The presence of both organic and inorganic pollutants in water due to industrial, agricultural, and domestic activities has led to the global need for the development of new, improved, and advanced but effective technologies to effectively address the challenges of water quality. It is therefore necessary to develop a technology which would completely remove contaminants from contaminated waters. TiO2 (titania) nanocatalysts have a proven potential to treat "difficult-to-remove" contaminants and thus are expected to play an important role in the remediation of environmental and pollution challenges. Titania nanoparticles are intended to be both supplementary and complementary to the present water-treatment technologies through the destruction or transformation of hazardous chemical wastes to innocuous end-products, that is, CO2 and H2O. This paper therefore explores and summarizes recent efforts in the area of titania nanoparticle synthesis, modifications, and application of titania nanoparticles for water treatment purposes.

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Recent developments in environmental photocatalytic degradation of organic pollutants: the case of titanium dioxide nanoparticles—a review

Water pollution caused by the discharge of hazardous textile effluents is a serious environmental problem worldwide. In order to assess the pollution level of the textile effluents, various physico-chemical parameters were analyzed in the textile wastewater and agricultural soil irrigated with the wastewater (contaminated soil) using atomic absorption spectrophotometer and gas chromatography-mass spectrometry (GC-MS) analysis that demonstrated the presence of several toxic heavy metals (Ni, Cu, Cr, Pb, Cd, and Zn) and a large number of organic compounds. Further, in order to get a comprehensive idea about the toxicity exerted by the textile effluent, mung bean seed germination test was performed that indicated the reduction in percent seed germination and radicle-plumule growth. The culturable microbial populations were also enumerated and found to be significantly lower in the wastewater and contaminated soil than the ground water irrigated soil, thus indicating the biotic homogenization of indigenous microflora. Therefore, the study was aimed to develop a cost effective and ecofriendly method of textile waste treatment using native soil bacterium, identified as Arthrobacter soli BS5 by 16S rDNA sequencing that showed remarkable ability to degrade a textile dye reactive black 5 with maximum degradation of 98% at 37 °C and pH in the range of 5–9 after 120 h of incubation.

Toxicity evaluation of textile effluents and role of native soil bacterium in biodegradation of a textile dye.

Effluents from the paint industry have been a major source of environmental pollution. There is a need to investigate the compliance of wastewater discharged from paint industries with regulatory standards. In response, this study evaluates the physicochemical parameters of both raw and treated wastewater, the wastewater treatment plants (WWTPs) efficiencies as well as the compliance level of five selected paint manufacturing companies in Lagos, Nigeria with some regulatory standards: Federal Ministry of Environment (FME) in Nigeria, World Health Organization (WHO) and Department of Water Affairs (DWA) in South Africa. All parameters investigated were analysed using standard methods. The values of pH, electrical conductivity (EC) and total dissolved solids (TDS) levels were in the range of 4–12.2, 149.1–881.3 mS/m and 1100–6510 mg/L, respectively. The range of other parameters include total suspended solids (TSS); 0–2470 mg/L, TS; 1920–6510 mg/L, chloride; 63.8–733.8 mg/L, dissolved oxygen (DO); 0–6.7 mg/L, oil and grease (O & G); 44–100 mg/L, biochemical oxygen demand (BOD); 162.8–974.7 mg/L, chemical oxygen demand (COD); 543–1231 mg/L, nitrates;12.89–211.2 mg/L, phosphate; below detection limit (bdl)–0.02 mg/L, sulphate; 195–1434 mg/L, nickel; bdl–1.9 mg/L while copper, lead and chromium were below detection limits. The results indicated that the WWTPs of the studied paint companies were ineffective in reducing the TS, TSS, BOD, COD and (O & G) to acceptable limits. Routine monitoring of wastewater from paint industries is therefore recommended to prevent the risk of contamination to the receiving watershed which many communities rely on as source for domestic water.

