Volume 19 - 2017

Increasing demand for water from agriculture, industrial and domestic sectors, resulted in stress on the water resources both from quantity and quality perspectives. Due to urbanization many of the dyeing units have shifted from urban to nearby rural areas. Here safe disposal of untreated effluent from the dyeing units is a challenge and is often let into nearby water bodies. Pandravedu Lake, located in Thiruvallur district of Tamil Nadu, India is one such case were the present study is carried out. Water samples were collected from twelve locations during pre-monsoon, monsoon and post-monsoon seasons, in pre-cleaned polyethylene cans and analyzed for physico-chemical parameters like pH, total dissolved solids, electrical conductivity, total alkalinity, total hardness, calcium, magnesium, sodium, potassium, iron, nitrate, chloride, fluoride and sulphate following the standard analytical procedures recommended by American Public Health Association (2005).The analytical results indicated that 40% to 70% of samples exceeded the drinking water quality standards prescribed by Bureau of Indian standards (BIS, 2012). Water quality index computed indicate that both the bore wells that supply drinking water to the village falls in very poor category (101 – 150) across three seasons. Correlation analysis indicated that seasonal changes in correlation among the parameters are linked to the fluctuations of wastewater discharge and its characteristics.

Hexavalent chromium Cr(VI) is one of the most toxic heavy metals in aqueous solutions, hence it is highly imperative to treat the wastewater containing Cr(VI) before its discharge. At present work, the rate of biosorption was studied under a variety of conditions, including initial Cr(VI) concentration (5-50 mg/L), amount of biosorbent (0.5-3 g/100 mL), pH (1-8), temperature (298-318 K) and contact time (30-120 min). Biosorption of Cr(VI) is in all cases pH-dependent showing a maximum at equilibrium pH values between 2 and 3. The biosorption data fitted well with Langmuir and Freundlich isotherms. The biosorption capacity calculated from the Langmuir isotherm was q = 33.58 mg Cr(VI)/g of dry seeds (at 303 K). Biosorption kinetics data well fitted using pseudo-second-order. Thermodynamic studies confirmed that biosorption of Cr(VI) ions by mucilaginous seeds of Cydonia oblonga was spontaneous and endothermic nature.

Solid-state fermentation (SSF) process appears to be an efficient way to recover and valorise organic residues from industries and to generate other products of industrial significance, such as enzymes. As the reproducibility of SSF is one of the main drawbacks in the development of this process, a complete study on this point was carried out. Materials with high nitrogen content, soy waste (SW) and hair waste (HW), were treated by SSF to obtain both proteases for different uses and a stabilized material for soil amendment. The bench scale reactors used in the experiments had a 4.5 l volume. Eight and five experiments were performed with the SW and HW, respectively, over a period of 2.5 years with different batches of each material. The highest production of proteases was observed after 3 days and after 14 days of fermentation, for soy and hair wastes, respectively. In the case of hair waste (HW), the overall CV was close to 4.0% for both the maximum protease activity (PA) and the maximum specific protease activity (sPA). In the case of SW, the overall CVs recorded were 43% and 18.6% for the maximum PA and the maximum sPA, respectively. This demonstrates that SSF can be a reproducible process in bench scale reactors. This is the first study and a help to researchers to develop SSF experiments in a consistent and conclusive way.Solid-state fermentation (SSF) process appears to be an efficient way to recover and valorise organic residues from industries and to generate other products of industrial significance, such as enzymes. As the reproducibility of SSF is one of the main drawbacks in the development of this process, a complete study on this point was carried out. Materials with high nitrogen content, soy waste (SW) and hair waste (HW), were treated by SSF to obtain both proteases for different uses and a stabilized material for soil amendment. The bench scale reactors used in the experiments had a 4.5 l volume. Eight and five experiments were performed with the SW and HW, respectively, over a period of 2.5 years with different batches of each material. The highest production of proteases was observed after 3 days and after 14 days of fermentation, for soy and hair wastes, respectively. In the case of hair waste (HW), the overall CV was close to 4.0% for both the maximum protease activity (PA) and the maximum specific protease activity (sPA). In the case of SW, the overall CVs recorded were 43% and 18.6% for the maximum PA and the maximum sPA, respectively. This demonstrates that SSF can be a reproducible process in bench scale reactors. This is the first study and a help to researchers to develop SSF experiments in a consistent and conclusive way.

The present study was conducted to compare the performance of different solar photocatalytic processes (TiO2 photocatalysis, photo-Fenton, photo-Fenton coupled with TiO2 photocatalysis, and photo-Fenton coupled with TiO2/ZnO photocatalysis) for the treatment of petroleum wastewater. The removal efficiency of chemical oxygen demand (COD) is evaluated. TiO2 dosage and pH are the main factors that improve the COD removal in the TiO2 photocatalysis process while Fe+2 and H2O2 concentration are the main factors in photo-Fenton process. The photo-Fenton coupled with TiO2/ZnO photocatalysis is the most efficient process for treatment of petroleum wastewater at the neutral conditions (pH 7). Therefore, no need to adjust pH during this treatment. In acidic conditions (pH<7), the photo-Fenton process is more efficient than the TiO2 photocatalysis process while it is less efficient than the TiO2 photocatalysis process in alkaline conditions (pH>7).