Toxicity Reduction Evaluation Research Articles

Biological treatment of leachate from the uncontrolled landfill: evaluation of toxicity and heavy metals reduction

ABSTRACT This work assesses the efficiency of biological processes in reducing leachate toxicity, using tests of phytotoxicity, cytotoxicity and heavy metals assay. Concerning metal load of raw leachate, iron is the most abundant with a value of 77.23 mg/L; combined treatment is most effective in reducing metals with abatement rates of: Al (94.96%), Fe (99.23%), Pb (90.53%), Sn (90.25%) and Zn (90.43%). The phytotoxicity of raw leachate is total against all tested seeds, this phytotoxicity was decreased after treatment with SBR, and the germination indices are between 3.60%−65.36%, 0.25%−39.99% and 5.36%−35.55% respectively for Daucus carota, Lactuca sativa and Hordeum vulgare seeds. Leachate treated with the combined treatment exhibits no inhibition of germination even at concentrations of 100%. Regarding cytotoxicity assessed via Brine Shrimp test, raw leachates were cytotoxic killing all Artemia salina larvae even at low concentration of 1%. After the treatments, cytotoxicity of leachate was decreased especially in leachate treated by SBR and combination with inhibition percentages up to 16.66%. The experimental results obtained were confirmed using PCA which showed that the SBR and combination treatments have common purification characteristics and also the inverse correlation between heavy metal concentrations and germination indices indicate that these metals are involved in leachate toxicity.

Applications of the RTgill-W1 Cell Line for Acute Whole-Effluent Toxicity Testing: In Vitro-In Vivo Correlation and Optimization of Exposure Conditions.

The cell line RTgill-W1 was evaluated as an in vitro alternative model for acute fish whole-effluent toxicity (WET) testing. We determined the 50% effective concentration (EC50) that reduces the viability of RTgill-W1 cells for selected toxicants commonly found in effluent samples and correlated those values with the respective 50% lethal concentration (LC50) of freshwater (fathead minnow, Pimephales promelas) and marine (sheepshead minnow, Cyprinodon variegatus) fish species obtained from the literature. Excluding low water-soluble organics and the volatile sodium hypochlorite, significant correlations were measured for metal, metalloids, ammonia, and higher water-soluble organics between in vitro EC50 values and in vivo LC50 values for both species. Typically, toxicity studies with RTgill-W1 cells are conducted by adding salts to the exposure medium, which may affect the bioavailability of toxicants. Osmotic tolerance of RTgill-W1 cells was found between 150 and 450 mOsm/kg, which were set as the hypoosmotic and hyperosmotic limits. A subset of the toxicants were then reexamined in hypoosmotic and hyperosmotic media. Copper toxicity decreased in hyperosmotic medium, and nickel toxicity increased in hypoosmotic and hyperosmotic media. Linear alkylbenzene sulfonate toxicity was not affected by the medium osmolality. Overall, RTgill-W1 cells have shown potential for applications in measuring metal, metalloids, ammonia, and water-soluble organic chemicals in acute WET tests, as well as complementing current toxicity identification and reduction evaluation strategies. In the present study, RTgill-W1 cells have been established as a valid animal alternative for WET testing, and we show that through manipulation of medium osmotic ranges, sensitivity to nickel was enhanced. Environ Toxicol Chem 2021;40:1050-1061. © 2020 SETAC.

Treatment of effluent containing thiamethoxam and efficiency evaluation of toxicity reduction

