic wastewater treatment plants (WWTPs; ρ = 0.63) with p < 0.01. NDMAUFC positively correlated with region IV fluorescence intensity from fluorescence excitation-emission spectra (ρ = 0.70, p < 0.01). Lime softening of river water typically increased NDMAUFC and preferentially removed organic matter that fluoresces in region V, suggesting that the organic matter in this region decreases NDMAUFC by competing for available chloramines. Overall, animal feedlots, along with domestic WWTPs, are predominant sources of NDMA precursors in the studied watersheds, while croplands and urban runoff are of lesser importance.

Performance of a Double-Filter-Medium Tandem Membrane Bioreactor with Low Operating Costs in Domestic Wastewater Treatment

To reduce the operating costs of conventional membrane bioreactors (MBRs) and improve the stability and quality of the dynamic membrane bioreactor (DMBR) effluent, a homemade inexpensive filter cloth assembly was connected to an up-flow ultra-lightweight-medium filter (UUF) in lieu of expensive membrane modules to form a double-filter-medium tandem (DT)-MBR. DT-MBR was used to treat domestic wastewater, and its removal efficiencies for chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus were similar to those of aerobic MBR, with average removal rates of 91.1%, 98.4%, 15.1%, and 50.7%, respectively. The average suspended solid (SS) of the final effluent was 5.6 mg∙L−1, and the filter cloth assembly played a leading role in SS removal, with an average removal rate of 86.0% and a relatively stable removal effect with little impact via backwashing. The activated sludge zeta potential, flocculation and sedimentation properties, particle size distribution, microbial compositions, extracellular polymeric substances (EPS), and filtration resistance of the cake layer were analyzed; it was found that the cake layer, which can also be called the dynamic membrane (DM), had an excellent filtration performance. However, the DM theory could not reasonably explain why the effluent quality of the filter cloth assembly maintained good stability even after backwashing. The real reason must be related to the sieving of cloth pores. Therefore, the concept of an in situ autogenous static membrane (ISASM) was proposed. With low operating costs and good and stable effluent quality, DT-MBR is a desirable alternative to the traditional MBR.

Nanofibrillated cationic cellulose derivatives as flocculants for domestic wastewater treatment

Natural-based coagulants have emerged as a reliable option to implement more sustainable operations and management of wastewater treatment plants. This work aims at evaluating the use of cationic nanofibrillated celluloses (cNFC) as novel bio-based flocculants to treat domestic wastewaters by the most widely employed treatment process – coagulation/flocculation. Two cNFC samples were prepared with different charge densities and tested as coagulant/flocculants using different water characteristics. The effect of cNFCs was studied by measuring the residual turbidity and dissolved organic carbon. The aggregation mechanism and kinetics of flocculation were also evaluated. Results show that cNFC can be used as an efficient flocculant to treat medium and high DOC waters since they considerably reduce turbidity (turbidity removals varied between 66.0 % and 85.7 % for the waters and cNFCs tested) without increasing dissolved organic carbon. Instead, cNFC removed dissolved organic carbon from domestic wastewaters (between 22.1 % and 65.5 % of DOC removals for the waters and cNFCs tested), which is a novel remarkable finding and a step forward in this knowledge area. High density charged cNFC revealed superior removal capacity at lower doses than the commercial coagulant FeCl3.

Biological pretreatment coupled gravity-driven membrane filtration for purifying decentralized domestic wastewater toward resource reuse

