Effect of Chronic Exposure to Textile Wastewater Treatment Plant Effluents on Growth Performance, Oxidative Stress, and Intestinal Microbiota in Adult Zebrafish (Danio rerio)

The ever-increasing production and processing of textiles will lead to greater risks of releasing pollutants into the environment. Textile wastewater treatment plants (TWTPs) effluent are an important source of persistent toxic pollutants in receiving water bodies. The effects of specific pollutants on organisms are usually studied under laboratory conditions, and therefore, comprehensive results are not obtained regarding the chronic combined effects of pollutants under aquatic environmental conditions. Thus, this study aimed to determine the combined effects of TWTP effluents on the growth performance, oxidative stress, inflammatory response, and intestinal microbiota of adult zebrafish (Danio rerio). Exposure to TWTP effluents significantly inhibited growth, exacerbated the condition factor, and increased the mortality of adult zebrafish. Moreover, markedly decreases were observed in the activities of antioxidant enzymes, such as CAT, GSH, GSH-Px, MDA, SOD, and T-AOC, mostly in the intestine and muscle tissues of zebrafish after 1 and 4 months of exposure. In addition, the results demonstrated that TWTP effluent exposure affected the intestinal microbial community composition and decreased community diversity. Slight changes were found in the relative abundance of probiotic Lactobacillus, Akkermansia, and Lactococcus in zebrafish guts after chronic TWTP effluent exposure. The chronic toxic effects of slight increases in opportunistic pathogens, such as Mycoplasma, Stenotrophomonas, and Vibrio, deserve further attention. Our results reveal that TWTP effluent exposure poses potential health risks to aquatic organisms through growth inhibition, oxidative stress impairment of the intestine and muscles, and intestinal microbial community alterations.

OIL EFFLUENT EXPOSURE INDUCED BIOCHEMICAL MODULATIONS IN SUBCELLULAR / TISSUES (CYTOSOL,MICROSOMES) OF FOOT, GILL AND DIGESTIVE GLANDS OF LAMELLIDENS MARGINALIS.

Sub-cellular fractions (cytosolic and microsomal) were prepared from the tissues (foot, gill and digestive gland) of freshwater mussel Lamellidens marginalis and were scrutinized to investigate the modulation of biochemical components (protein, carbohydrate and lipids) after exposure of sub-lethal concentrations of 1/4th (11.88 ppt) and 1/10th (8.55 ppt) of 96-hr LC 50 of oil effluent, and recovery period (depuration-without oil effluent) after seven days interval i.e., 1st, 8th, 15th 22nd and 30th days. At the end of 30th day, biochemical components in both exposure and depuration periods, were analysed from the tissues of mussels. The accumulation of oil effluent in the tissues gradually increased, when exposed to both sub-lethal concentrations of oil effluent and significantly and gradually decreased levels of protein, carbohydrate and lipid contents in the sub-cellular tissues of mussels were observed. During recovery period (without adding oil effluent), all depleted biochemical contents were recovered, increased, gradually, significantly from 30th day to Ist day (P<0.05) and one-way ANOVA showed progressive positive regression coefficient values (P<0.05) in all days. The enhanced and recovered levels of biochemical components in oil-exposed mussels demonstrate a well-established defense mechanism in mollusc, and this response offers the possibility of use as a biomarker for the early detection of oil pollution.

Utility of a multi-tracer approach as a component of adaptive monitoring for municipal wastewater impacts

Distinguishing municipal wastewater effluent (MWWE) from other industrial effluents or through an urbanized watershed can be challenging. In complex receiving environments, linking environmental responses to specific compounds or effluents is not always straight forward. In order to characterize the inherent complexity of tracing MWWE in aquatic systems influenced by multiple stressors, a proposed multi-tracer suite is intended to highlight areas of potential biological concern. Characterization and quantification of effluent exposure to aquatic biota in this manner is essential to shape policies intended to encourage wastewater infrastructure development (i.e. treatment plant upgrade) and broader environmental management. This paper describes the use of a comprehensive suite of tracers that includes isotopes in support of a core surveillance program, demonstrating its effectiveness both empirically and with respect to diagnostic value contributed to monitoring programs.

Novel metabolomic method to assess the effect-based removal efficiency of advanced wastewater treatment techniques

Environmental contextAdvanced wastewater treatment is required to remove pharmaceuticals and many other consumer chemicals from wastewater effluent. There are conflicting findings, however, on the toxicity of treated effluent, and its effect on living organisms is often neglected. We show that the effect-based removal efficiency of wastewater treatment technologies can be assessed by metabolomic methods, and that this approach contributes to a safer and more controlled water quality. AbstractThere are conflicting findings on the toxicity of effluent from wastewater treatment plants, and only limited possibilities for assessing the effect-based removal efficiency (EBRE) of different treatment techniques. We describe a metabolomics approach to detect perturbations in fatty acid catabolic pathways as a proxy for biological effects. Metabolites in three fatty acid pathways were analysed in a common damselfly larva (Coenagrion hastulatum) by liquid chromatography coupled to mass spectrometry. The larvae were exposed for one week to either conventionally treated effluent (activated sludge treatment), effluent additionally treated with ozone, or effluent additionally treated with biochar filtration, and results were compared with those from tap water control exposure. Five lipoxygenase-derived oxylipins (9,10,13-TriHOME, 9,12,13-TriHOME, 9-HODE, 9-HOTrE, and 13-HOTrE) decreased in response to conventionally treated effluent exposure. By using an additional treatment step, oxylipin levels were restored with exception of 9,10,13-TriHOME (ozonated effluent), and 9-HOTrE and 13-HOTrE (effluent filtered with biochar). Thus, exposure to wastewater effluent affected fatty acid metabolite levels in damselfly larvae, and a subset of the analysed metabolites may serve as indicators for biological effects in biota in response to effluent exposure. To that effect, our findings suggest a new metabolomics protocol for assessing EBRE.

Tannery effluent effect on the haematological parameters of freshwater fish, Channa punctatus

The present investigation was undertaken to evaluate the tannery effluent toxicity stress symptoms in fish blood during a long term of exposure period. The effect of tannery effluent on various haematological parameters were evaluated exposing fresh water fish, C. punctatus to different concentration i.e., [Control, 5% Tannery effluent (TE), 10% TE and 20% TE] of tannery effluent. Exposed of fish to tannery effluent showed a significant decrease in the haemoglobin (Hb) content (9.16± 0.08), red blood cells (3.32 ± 0.12), packed cell volume (34.66 ± 0.33) and mean corpuscular haemoglobin (MCH) values, whereas significant increase in the white blood cells (WBC), erythro-cyte sedimentation rate (ESR) and clotting time was recorded with increase in exposure periods as compared to control respectively. Hb, RBC and MCHC values showed fluctuating results. The haematological parameters were decreases from 15th days of exposure periods to 45th days of exposure period. The decrease in haematological parameters clearly indicates that the exposed fishes have become anemic due to tannery effluent exposure.