ABSTRACT The treatment of seeds using pesticides is a widely employed technique that generates effluents with high contamination potential. In the present study, our objective was to characterize and evaluate the toxicity of washing wastewater from corn seed treaters that contained the pesticide thiamethoxam. Effluents were treated by adsorption using several adsorbent materials, namely activated vegetable carbon, corn straw, and soybean hulls, different pH, and distinct mass concentrations for each material. The activated carbon promoted a greater reduction in the chemical oxygen demand (COD). In the coagulation-flocculation treatment, with ferric chloride (FeCl3) and poly-aluminum chloride (PAC), and using factorial planning with the concentration of FeCl3 and the sedimentation time as independent variables, the best COD removal occurred with 850 mg L−1 FeCl3 and 120 min sedimentation. The treatments C (coagulation), CACA (coagulation followed by adsorption with activated vegetable carbon), and CACS (coagulation followed by adsorption with corn straw) presented the most efficacious physicochemical parameter changes. The CACA treatment showed the best result for removing thiamethoxam. Nevertheless, raw and treated effluents showed high toxicity to the bioindicators Artemia salina L. (immobility/mortality test), Eisenia fetida (avoidance test), and Allium cepa L. (cytotoxicity test). The effluents also produced a mutagenic effect for A. cepa, due to the presence of chromosomal changes. The results demonstrated the risk that this effluent can cause to the environment. These data highlight the need to investigate new technologies to reduce the physicochemical parameters, the agrochemical levels, and, in particular, the final effluent toxicity.

Evaluation of toxicity reduction in textile effluent by different treatment protocols involving marine diatom Odontella aurita on freshwater fish Labeo rohita

Raw textile effluent, collected from Common Effluent Treatment Plant (CETP), Perundurai, Tamil Nadu, was subjected to toxicity reduction employing varied laboratory treatment protocols viz. chemical (Advanced Oxidation Process), physical (Electrocoagulation), bacterial (Lyisinibacillus sphaericus), phycoremediation (Odontella aurita) and their combinations. Aquatic toxicity was tested using freshwater fish Labeo rohita and the variations in fish histopathological, biochemical, enzymology, hematological and immunological parameters were analyzed. The intermediatory dye metabolites and secondary amines produced during chemical (96hLC50=5%) and bacterial remediation (96hLC50=15%) had enhanced the stress factor and organ damage in the exposed fish. In phycoremediation, though the newly explored Odontella aurita could effectively absorb metal ions than other algal species and moderately reduce effluent physical parameters, but was less efficient in the removal of azo dyes from the effluent (96hLC50=50%). Subsequent physical remediation had removed these dyes and other effluent solid sludge, and had enabled the fish to survive acute toxicity (96h+). However, it was less efficient in removing the secondary metabolites produced during bacterial (96hLC50=20%) and chemical (96hLC50=25%) remediation. Secondary phycoremediation had effectively reduced effluent physical parameters, metal ions and the hydroxyl radicals left over after primary chemical remediation. Therefore, this combined chemical and phycoremediation processes had enabled the fish population survive short term chronic toxicity (168h+), with less organ damage and slightly enhanced immunological response. This treatment is certainly better than the methodology adopted by CETP, where the fish could survive only acute toxicity with higher organ damage.

Assessment of the toxicity of wastewater from the metalworking industry treated using a conventional physico-chemical process.

This article presents results from a toxicity reduction evaluation program intended to describe wastewater from the metalworking industry that was treated using a conventional physico-chemical process. The toxicity of the wastewater for the microcrustacean Daphnia magna was predominantly expressive. Alkaline cyanide wastewater generated from electroplating accounted for the largest number of samples with expressive toxicity. When the raw wastewater concentrations in the batches were repeated, inexpressive toxicity variations were observed more frequently among the coagulated-flocculated samples. At the coagulation-flocculation step, 22.2% of the treatments had reduced acute toxicity, 30.6% showed increased toxicity, and 47.2% remained unchanged. The conductivity and total dissolved solids contents of the wastewater indicated the presence of salts with charges that were inappropriate for the survival of daphnid. The wastewaters treated by neutralization and coagulation-flocculation had average metallic compound contents that were greater than the reference toxic concentrations reported in other studies, suggesting that metals likely contributed to the toxic effects of the wastewater on freshwater microcrustaceans. Thus, alternative coagulants and flocculants should be assessed, and feasible doses should be determined to improve wastewater treatment. In addition, advanced treatment processes should be assessed for their abilities to remove dissolved toxic salts and ions.