Membrane bioreactor (MBR) is an effective technology for the decentralized wastewater treatment; however, its high energy consumption and complex operation & maintenance limit its intensive application. This study introduced an innovative membrane-based process, gravity-driven membrane (GDM) filtration, to treat the decentralized wastewater without any cleaning procedures, and different biological pretreatments were constructed, including (I) tubular filler (TF-8), (II) tubular filler (TF-4), (III) fiber bundle filler (FBF), and (IV) sole aeration (control) to improve the filtration performance. The results indicated that the flux of GDM control can be maintained during long-term filtration in treating the real decentralized wastewater, and introducing the biological pretreatment processes could improve the stabilized flux of GDM without any influence on its stability. The average flux of TF-8/GDM was 3.69 ± 0.89 L m−2 h−1 during long-term filtration. Furthermore, coupling pre-treatment to GDM can effectively improve permeability quality and withstand the shock of water quality fluctuations. The average removal rates of chemical oxygen demand (COD) and dissolved organic carbon (DOC) by TF-8 were 59.7% and 48.3%, respectively. Besides, the organic contaminants could be further removed by the following GDM process owing to the biodegradation function of the self-formed biofilm on the membrane surface, and the DOC concentration in the GDM effluent can be reduced to as low as 4.5 mg L−1. Additionally, the elements of nitrogen (N) and phosphorus (P) could be effectively retention through the coupling process, with a retention rate of 84.3%–94.6% for total nitrogen (TN) and 99.8%–104.8% for total phosphorus (TP), respectively. Therefore, these findings can benefit to develop of new strategies to provide stable effluent quality, resource recovery, and energy consumption reduction in the membrane-based decentralized domestic wastewater treatment.

A pilot-scale study of a novel system for simultaneous nitrogen and carbon removal: technological advancement of a structured bed reactor with intermittent aeration (SBRIA) in real domestic sewage treatment.

This study outlines the development of an effective pilot-scale simultaneous denitrification and nitrification (SDN) system using intermittent aeration for the removal of carbon and nitrogen from real domestic sewage. Given the limited research in this area, the main objective was to evaluate the overall performance of the SBRIA system on a pilot scale and show its benefits in domestic wastewater treatment. The structured bed reactor with intermittent aeration (SBRIA) notably achieved 57% efficiency in removing total nitrogen without requiring external carbon sources. It also demonstrated impressive removal rates of 56% for total chemical oxygen demand (CODT) and 82% for biochemical oxygen demand (BOD5), indicating its effectiveness in degrading organic matter. In addition, the SBRIA showed high pH control and managed the consumption of alkalinity without the need for an alkalizer, maintaining consistent mean values of 7.7 ± 0.8 for pH and 166.8 ± 79.8 mg·L-1 for alkalinity. The system also proved resilient against toxic shocks caused by significant variations in influent characteristics. This study offers valuable insights and compelling results into a cost-effective and efficient treatment approach using an innovative technology not previously applied at the pilot scale. Its potential to remediate polluted water is substantial.

Analysis of fecal pollution load factor from septic tanks of residential area (study case: Bandung City, Indonesia)

According to the Ministry of Environment and Forestry, 2017, domestic waste is the most significant contributor to pollution sources in the Citarum watershed (62.16%) and Bandung City (94.15%). To overcome the problem, planning for infrastructure development and improvement of the domestic sewage treatment system is necessary. One of the essential characteristic parameters, which is the subject of this study, is the pollutant load factor parameter in the city of Bandung. Compared to sewage pipelines, the domination of domestic wastewater treatment in Bandung is the On-site Sanitation System (OSS) (38.47%), and the most widely used type of OSS is a septic tank. For this reason, thirty fecal sludge samples were taken from two fecal disposal points in Bandung City, and the concentrations of TSS, COD, BOD, and Ammonia were then analyzed. Based on the results of the study, the range of fecal sludge pollutant load factor for TSS in Bandung City is 57.28 g / person/day – 1,064 g / person/day with an average value of 546.39 g / person/day, the range for total COD is 30.06 g / person/day – 294.99 g /person/day with an average of 294.99 g / person/day, the total BOD range is 14.05 g /person/day – 504.97 g / person/day with an average of 175.5 g / person/day, and ammonia range 1.61 g/person/day – 3.11 g/person/day with an average of 2.62 g/person/day. Based on fecal sludge data, the result can be considered a recommendation to re-determine the main domestic wastewater pollution indicator generation. The new suggestions can be used to design an adequate domestic wastewater treatment system, especially in Bandung. The pollutant load factors can also be used to estimate the pollution loading of wastewater generated by present and future populations. It is important in urban growth planning.

