Microbial Degradation and Detoxification of Synthetic Dye Mixture by Pseudomonas sp. SUK 1

Plant and yeast consortium for efficient remediation of dyes and effluents: a biochemical and toxicological study

Textile effluent carries a range of dyes that may be recalcitrant and resistant to biodegradation. A unique consortium of the Fimbristylis dichotoma and Saccharomyces cerevisiae is exploited for the biodegradation of an azo dye Rubine GFL and actual textile effluent. This consortium enhances the rate of biodegradation of Rubine GFL and actual textile effluent with an excellent rate of biodegradation of 92% for Rubine GFL and 68% for actual textile effluent when compared to the individual one within 96 h. Speedy decolorization of Rubine GFL and actual textile effluent was observed due to the induction of oxido-reductive enzymes of the FD-SC consortium. Along with the significant reduction in the values of COD, BOD, ADMI, TSS, and TDS with 70, 64, 65, 41, and 52%, respectively, in experimental sets treated with FD-SC consortium. The biodegradation of Rubine GFL was confirmed with UV-Vis spectroscopy at the preliminary level, and then, metabolites formed after degradation were detected and identified by FTIR, HPLC, and GC-MS techniques. Also, decolorization of the dye was observed in the sections of the root cortex of Fimbristylis dichotoma. The toxicity of dye and metabolites formed after degradation was assessed by seed germination and bacterial count assay, where increased germination % and bacterial count from 31×107CFUs to 92 × 107 CFUs reflect the nontoxic nature of metabolites. Furthermore, the nontoxic nature of metabolites was confirmed by fish toxicity on Cirrhinus mrigala showed normal structures of fish gills and liver in the groups treated with FD-SC consortium proving the better tactic for biodegradation of dyes and textile effluent.

Chronic industrial perturbation and seasonal change induces shift in the bacterial community from gammaproteobacteria to betaproteobacteria having catabolic potential for aromatic compounds at Amlakhadi canal

Escalating proportions of industrially contaminated sites are one of the major catastrophes faced at the present time due to the industrial revolution. The difficulties associated with culturing the microbes, has been circumvent by the direct use of metagenomic analysis of various complex niches. In this study, a metagenomic approach using next generation sequencing technologies was applied to exemplify the taxonomic abundance and metabolic potential of the microbial community residing in Amlakhadi canal, Ankleshwar at two different seasons. All the metagenomes revealed a predominance of Proteobacteria phylum. However, difference was observed within class level where Gammaproteobacteria was relatively high in polluted metagenome in Summer while in Monsoon the abundance shifted to Betaproteobacteria. Similarly, significant statistical differences were obtained while comparing the genera amongst contaminated sites where Serratia, Achromobacter, Stenotrophomonas and Pseudomonas were abundant in summer season and the dominance changed to Thiobacillus, Thauera, Acidovorax, Nitrosomonas, Sulfuricurvum, Novosphingobium, Hyphomonas and Geobacter in monsoon. Further upon functional characterization, the microbiomes revealed the diverse survival mechanisms, in response to the prevailing ecological conditions (such as degradation of aromatic compounds, heavy metal resistance, oxidative stress responses and multidrug resistance efflux pumps, etc.). The results have important implications in understanding and predicting the impacts of human-induced activities on microbial communities inhabiting natural niche and their responses in coping with the fluctuating pollution load.

Purposely Development of the Adaptive Potential of Activated Sludge from Municipal Wastewater Treatment Plant Focused on the Treatment of Landfill Leachate

Biological treatment is a key technology in landfill leachate treatment However, often its efficiency is not high enough due to the pollutants in concentrations above the critical ones. The present study aimed to investigate the adaptive responses that occur in activated sludge (AS) during landfill leachate purification. A model process with AS from a municipal wastewater treatment plant and landfill leachate in increasing concentrations was constructed. The data showed that when dilutions 25 and 50 times had been applied the structure of the AS was preserved, but the COD cannot be reduced below 209 mg O2/L. The feed of undiluted leachate destroyed the AS structure as SVI was reduced to 1 mL/g, biotic index to 1, floc size was greatly reduced and COD remained high (2526 mg O2/L). The dominant group of protozoa was changed from attached to free-swimming ciliates. An increase of the bacterial groups responsible for the xenobiotics elimination (aerobic heterotrophs, genera Pseudomonas, Acinetobacter, Azoarcus, Thauera, Alcaligenes) was registered. This was accompanied by a significant increase in free bacteria. The obtained data showed that for optimal treatment of this type of water it is necessary to include a combination of biological treatment with another non-biological method (membrane filtration, reverse osmosis, etc.).

Synergistic effect of biological and advanced oxidation process treatment in the biodegradation of Remazol yellow RR dye

The current study investigated the efficiency of synergistic biological and Advanced Oxidation Process (AOPs) treatment (B-AOPs) using Aeromonas hydrophila SK16 and AOPs-H2O2 in the removal of Remazol Yellow RR dye. Singly, A. hydrophila and AOPs showed 90 and 63.07% decolourization of Remazol Yellow RR dye (100 mg L-1) at pH 6 and ambient temperature within 9 h respectively. However, the synergistic B-AOPs treatments showed maximum decolorization of Remazol Yellow RR dye within 4 h. Furthermore, the synergistic treatment significantly reduced BOD and COD of the textile wastewater by 84.88 and 82.76% respectively. Increased levels in laccase, tyrosinase, veratryl alcohol oxidase, lignin peroxidase and azo reductase activities further affirmed the role played by enzymes during degradation of the dye. UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) and gas chromatography-mass spectroscopy (GC-MS) confirmed the biotransformation of dye. A metabolic pathway was proposed based on enzyme activities and metabolites obtained after GC-MS analysis. Therefore, this study affirmed the efficiency of combined biological and AOPs in the treatment of dyes and textile wastewaters in comparison with other methods.

Chloride or sulfate? Consequences for ozonation of textile wastewater

Ozonation of chloride-rich textile wastewater is a common pretreatment practice in order to increase biodegradability and therefore meet the discharge limits. This study is the first to investigate ozone-chloride/bromide interactions and formation of hazardous adsorbable organic halogens (AOX) in real textile wastewater. Initially effect of ozonation on chloride-rich real textile wastewater samples were investigated for adsorbable organic halogens (AOX) formation, biodegradability and toxicity. After 15 min of ozonation, maximum levels of chlorine/bromine generation (0.3 mg/l) and AOX formation (399 mg/l) were reached. OUR and SOUR levels both increased by approximately 58%. Daphnia magna toxicity peaked at 100% for 10 min ozonated sample. Considering adverse effects of ozonation on chloride-rich textile industry effluents, we proposed replacement of NaCl with Na₂SO₄. Comparative ozonation experiments were carried out for both chloride and sulfate containing synthetic dyeing wastewater samples. Results showed that use of sulfate in reactive dyeing increased biodegradability and decreased acute toxicity. Although sulfate is preferred over chloride for more effective dyeing performance, the switch has been hampered due to sodium sulfate's higher unit cost. However, consideration of indirect costs such as contributions to biodegradability, toxicity, water and salt recovery shall facilitate textile industry's switch from chloride to sulfate.