Physico-Chemical Analysis of Wastewater Discharge from Selected Paint Industries in Lagos, Nigeria

A bacterial consortium BMP1/SDSC/01 consisting of six isolates was isolated from textile effected soil, sludge, and textile effluent from Hudiara drain near Nishat Mills Limited, Ferozepur Road, Lahore, Pakistan. It was selected because of being capable of degrading and detoxifying red, green, black, and yellow textile dyes. The pH and supplements were optimized to enhance the decolorization ability of the selected consortium. The results indicated that decolorizing ability of consortium for the red, green, black, and yellow dyes was higher as compared to individual strains. The consortium was able to decolorize 84%, 84%, 85%, 85%, and 82% of 200 ppm of red, green, black, yellow, and mixed dyes within 24 h while individual strain required 72 h. On supplementing urea, the consortium decolorized 87, 86, 89, 86, and 83%, respectively, while on supplementing sodium chloride the consortium decolorized 93, 94, 93, 94, and 89% of red, green, black, yellow, and mixed dyes, respectively, which was maximum while in the presence of ascorbic acid and ammonium chloride it showed intermediate results. The effect of untreated and treated dyes was investigated on Zea mays L. (maize) and Sorghum vulgare Pers. (sorghum). This study will help to promote an efficient biotreatment of textile effluents.

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Enhancing the Decolorizing and Degradation Ability of Bacterial Consortium Isolated from Textile Effluent Affected Area and Its Application on Seed Germination

The present study was aimed to evaluate the presence of harmful heavy metals in textile dyes and selected textile effluents. Physicochemical parameters are the significant alarming signs of water pollution. The textile waters analyzed in the study showed elevated TSS, were samples DU1 and DU3 was recorded with 196 mg/L and 584 mg/L, which is considerably high than the permitted limit. The dyes and effluents were characterized by the presence of predominant heavy metals such as cadmium, chromium, lead, arsenic, and zinc. Phytotoxicity analysis indicated all reactive dyes had less significance effect on seed germination and also affects the chlorophyll content which directly signifies the toxic effect of dyes, whereas all four effluents showed restricted germination of seeds and also a significant reduction in chlorophyll content. Hemolytic assay implied Reactive Orange was the most toxic with 90% of RBC lysis, where effluents DU1 and DU2 showed a total RBC lysis of around 87%. Artemia salina was used to determine LC50 values of reactive dyes and textile effluents. The LC50 values of the reactive dyes signified Reactive Orange as the most toxic dye with 1.7 μg/mL of dye and among effluents DU1 exhibited higher toxicity with LC50 of 15%. The study concludes that reactive dyes and textile effluents have intolerable traces of harmful heavy metals, where seed germination and hemolytic assay signified toxic effect dyes and textile effluents. Artemia salina served as an excellent model for assessment aquatic toxicity of textile dyes and dye-containing effluents.

Heavy metal determination and aquatic toxicity evaluation of textile dyes and effluents using Artemia salina

Industrial Effluents entering the water bodies is one of major sources of environmental toxicity. It not only affects the quality of drinking water but also has deleterious impact on the soil microflora and aquatic ecosystems. Soil is the most favourable habitat for a wide range of microorganisms that includes bacteria, fungi, algae, viruses and protozoa. Industries keep on releasing effluents, which is quite toxic whether its sugar mill or fertilizer industries, or chemical treatment given to the fields also cause problems for the survival of the soil micro flora. In the present study we have analyzed the effluents of sugar and textile industry and their deleterious effects on the soil microflora. Analysis of the textile effluents shows that the ph (8.1 – 9.1); TSS (190 – 163); TDS (4354 – 5768), BOD (181 - 306) and COD is (3853 – 4691) whereas in the sugar effluents ph (7.1 – 9.1); TSS (301 - 494); TDS (2560 - 3978), BOD (2225 - 4526) and COD is (10896 - 16843). The values exceed the NEQS and FMENV values. The microbial flora too is affected by it as compared to the control water sample due to the high BOD and COD values.

Siddharth Vats

Papers

Physico-chemical analysis of the industrial effluents and their impact on the soil microflora