Eco-friendly approach for leaching out heavy metals from sewage sludge

Sewage sludge contains rich organic matter and nutrients essential for the growth of plants but the presence of toxic heavy metals restricts its land application. To overcome this, the study aims an eco-friendly approach for leaching out heavy metals. Sewage sludge from sewage treatment plant, Chennai, India was characterised. The analysis of total heavy metal concentration was done by digesting in nitric acid and different forms were extracted by community bureau of reference sequential method. Heavy metals: As, Cd, Cr, Cr, Ni, Pb and Zn were determined using inductively coupled plasma optical emission spectrometry Perkin Elmer Optima 5300 DV. The experimental set-up for heavy metal leaching was held for five consecutive days at different concentrations of humic acid (0.1%, 0.5% and 1%) at varied pH (5–9). Results revealed that at the end of fifth day at pH 8, 1% humic acid is capable of leaching out 75.5% cadmium, 66.0% nickel, 52.0% lead, 51.2% zinc, 31.2% copper and 8.5% cadmium from sewage sludge. Statistically positive correlation (0.7088) existed between the percentage of heavy metals leached out and the sum of soluble and reducible fractions. Thus, from ecological point of view, humic acid can be used to leach out heavy metals from sewage sludge serving the need in restoration of soil fertility upon land application.     

The validity of situational interviews for administrative jobs

This study was conducted to determine the validity of situational interviews for making predictions of ratings of job performance and potential. The validation sample consisted of 63 candidates. The correlations of potential and performance with situational interview scores were statistically significant and both predictor and criterion measures showed acceptable levels of reliability. The study provides additional evidence on the validity of situational interviews in a new job family, i.e. administrative jobs in a large U.K. financial services organization. The discussion questions the extent to which situational interviews provide unique or overlapping predictive validity when compared with mental ability tests.     

Monitoring of cellular enzymes in the serum of electroplating workers at Coimbatore

Chromium compounds are potent toxic and carcinogenic substances. With respect to toxicity, hepatic and renal toxicity have been reported both in workers and in animals exposed to chromium (VI). Chromium (VI) compounds induces DNA damage in vivo and in cultured cells as well as the cytotoxicity evaluated by the leakage of lactate dehydrogenase. The present study reports the cytotoxicity of chrome platers who are employed from 8 to 25 years in electroplating industries at Coimbatore, Tamilnadu. Blood samples were collected and estimated for glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and total protein in the serum. The study revealed that there is a significant elevation in the level of LDH, ALP, CPK and transaminases and a decrease in total protein in serum. The results of the study suggests that chromium (VI), a hepatotoxic chemical may perhaps damage the plasma membrane resulting in leakage of enzymes in to the serum of chromeplaters.