生物応答を用いた排水評価・管理の動向と今後の展望

In 2009, Ministry of the Environment, Japan, started the discussion about the implementation of bioassay to evaluate and control toxic chemical compounds in effluent and ambient water to complement the conventional chemical analysis of individual compounds, and is aimed to start the new system under Water Pollution Control Act as early as 2016. In this manuscript, the summary of the draft test manual, publicized by National Institute for Environmental Studies (NIES) in 2013, is presented, and then the current status of effluent management in other countries is summarized. There are still several difficulties in implementing the new system using bioassay such as the increase of the cost, the shortage of testing laboratories, the establishment of the benchmark, and toxicity reduction evaluation. Some of the solution measures are presented in addition to the authors' expectation for the implementation of this approach and the contribution of Reference Laboratory in NIES.

Abamectin Degradation by Advanced Oxidation Processes: Evaluation of Toxicity Reduction Using Daphnia similis

AbstractThis work evaluated the toxicity reduction of abamectin in an aqueous solution (500 μg L

경기지역 산업시설 방류수 생태독성 영향 평가

Objectives: Industrial development in Korea results in a rapid increase in the number of chemicals, some of which may be responsible for toxicity to aquatic ecosystems. In addition, the types of hazardous chemicals included in industrial effluents have gradually increased. Therefore, chemical analysis alone is not enough to assess ecological effects of toxic chemicals in wastewater. Methods: In response to new regulations as whole effluent toxicity (WET) tests for effluent discharge of 15 publicly owned treatment works (POTWs) and 25 industrial effluent treatment plants in Gyeonggi-do, which will be effective from 2011, a necessity of studies emerges that investigates toxicity levels. Results: In case of the public treatment plants, none of them had exceeded the criteria for ecotoxicity. As for individual wastewater discharge facilities, on the other hand, two types were found to exceed the criteria: pulp and paper manufacturing facilities and pharmaceutical manufacturing facilities. For the pulp and paper manufacturing facilities, monitoring results could not help determine the exact toxicant identification. However, Daphnia magna inhibition effect or death was found to leave white plums, suggesting that suspended solids treated and the polymer used in coagulant dose. In case of pharmaceutical manufacturing facilities, the general water quality parameters cannot affect Daphia magna. However, conductivity and salinity can have an effect to be 14,000 <TEX>${\mu}s/cm$</TEX>, 8.1‰ by salts, respectively. Toxicity Identification Evaluation (TIE) and Toxicity Reduction Evaluation (TRE) procedures results appeared to be effective for identifying toxic compounds in <TEX>$Cl^{-}$</TEX> and <TEX>$SO_4^{2-}$</TEX>. Conclusions: It is necessary to develop control measures for water treatment chemicals and salts used for processes such as coagulation in individual wastewater discharge facilities in order to achieve the goal to protect aquatic ecosystems in public waters.

Bioassay evaluation of toxicity reduction in common effluent treatment plant

This paper investigates the utility and validity of bioassay toxicity testing using Daphnia magna straus as test organism for monitoring the common effluent treatment plant (CETP) receiving both industrial as well as domestic effluent. The average daphnia toxicity (Gd) at inlet, after primary settling tank (PST), secondary settling tank (SST) and tertiary treatment unit were reported as Gd-16, Gd-12, Gd-4 and Gd-1 respectively. However, a cumulative percentage removal in toxicity after PST, SST and tertiary treatment units was observed as 25%, 75% and 100%, respectively, during entire study period. It showed that a complete removal in daphnia toxicity (Gd) i.e.100% had been achieved only after tertiary treatment unit involving Dual Media Filters followed by activated carbon filters. Further attempts have been made to establish the relationship between key wastewater constituents i.e. Chemical Oxygen Demand (COD) and Suspended Solids (SS) with respects to daphnia toxicity (Gd). It was observed that COD and SS show a statistically significant correlation (r2) with daphnia toxicity (Gd) i.e. 0.89 and 0.81, respectively. Thus COD and SS can serve as a regulatory tool in lieu of an explicit toxicity standard (to check and improve the operational status of wastewatertreatment plants in time).