Domestic Wastewater Treatment Using Natural Filtration and Solar Distillation Processes

Fresh water is most important daily requirement for human survival. On one hand many regions/countries are facing challenges related to availability of potable water for drinking and daily needs, on other hand water is wasted daily from different domestic applications. Processing and reuse of domestic waste water can help bridge gap between demand and supply. Present study describes a domestic waste water treatment process using combined natural filtration and solar distillation methods. In natural filtration process husk fibre, activated carbon and coconut husk fibre were used as filters. For solar distillation a pyramid shaped distillation unit is used. The samples of domestic waste water were collected from laundry, kitchen and house cleaning applications. The pH, TDS (total dissolved solids) and DO (dissolved oxygen) values of domestic waste water samples and water after treatment were tested. The results after treatment reveal that the values of TDS, pH, and dissolved oxygen are close to the standard values required for potable water which can be further used in different applications.

Potable Water Treatment and Reuse of Domestic Wastewater in the CMHC Toronto 'Healthy House'

Potable Water Treatment and Reuse of Domestic Wastewater in the CMHC Toronto 'Healthy House'

Проблемы накопления осадков сточных вод на территории канализационных очистных сооружений

The work is devoted to the study of environmental problems associated with the impact of sewage sludge on environmental components and the problems of recycling a mixture of sludge on the territory of the STP. Sewage sludge can be harmful to the environment if we do not take proper steps to dispose and treat it. The main impact on the soil during the accumulation of sewage sludge on sludge deposits of sewage treatment plants is exerted by such heavy metals as copper, cadmium, nickel, manganese, lead, zinc. Heavy metals, coming from the soil into plants and transmitted through food chains, have a toxic effect on plants, animals and humans. Therefore, it is necessary to introduce modern technologies and equipment for effective wastewater treatment in order to reduce the amount of sludge formation and methods of its treatment to reduce the negative impact on the environment and human health. The purpose of the work is to analyze the processes of waste treatment “a mixture of sludge from mechanical and biological treatment of domestic and mixed wastewater” at a sewerage treatment plants in order to minimize the negative impact on the environment, using the example of Irkutsk. An analysis of literature sources was carried out as part of a study related to the problem of wastewater disposal. Possible methods of disposal in Russia include: burial, pyrolysis, incineration, use in construction and use as fertilizer. As a result of the analysis of sewage sludge treatment at the Irkutsk STP, it can be concluded that the current method of sludge treatment using sludge cards is ineffective and has a negative impact on the environment. Based on the considered methods of treating sewage sludge, the vitrification method can be accepted as optimal, which can solve the problem of treating sewage sludge at the Irkutsk STP.

ВОДНЫЕ РЕСУРСЫ И ИХ ЭКОЛОГИЧЕСКОЕ СОСТОЯНИЕ (на примере реки Ак-Бууры)

According to the State Inspectorate for environmental and technical Safety under the Government of the Kyrgyz Republic, the republic has 145 facilities for the treatment of domestic and industrial wastewater, 22 municipal treatment facilities, mechanical and biological treatment of wastewater from enterprises and organizations to which the population is connected.The discharge of wastewater after passing through treatment facilities is carried out into the environ-ment. Of the 145 wastewater treatment plants: 14 are discharged into surface water bodies, 5 into dry streams and rivers, 2 onto terrain, 114 into irrigation and SDS [http: //data.movegreen. kg/indicator/49].Pollution of water bodies is no less dangerous than their depletion, and the deterioration of the sani-tary and environmental situation, together with the growth of wastewater, reduces the quality of water resources, as evidenced by the environmental insecurity of the population, which is closely related to the nature of the use of water resources.Wastewater bioremediation using algae and bacteria represent a significant potential for sustainable pollutant reduction, as well as contributing to resource recovery and valorisation of microalgae biomass and is known as a promising approach to water treatment and the Ak-Buura River. The use of consortia of microalgae and bacteria can provide several advantages over the use of microalgae monocultures alone for bioremediation treatment of various wastewaters, such as improved removal of nutrients or antibiot-ics and reduced risk of pollution.

