Toxicity identification in metal plating effluent: implications in establishing effluent discharge limits using bioassays in Korea

Effect of low-purity Fenton reagents on toxicity of textile dyeing effluent to Daphnia magna

This study aimed to identify the source of toxicity in textile dyeing effluent collected from February to July 2016, using Daphnia magna as a test organism. Toxicity identification evaluation (TIE) procedures were used to identify the toxicants in textile dyeing effluent, and Jar testing to simulate the Fenton process was conducted to identify the source of toxicants. Textile dyeing effluent was acutely toxic to D. magna [from 1.5 to 9.7 toxic units (TU)] during the study period. TIE results showed that Zn derived from the Fenton process was a key toxicant in textile dyeing effluent. Additionally, Jar testing revealed that low-purity Fenton reagents (FeCl₂ and FeSO₄), which contained large amounts of Zn (89 838 and 610 mg L^-1, respectively), were the source of toxicity. Although we were unable to conclusively identify the residual toxicity (approx. 1.4 TU of 9.71 TU) attributable to unknown toxicants in textile dyeing effluent, the findings of this study suggest that careful operation of the Fenton treatment process could contribute to eliminating its unintended toxic effects on aquatic organisms.

In vitro and in vivo investigation of the genotoxic potential of waters from rivers under the influence of a petroleum refinery (São Paulo State - Brazil)

In recent years concern about the chemical composition of wastewater generated by the oil refining industry has increased, even after its treatment. These wastewaters contain substances that can harm both the entire aquatic ecosystem and the health of any exposed organisms. The aim of this study was to evaluate the genotoxic and mutagenic potentials of the effluent generated by the largest Brazilian petroleum refinery, the effectiveness of the treatments used by the refinery, and whether its effluent can compromise the water quality of the river where it is discarded. Chromosomal aberration and micronucleus assays were performed in Allium cepa and micronucleus test in mammalian cell culture (CHO-K1). The samples were collected in three sites at the refinery: one site on the Jaguari River and two sites on the Atibaia Rivers (upstream and downstream of the discharged effluent), under three different climatic conditions. Tests with A. cepa showed increased frequencies of chromosomal aberrations and micronuclei in meristematic cells for the effluent after physico-chemical treatment, but the samples after treatment biological and stabilization pond presented none of these abnormalities. It was observed that the induced damage in the meristematic cells was not observed in the F₁ cells of A. cepa roots. The micronucleus test performed with mammalian cell culture also indicated that the effluent, after physico-chemical treatment, induced a significant increase in micronucleus frequencies. Plant and hamster cells exposed to the other samples collected inside the refinery and in the Jaguari and Atibaia Rivers did not present evidence of genotoxicity and mutagenicity in the tests performed. This study showed that the effluent treated carried out by the refinery (biological treatment followed by a stabilization pond) proved to be efficient for the removal of the toxic load still present after the physico-chemical treatment, since no change in the quality of the Atibaia River was observed. However, because this is an industry with a high production of effluent with toxic potential, its effluents must be constantly monitored, so that there is no compromise of the water quality of the receiving river.

Assessment of genotoxic, mutagenic, and recombinogenic potential of water resources in the Paranaíba River basin of Brazil: A case study