Toxicity-directed approach of polyester manufacturing industry wastewater provides useful information for conducting treatability studies

A broader characterization of industrial wastewaters, especially in respect to hazardous compounds and their potential toxicity, is often necessary in order to determine the best practical treatment (or pretreatment) technology available to reduce the discharge of harmful pollutants to the environment or publicly owned treatment works. Using a toxicity-directed approach, this paper sets the base for a rational treatability study of polyester resin manufacturing. Relevant physical and chemical characteristics were determined. Respirometry was used for toxicity reduction evaluation after physical and chemical effluent fractionation. Of all the procedures investigated, only air stripping was significantly effective in reducing wastewater toxicity. Air stripping in pH 7 reduced toxicity in 18.2%, while in pH 11 a toxicity reduction of 62.5% was observed. Results indicated that toxicants responsible for the most significant fraction of the effluent's instantaneous toxic effect to unadapted activated sludge were organic compounds poorly or not volatilized in acid conditions. These results led to useful directions for conducting treatability studies which will be grounded on actual effluent properties rather than empirical or based on the rare specific data on this kind of industrial wastewater.

Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater

Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox ® bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity.

Biological and Electrochemical Treatment of Used Metalworking Fluids: A Toxicity-Reduction Evaluation

The aim of this study was to evaluate and compare the toxicity of spent metalworking fluids (MWFs) and two different effluents obtained by biologic and electrochemical treatment of spent MWFs toward aquatic organisms of different trophic levels. The obtained toxicity data was used to calculate safe concentrations of both effluents. The spent MWFs without treatment showed the highest toxicity among the tested samples and should be classified as "extremely toxic" (toward invertebrates) or "very toxic" (toward other test organisms). Both methods applied for MWFs treatment resulted in a significant decrease in toxicity of the treated MWFs, but the obtained effluents had still to be regarded as "toxic". The ranges of the values of acute toxic units for both effluents were significantly narrower than for the untreated spent MWFs. The values of the safe concentrations of the spent MWFs, the biologic effluent, and the water phase resulting from electrochemical emulsion breaking were equal to 0.013%, l.8%, and 1.3%, respectively, corresponding to chemical oxygen demand concentrations of 1.8%, 32, and 34 mg O(2)*L(-1). These values are far lower than the discharging limit of 125 mg O(2)*L(-1) for industrial effluents, according to the relevant Polish regulations. It is therefore recommended to include toxicity bioassay parameters into guidelines for wastewater discharges to surface waters because the existing chemical and physical parameters are not sufficient to describe the environmental impact of industrial wastewater. Toxicity bioassays can be a promising tool for evaluating the efficacy of unit operations in industrial wastewater treatment (toxicity reduction evaluation) as well as identification of toxic substances in effluents (toxicity identification evaluation).

Evaluation of Decolorization, Mineralization, and Toxicity Reduction of Tropaeolin O in Water by Ozonation with UV Irradiation

The combination of ozonation with UV irradiation can remove Tropaeolin O (AO6) and its by-products effectively and completely. The ozone dose affects the rate of decolorization, AO6 species removal, and dissolved organic carbon (DOC) reduction significantly. After 240 minutes of ozonation, the average DOC removal efficiency (ηDOC) for O3 alone was about 0.79, while ηDOC for O3/UV was 1.0. The average DOC removal rate was low at early stage of ozonation due to decolorization and low DOC. At later stage of ozonation, average DOC removal rate decreases because of the formation of persistent intermediates. The ozone consumption was consistent with ηDOC. The ratio of ozone consumption to ozone applied decreased from 14 to 12% when ηDOC < 40% because the decolorization in the early stage of the ozonation of AO6 may consume a relatively large amount of ozone. It was found that NO2, NO, CO2, and small amount of SO2 was detected in the off-gas. The effective concentration (EC50) increased from 23.48% to 100%, suggesting that the toxic reduction was achieved, and O3/UV system was superior to O3 alone system