A sustainable green solution to domestic sewage pollution: Optimizing floating wetland treatment with different plant combinations and growth media

Water quality degradation poses a global threat, with surface water resources bearing the brunt of pollution from various sources, including inadequately treated wastewater discharged from industrial and commercial processes. This discharge introduces a wide range of pollutants, compromising surface water quality and potentially contaminating groundwater. Floating Wetland Treatment (FWT) systems, particularly utilizing affordable and easy-to-construct bamboo rafts, emerge as a promising eco-technology offering a sustainable solution for rehabilitating water bodies polluted with inadequately treated domestic sewage. Research exploring the combined remediation potential of different plant combinations remains limited, although several studies demonstrate the efficacy of individual plant species in FWT systems. This study addresses this gap by evaluating the effectiveness of three terrestrial plant combinations (Canna indica, Chrysopogon zizanioides, and Hibiscus rosa-sinensis) supported by bamboo rafts in treating domestic wastewater. Among FWT methods, systems utilizing bamboo as floating rafts stand out due to their affordability, ease of construction, and adaptability to diverse plant species. FWT systems were meticulously designed with three plant combinations, utilizing soil and coco peat as growth media. Different FWT systems exhibited variations in their ability to remove several key water quality indicators. These variations were influenced by operational conditions, system design, plant selection, and growth media. Notably, the peat-based FWT system (FWT-BPCV) combining Canna indica and Chrysopogon zizanioides consistently demonstrated outstanding performance in reducing various pollutants, including total nitrogen (78.9 %), ammonia (90.2 %), total phosphorus (86.9 %), COD (92.8 %), BOD5 (94.8 %), TDS (70.7 %), TSS (93.6 %), turbidity (93.3 %), phosphate (73.2 %), electrical conductivity (62.5 %), and E. coli (78 %). This research suggests that FWT-BPCV is an eco-friendly wastewater treatment solution and an effective option for domestic wastewater treatment practices.

Building a database system of greenhouse gas emissions from concentrated domestic wastewater treatment plants in urbans of the Northern region to prepare for Vietnam's carbon market

In the field of wastewater treatment, a quality-assured carbon database system will serve as a basis for determining greenhouse gas emission quotas and aiming to prepare Vietnam's carbon market in the period from now to 2025. This article presents the results of calculations to determine the volume of greenhouse gas emissions (including emissions of methane CH4 and nitrous oxide N2O) from concentrated domestic wastewater treatment plants in urbans of the region North. The inventory calculation period is determined from the official operation of the plant to 2024. Total CH4 and N2O emissions during the calculation period of 29 plants correspond to normal emission scenarios (BAU) is 378.0 and 79.7 x 106 tons CO2e, low emission scenario is 363.8 and 6.4 x 106 tons CO2e, high emission scenario is 476.1 and 13,103.9 x 106 tons CO2e. On this basis, state management agencies as well as local authorities can propose the most appropriate and effective strategic directions for green growth urban development.

Prevention of environmental risks when designing wastewater treatment facilities

Economic development leads to increased negative impacts on the environment, including water resources. Domestic wastewater treatment plants are an integral part of the sustainable development of the infrastructure of settlements and cities. Treatment facilities are a multifunctional complex and are engineering and environmental protection structures, the activities of which are aimed at protecting surface water bodies. At the same time, this activity is associated with environmental risks and negative impacts on the environment. It is most effective to predict risks and develop effective engineering measures to prevent them at the design stage of technical systems. The purpose of the work is to identify possible environmental risks during the implementation of the life cycle and to propose the necessary engineering measures to prevent them when developing a wastewater treatment plant project. The article is the first to identify and systematize the main environmental risks at the stages of design, construction, operation and reconstruction of wastewater treatment facilities. A classification of environmental risks according to other criteria (frequency, predictability, degree of damage) is presented. Research has been carried out to model possible events at wastewater treatment plants and their connection with negative consequences for the environment. Recommendations have been developed for the prevention of environmental risks, including technological, production and operational, and organizational aspects of environmental protection.