Exposure to certain pollutants induces a series of alterations in deoxyribonucleic acid (DNA) that may result in genotoxic/mutagenic effects in exposed individuals. The present study aimed to monitor genotoxic, mutagenic, and recombinogenic potential and consequently water quality in two streams in the Paranaíba River basin in the state of Minas Gerais, Brazil, using two bioindicator fish (Rhamdia quelen and Geophagus brasiliensis). The micronucleus (MN) test and somatic recombination and mutation test (SMART) were employed to assess DNA damage. The water quality index (WQI) at the reference site control (S1) due to its proximity to the river source was compared to Córrego do Óleo (S2) with respect to chemical parameter levels of biochemical oxygen demand (BOD), dissolved-oxygen rates (DO), and total solid and fecal coliform counts. These chemical parameters were above the permitted limits at Córrego do Óleo (S2). At a third site, Córrego Liso (S3), a poor WQI was detected, attributed to the influence of domestic and industrial activities where BOD, DO, total solid, fecal coliform, total phosphorus, and turbidity rates exceeded premissible limits. The MN frequencies and the numbers of MN per cell (CMN) at sites S2 and S3 were significantly higher than those at S1 in both species. It is of interest that the increased frequency of MN was similar to the positive control cyclophosphamide only at S3, suggesting that the effects of water contaminants were most severe at this site. At sites assessed (S2 and S3), there was a significant rise in somatic mutation and recombination in the wings of Drosophila melanogaster, indicating the presence of trace elements, mainly lead (Pb) and cadmium (Cd), in the effluents in the Paranaíba River basin sites.

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.

Multispecies acute toxicity evaluation of wastewaters from different treatment stages in a coking wastewater-treatment plant

Coking wastewater contributes approximately 5% of the total discharge volume of industrial wastewaters every year in China. The toxicity of coking wastewater to aquatic organisms is still unknown. The authors evaluated the toxicity of wastewater from different treatment stages in a coking wastewater treatment plant, South China, using 5 test species belonging to different trophic levels: luminous bacteria, green alga, a crustacean, duckweed, and zebrafish embryos. The raw influent displayed the highest toxicity to the test species, with toxic units ranging from 16.2 to 1176. The toxicity in the wastewater was then gradually removed by sequential primary treatment, biological fluidized-bed treatment, and secondary clarifier treatment. The toxic unit of the final effluent was reduced to 2.26 for the green alga (Pseudokirchneriella subcapitata) and to 0 for the other 4 organisms. Quantitative analysis of metals and polycyclic aromatic hydrocarbons (PAHs) and qualitative scanning by gas chromatography-mass spectrometry showed the presence of a variety of pollutants in the coking wastewaters. Multivariate statistical analysis revealed that the toxicity in the coking wastewater was correlated to the chemical oxygen demand, total nitrogen, ammonia nitrogen, volatile phenols, sulfide, metals (Cr, As, Sb, Hg, Pb, and Ni), and ΣPAHs. Based on the results, it is required to set a safety emission limit value for the discharge of coking wastewater to protect aquatic organisms in the receiving water bodies.

Identification of toxicity variations in a stream affected by industrial effluents using Daphnia magna and Ulva pertusa

A comprehensive toxicity monitoring study from August to October 2011 using Daphnia magna and Ulva pertusa was conducted to identify the cause of toxicity in a stream receiving industrial effluents (IEs) from a textile and leather products manufacturing complex. Acute toxicity toward both species was observed consistently in IE, which influenced toxicity of downstream (DS) water. A toxicity identification evaluation (TIE) confirmed that both Cu and Zn were key toxicants in the IE, and that the calculated toxicity based on Cu and Zn concentrations well simulated the variation in the observed toxicity (r(2)=0.9216 and 0.7256 for D. magna and U. pertusa, respectively). In particular, U. pertusa was sensitive enough to detect acute toxicity in DS and was useful to identify Zn as a key toxicant. Activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and malondialdehyde were induced significantly in D. magna, although acute toxicity was not observed. In addition, higher levels of antioxidant enzymes were expressed in DS than upstream waters, likely due to the Cu and Zn from IE. Overall, TIE procedures with a battery of bioassays were effective for identifying the cause of lethal and sub-lethal toxicity in effluent and stream water.

Use of TIE techniques to characterize industrial effluents in the Pearl River Delta region

We investigated the acute toxicity of various industrial effluents in the Pearl River Delta region using lux bacteria, duckweed, green algae, crustaceans and zebrafish. The potential toxicants in the industrial effluents were identified and evaluated by lux bacteria bioassay and chemical analysis. The results show that green algae (Pseudokirchneriella subcapitata) and crustacean (Ceriodaphnia dubia) were more sensitive to the effluents from electronic and electroplate factories than other test species, while lux bacteria were more sensitive to all the other effluents. The toxicities of effluents from electronic and electroplate factories to the six test organisms were significantly higher than those of the other industrial effluents, and mainly caused by metals. Noticeably, organic pollutants were the main contributing factor to the toxicity of effluents from textile and dyeing plants, pulp and paper mills, fine chemical factories and municipal wastewater treatment plants.