Evaluation of Decolorization, Mineralization, and Toxicity Reduction of an Azo Dye C.I. Reactive Black 5 in a Countercurrent Bubble Column by Ozone

A countercurrent and continuous-flow design bubble column reactor (BCR) was used to investigate variations in traditional parameters of water-containing Reactive Black 5 (RB5) under different gas/liquid flow rates. RB5 is a long-chain diazo dye with a high molecular weight that is widely applied in industry. The results revealed that the variations were functions of the flow rates of the liquid and/or gas and of operation column height. Pseudo-first-order or global-second-order reaction types were used to describe the variations, and the monitored parameters i.e., total organic carbon (TOC), sulfate, and nitrate. Not only did flow patterns affect the RB5 removal and the mineralization of derivatives, but column height might also have had an influence on ozone consumption. It was observed that the extent of decolorization and mineralization decreased as the sampling port height increased, indicating that the column height may reflect the retention time of ozone gas and the contacting time between ozone and...

Activated carbon adsorption, activated sludge and ozonation treatments evaluated by impact intensity based on acute toxicity test

A Toxicity Reduction Evaluation (TRE) conducted on various water treatments was successful in optimizing the acute toxicity of the final effluent. In particular, we found that the acute toxicity of the sample water treated by a water treatment process should not be correlated with the concentrations of the parent compounds still remaining in the water. Therefore, it was concluded that an acute toxicity test based on a bioassay must be performed in order to evaluate the efficiency of the water treatment process for various effluents containing environmental pollutants. In addition, the treatability and the resultant toxicity was evaluated as a simple scoring system. The scoring system ranked the treated water in three classes of toxicity with the calculation of several factors for the concerned toxicity. Using an impact evaluation based on the score of the characteristics, different water treatment processes could be directly compared. The new methodology presented here is specifically effective in listing possible unit operations for a water treatment process based on the impact, and thereby enables targeted and cost-effective water treatment.

Toxicity reduction evaluation, toxicity identification evaluation and toxicity tracking in direct toxicity assessment.

Toxicity reduction evaluations (TREs) in the River Esk and Lower Tees Estuary were based on the approach described by USEPA, but adapted to tackle the specific problems of the two sites. A combination of toxicity tracking and toxicity identification evaluation (TIE) was used at both locations to enhance the understanding of source and type of toxicants present. The assessment of toxicity at Langholm focussed on pesticides present in the sewerage network. The TIE programme indicated that the most likely toxic agents within the effluent were the organophosphate pesticides diazinon and to lesser extent propetamphos, although these did not account for all of the observed toxicity. The exact source of these toxicants was not clear although toxicity tracking identified two potential candidates. The TRE undertaken on the discharge to the lower Tees utilised high-throughput methods with standard test organisms to generate toxicity information throughout a complex sewerage network. The toxicity tracking information was used in conjunction with TIEs to identify a number of key sources of toxicity. Substantial toxicity was associated with a currently untreated industrial effluent. Chemical analysis and TIE highlighted cyanide as the likely toxicant in this effluent and its possible significance in the final discharge.

Evaluation of toxicity reduction of sodium dodecyl sulfate submitted to electron beam radiation

Surfactants, as detergent active substances, are an important source of pollution causing biological adverse effects to aquatic organisms. Several data have been showing ecological disturbance due to the high concentration of surfactants on receiving waters and on wastewater treatment plants. Ionizing radiation has been proved as an effective technology to decompose organic substances and few papers have included ecotoxicological aspects. This paper shows the reduction of acute toxicity of a specific surfactant, sodium dodecyl sulfate (SDS), when diluted in distilled water and submitted to electron beam radiation. The study included two test-organisms, the marine bacteria Vibrio fischeri and the crustacean Daphnia similis. Radiation processing resulted in an important acute toxicity removal for both assays, which can be summarized between 70% and 96%, using 3.0, 6.0, 9.0 and 12.0 kGy as radiation doses. Nevertheless, lower doses demonstrated better effect than 9.0 and 12.0 kGy and the bacterium assay was more sensitive to SDS than crustacean assay.