Green Solution for Domestic Wastewater Treatment: Comparing Phytoremediation Potential of Four Macrophytes

Green Solution for Domestic Wastewater Treatment: Comparing Phytoremediation Potential of Four Macrophytes

Evaluation of different natural waste materials as bio-coagulants for domestic wastewater treatment

The process of removing pollutants from wastewater is a significant challenge for many countries due to the high cost of current technologies and the continuous increase in water consumption. Several methods are used to treat wastewater, but their efficiency varies according to the quality of the treated effluent and the technology used. In this study, seven natural waste materials: Moringa leaves, Chitosan, Opuntia, Pomegranate peel, Lupin straw, Sugarcane bagasse, and tea were prepared, characterized, and utilized as bio-coagulants for domestic wastewater treatment. Jar test experiments were carried out for the bio-coagulants using the coagulation/flocculation procedure. The optimum dose and time were tested for the bio-coagulants and the experiments were performed at pH 7.5 and at 25 °C. The presence of surface functional groups such as -COOH, -CN and –OH and the formation of surface adsorbents were characterized using Fourier transform infrared (FT-IR) spectroscopy and electron microscopy (SEM) analysis. All bio-coagulants were effective in removing contaminants from wastewater. The tested bio-coagulants removal efficiency increased with increasing doses until equilibrium was reached. The maximum removal percentage of Moringa, Chitosan, Opuntia, Pomegranate, Lupin, Sugarcane bagasse, and tea waste residue was observed at the optimal dose of 0.8 g/L. Pomegranate showed the highest pollutant removal efficiency. Chitosan and Lupin showed moderate efficiency for chemical oxygen demand (COD), biological oxygen demand (BOD5), total suspended solids (TSS), phosphate (PO4), ammonia (NH3), nitrate (NO3), turbidity, total Kjeldahl nitrogen (TKN), total nitrogen (TN), and total organic carbon (TOC). The highest adsorption capacities achieved for Opuntia in terms of TSS, COD, BOD5, PO4, NH3, NO3, TKN, TN, and TOC were 367.42, 625, 450, 82, 3.5, 3.83, 10.43, 8.21, 18.64, and 231.66 mg/g, with corresponding average removal efficiency of 85%, 88.25%, 88.07%, 90.32%, 90.29%, 93.82%, 90.23%, 92.23%, and 95.69%, respectively, due to the presence of cracked texture with porous adsorption sites. The research work suggested that the materials could be considered eco-friendly, low-cost, and effective bio-coagulants for wastewater treatment.

Energy Potential from Waste Activated Sludge in Domestic Wastewater Treatment Plant South Jakarta

Wasted activated sludge (WAS) a byproduct of wastewater treatment, holds significant untapped energy value. Conventional practice in DKI Jakarta involves collecting and directly disposing of WAS into landfill sites, overlooking the potential benefits of the sludge. Anaerobic digestion (AD) is a sustainable process that converts organic matter in the absence of oxygen offering a promising solution to harness this potential. The study aims to emphasize waste into energy by analyzing the volume of biogas through the Biochemical Methane Potential (BMP) value of WAS from the domestic WWTP in Setiabudi, South Jakarta. Characterization of WAS and its suitability for AD will be explored using DIN standards for 21 days. The experiment was duplicated into variants I1 and I2 and the parameters tested were pH, COD, TKN, VS, TS, concentration and volume of methane gas. In this study, the biogas yield from WAS obtained at 54,98 and 89,62 ml CH4/g VS along with the composition of biogas determined through GC readings at 61,78% CH4 and 56,08% CH4 from I1 dan I2, respectively. By optimizing AD processes, this study seeks to contribute to sustainable waste management and renewable energy production. Further research is needed regarding pre-treatment that may influence the formation of biogas.