Assessing acute toxicity of effluent from a textile industry and nearby river waters using sulfur-oxidizing bacteria in continuous mode

Bioassays are becoming an important tool for assessing the toxicity of complex mixtures of substances in aquatic environments in which Daphnia magna is routinely used as a test organism. Bioassays outweigh physicochemical analyses and are valuable in the decision-making process pertaining to the final discharge of effluents from wastewater treatment plants as they measure the total effect of the discharge which is ecologically relevant. In this study, the aquatic toxicity of a textile plant effluent and river water downstream from the plant were evaluated with sulfur-oxidizing bacterial biosensors in continuous mode. Collected samples were analysed for different physicochemical parameters and 1,4-dioxane was detected in the effluent. The effluent contained a relatively high chemical oxygen demand of 60 mg L(-1), which exceeded the limit set by the Korean government for industrial effluent discharges. Results showed that both the effluent and river waters were toxic to sulfur-oxidizing bacteria. These results show the importance of incorporating bioassays to detect toxicity in wastewater effluents for the sustainable management of water resources.

A comparative study on toxicity identification of industrial effluents using Daphnia magna

In this study, acute toxicity monitoring and toxicity identification evaluation procedures were applied to identify causative toxicants in industrial effluents. Effluents from a metal plating factory and a rubber products factory were acutely toxic toward Daphnia magna and the toxicity varied over different sampling events (2.9-5.9 and 1.7-7.6 TU, respectively). For the rubber products effluent, it was confirmed that zinc (5.65-13.18 mg L(-1)) was found to be a major cause of toxicity, which is likely originated from zinc 2-mercaptobenzothiazole and zinc diethyldithiocarbamate used as vulcanization accelerators. For the metal plating effluent, it appeared that the presence of high concentrations of Cl(-) and SO(4)(2-) (8,539-11,400 and 3,588-4,850 mg L(-1), respectively) caused the observed toxicity. These toxicants likely originated from sodium bisulfate (NaHSO(3)) and sodium hypochlorite (NaOCl) used as reducing and oxidizing agents. Though copper was found to be present in levels much higher than the EC(50) (50% effective concentration) value, this was not attributable to the toxicity of metal plating effluent likely due to complexation with dissolved organic matter.

A comparative study of toxicity identification using Daphnia magna and Tigriopus japonicus: implications of establishing effluent discharge limits in Korea

In Korea, the new permission criteria for industrial effluents based on Daphnia magna acute toxicity tests will be gradually implemented starting from 2011. Thus, in this study, toxicity assessment and identification using a marine species (Tigriopus japonicus) and the freshwater species (D. magna) was comparatively investigated. Effluent from an acid mine drainage treatment plant showed acute toxicity toward both organisms due to low pH, which was removed by neutralization of the effluent. Additionally, evaluation of the effluent of an electronics company revealed that Cu was attributable to the observed toxicity, and the effluent was more toxic toward T. japonicus than D. magna. Moreover, effluents from a metal plating factory were acutely toxic toward D. magna (6.50 TU), while they were not toxic against T. japonicus. Toxicity identification revealed that the high level of Cl- (12,841 mg L(-1)) was the cause of toxicity. Thus, the effluents had no effect on the marine species, T. japonicus. These findings suggest that a marine species rather than a freshwater species is more desirable for toxicity assessment of industrial effluent discharged into the saltwater, and thus should be considered in the legislation of toxicity-based discharge limits in Korea.