On line biomonitors used as a tool for toxicity reduction evaluation of in situ groundwater remediation techniques

Success of groundwater remediation is typically controlled via snapshot analysis of selected chemical substances or physical parameters. Biological parameters, i.e. ecotoxicological assays, are rarely employed. Hence the aim of the study was to develop a bioassay tool, which allows an on line monitoring of contaminated groundwater, as well as a toxicity reduction evaluation (TRE) of different remediation techniques in parallel and may furthermore be used as an additional tool for process control to supervise remediation techniques in a real time mode. Parallel testing of groundwater remediation techniques was accomplished for short and long time periods, by using the energy dependent luminescence of the bacterium Vibrio fischeri as biological monitoring parameter. One data point every hour for each remediation technique was generated by an automated biomonitor. The bacteria proved to be highly sensitive to the contaminated groundwater and the biomonitor showed a long standing time despite the highly corrosive groundwater present in Bitterfeld, Germany. The bacterial biomonitor is demonstrated to be a valuable tool for remediation success evaluation. Dose response relationships were generated for the six quantitatively dominant groundwater contaminants (2-chlortoluene, 1,2- and 1,4-dichlorobenzene, monochlorobenzene, ethylenbenzene and benzene). The concentrations of individual volatile organic chemicals (VOCs) could not explain the observed effects in the bacteria. An expected mixture toxicity was calculated for the six components using the concept of concentration addition. The calculated EC 50 for the mixture was still one order of magnitude lower than the observed EC 50 of the actual groundwater. The results pointed out that chemical analysis of the six most quantitative substances alone was not able to explain the effects observed with the bacteria. Thus chemical analysis alone may not be an adequate tool for remediation success evaluation in terms of toxicity reduction.

The Evaluation of Pulp and Paper Mill Effluents Using Biological Assessment

The effect of pulp and paper mill effluents on the environment should be understood accurately, because the quantity of water discharged from a mill is very large. Current effluent regulations are based on biological oxygen demand (BOD) or chemical oxygen demand (COD), but these measures do not reflect the actual environmental effect of effluent.Bioassay are already used to determine the effect of effluent discharge on the environment in several foreign countries, and even in Japan it is expected that a bioassay will be introduced in the future. The type of bioassay used in nearly every country is the sublethal toxicity test, using fish, water frea, or green algae, although test conditions are slightly different in each country.The bioassay is not only for effluent monitaring ; it is also an effective procedure for toxicity identification evaluation (TIE) and toxicity reduction evaluation (TRE). By using TRE method, we would be able to further decrease the environmental effect. Although a total effluent free (TEF) system is the ideal, that is difficult to realize right away.We should aim at sustainable development while balancing considerations of risk and benefit.

Cultured human-cell-based bioassay for environmental risk management.

Among bioassays for evaluating various impacts of chemicals on humans and ecosystems, those based on cultured mammalian-cells can best predict acute lethal toxicity to humans. We expect them to be employed in the future in environmental risk management alongside mutagenicity tests and endocrine-disrupting activity tests. We recently developed a disposable bioassay device that immobilizes human hepatocarcinoma cells in a small micropipette tip. This enables very quick (within 2 h) evaluation of acute lethal toxicity to humans. For bioassay-based environmental management, 2 promising approaches have been demonstrated by the US-EPA: toxicity identification evaluation (TIE) and toxicity reduction evaluation (TRE). The Japanese Ministry of Environment has been supporting a multi-center validation project, aimed at assembling a bioassay database. To make full use of these resources, we present a numerical model that describes contribution of individual chemical to observed toxicity. This will allow the selection of the most effective countermeasure to reduce the toxicity. Bioassay-based environmental risk management works retrospectively, whereas impact assessment using substance flow models and toxicity databases works prospective. We expect that these 2 approaches will exchange information, act complementarily, and work effectively in keeping our environment healthy in the 21 st century.