Communication Strategy for Spald-T Development via YouTube in Haurwangi Village, Cianjur Regency

Domestic wastewater is a complex problem, but it is almost neglected and not managed, let alone a priority by the public and the government. This does not mean that there is no attention or treatment at all, but its management can still be identified as being carried out in inadequate achievements. This study aims to identify how the development communication strategy becomes an innovation that is beneficial for the surrounding community to solve a problem in terms of health that is packaged in development. The Centralized Domestic Wastewater Treatment System (SPALD-T) must begin with determining the right strategy, determined by considering the conditions of the planning area. This research method uses an approach technique with the results of an interview, observation, documentation and with the results obtained, namely the results of development and innovation that are obtained running smoothly. The results in this study that need to be taken are to seek onsite wastewater management because it is considered relevant, while to increase community participation in the development of domestic wastewater it needs to be coordinated by the KSM

Performance evaluation of gravity-driven bioreactor (GDB) for simultaneous treatment of black liquor and domestic wastewater.

A lab-scale gravity-driven bioreactor (GDB) was designed and constructed to evaluate the simultaneous treatment of black liquor and domestic wastewater. The GDB was operated with a mixture of black liquor and domestic wastewater at a ratio of 1:1 and maintained at an average organic loading rate of 1235mg-COD/L-Day. The wastewater was fed to the primary sedimentation tank at a flow rate of approximately 12mL/min and subsequently passed through serially connected anaerobic and aerobic chambers with the same flow rate. Each wastewater sample was allowed to undergo a hydraulic retention time of approximately 72h, ensuring effective treatment. The GDB was actively operated for nine samples (W1-W9) at a weekly frequency. The entire process was conducted within the workstation's ambient temperature range of 30-35°C to sustain microbial activity and treatment efficiency in an open environment. The performance of the GDB was evaluated in terms of various pollution indicators, including COD, BOD5, lignin removal, TDS, TSS, EC, PO43-, SO42-, microbial load (CFU/mL and MPN index), total nitrogen, and color reduction. The results showed that the GDB achieved promising treatment efficiencies: 84.5% for COD, 71.80% for BOD5, 82.8% for TDS, 100% for TSS, 74.71% for E.C., 67.25% for PO43-, 81% for SO42-, and 69.36% for TN. Additionally, about 80% reduction in lignin content and 57% color reduction were observed after the treatment. The GDB substantially reduced microbial load in CFU/mL (77.98%) and MPN (90%). This study marks the first to report on wastewater treatment from two different sources (black liquor and domestic wastewater) using a simple GDB design. Furthermore, it highlights the GDB's potential as a cost-effective, environmentally friendly, and efficient solution for wastewater treatment, with no need for supplementary chemical or physical agents and zero operational costs.

A Battery of Simple Bioassays for Domestic and Industrial Wastewater Treatment Plants in Konya, Turkey

Wastewater ingredients present risks to the environment and can cause health problems. The aim of this study was to identify the toxicological effects of influent and effluent wastewater from Konya Urban Wastewater Treatment Plant (KU WWTP) and Konya Organized Industrial Zone Wastewater Treatment Plant (KOI WWTP). Three different trophic level toxicity tests were conducted to determine the possible harmful effects of wastewater on the environment. The base toxic unit values of the Lepidium sativum toxicity test for the inlet and outlet samples of KU WWTP were found to be 1.43 and 1.10, respectively. Both values classified the analyzed wastewater into the “toxic” category. Wastewater entering the KU wastewater treatment facility was classified as “toxic” for the presence of toxic substances according to the Vibrio fischeri toxicity testing. Influent samples from the KOI wastewater treatment plant were classified as “toxic” with the Vibrio fischeri toxicity test. In addition, based on the fish bioassay value (TDF), wastewater from the KOI treatment facility was also classified as “toxic”. It was concluded that increased chemical oxygen demand and concentrations of total nitrogen and phosphorus and of certain heavy metals above the limits played a decisive role in classifying the samples as “toxic”. The results of this study suggest that all three tests have the potential to assess wastewater toxicity and that changes in wastewater properties may result in differences in test sensitivity.