Long-term evaluation of lethal and sublethal toxicity of industrial effluents using Daphnia magna and Moina macrocopa

Acute toxicity and feeding rate inhibition of effluent from a wastewater treatment plant and its adjacent stream water on Daphnia magna and Moina macrocopa were comparatively studied. The acute toxicity of the final effluent (FE) fluctuated greatly over the sampling period from January to August 2009. Toxicity identification results of the FE in July 2009 showed that Cu originating from the Fenton's reagent was likely a key toxicant. In addition, the feeding rate of both species was still inhibited by the FEs in which acute toxicity was not observed. These findings indicate that the feeding response would be a useful tool for monitoring sublethal effects of industrial effluents. For the acute toxicity test, M. macrocopa was more sensitive than D. magna, but the opposite result was true in the case of the feeding rate inhibition. These suggest that different species have different sensitivities to toxic chemicals and to the test methods.

The relationship between whole effluent toxicity (WET) and chemical-based effluent quality assessment in Vojvodina (Serbia)

The relationship between whole effluent toxicity (WET) and chemical-based effluent quality assessment across a range of effluent types was examined for the first time in Serbia. WET was determined by Daphnia magna acute tests, while chemical-based toxicity was taken as theoretical for concentrations of priority chemicals and effluent quality assessment based on the valid Serbian regulations. A poor correlation was found between WET and chemical-based effluent quality assessment: positive toxicity tests were found, in general, in cases where samples satisfied the requirements of mandatory effluent monitoring. Statistically insignificant correlation between the predicted and observed toxicity indicated that the presence of priority substances accounted to the overall toxicity only to a certain degree, most probably due to a rather short list of priority pollutants regularly analysed in effluents. Current monitoring requirements neglect hazards that derive from potentially present toxicants and unpredictable toxicity of complex mixtures, which led to poor correlation between the WET and chemical-based results in this study.

A toxicity monitoring study on identification and reduction of toxicants from a wastewater treatment plant

In this study, toxicity of effluents in a wastewater treatment plant and of receiving water in an adjacent stream was periodically monitored from November 2007 to June 2008, in order to trace and reduce sources of toxicants. The results showed that toxicity of final effluent (FE) changed greatly over different sampling events, and appeared to have impacts on toxicity of downstream water with a significant correlation (r(2)=0.87, p<0.05). In particular, FE toxicity was always higher than that of secondary effluent (SE). Toxicity identification evaluation (TIE) for the FE sample collected in March 2008 showed that FE toxicity was attributed to low quality of Fenton reagent with Zn contamination used for SE treatment. Furthermore, Zn concentrations in FE samples significantly correlated with FE toxicity during the sampling period (r(2)=0.95, p<0.05). After changing the Fenton reagent to one containing low Zn, Zn concentration and toxicity of FE greatly decreased in the following months.

Quantification of differentially expressed genes in Daphnia magna exposed to rubber wastewater

In this study, differentially expressed genes (DEGs) were investigated in Daphnia magna exposed to rubber wastewater using an annealing control primer (ACP)-based polymerase chain reaction (PCR) and real-time PCR. Among three identified DEGs, two genes (DEG1 and DEG2) were up-regulated, and DEG1 expression was well-correlated to a logarithm of rubber wastewater concentration (r2=0.971, p<0.0001). In addition, DEG1 expression in D. magna exposed to rubber wastewater was strongly correlated with that of D. magna exposed to Zn (r2=0.9513, p<0.05), suggesting that the induction of DEG1 was caused by Zn, which is the dominant toxicant in rubber wastewater. In addition, DEG1 expression was more sensitive to toxicants than immobility, which is the conventional endpoint in toxicity tests using D. magna. The lowest observed effect concentrations (LOEC) determined using immobility tests were 2.5% for rubber wastewater and 1.6mgl(-1) for Zn. In contrast, a significant increase in DEG1 expression was observed at exposure concentrations of as low as 0.6% rubber wastewater and 0.2mgl(-1) Zn. These results indicate that DEG1 is a sensitive and quantitative biomarker of water and wastewater containing Zn.