Enhancement of organic removals in high strength herbal pharmaceutical wastewater.

Herbal Pharmaceutical wastewater was subjected to physico-chemical treatment using conventional coagulants individually and in combination with different anionic, cationic and nonionic polyelectrolytes. Results indicate cationic polyelectrolyte to be the best polymer. Individually Alum did not give good results but Alum with cationic polymer in the ratio of 300:0.25 mg l(-1) resulted in the best removals of Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Suspended Solids (SS) of 64.0%, 69.4% and 80.82% respectively. The next combination which resulted in good removals was Lime: cationic polymer in the ratio of 300:0.20 mg l(-1) with COD, BOD, and SS removals of 57.6%, 65.1% and 74.0%, respectively. Overall the studies indicated that the herbal pharmaceutical wastewater needs to be treated by physico-chemical treatment as a primary process to reduce the organic load and increase the performance efficiency of the secondary biological treatment process. This paper discusses in detail the studies carried out using conventional coagulants along with synthetic polyelectrolyte.

Toxicity of herbal pharmaceutical wastewater on fish--Lebistes reticulatus (Peter).

Toxic effects of herbal pharmaceutical wastewater on common fish (Lebistes reticulatus) under laboratory conditions were studied. LC50 values for raw, neutralized, and physico-chemically treated effluent for 24, 48, 72, and 96 h ranged between 3.0-9.5%, 5.0-10.5%, and 35-41%, respectively. It was evident from the studies that physico-chemical treatment reduces the toxicity by more than 30%. This article discusses in detail the bioassay evaluation of raw, neutralized, and primary treated effluent. Physico-chemically treated effluent was further subjected to biological treatment by activated sludge system. Effluent from biological treatment revealed no toxic effect even after one month of exposure.

A comprehensive investigation of noise exposure in and around an integrated iron and steel works.

A comprehensive environmental noise exposure study was carried out in and around a major iron and steel works. The works was located in the central part of the city and was surrounded by residential, commercial, and sensitive receptors. Traffic activity near the plant was significant and added to the background noise level. Considering the variety of noise sources in the plant area and in the neighborhood, a practical approach to measure noise equivalent level in the plant and in the residential, commercial, industrial, and silence zone was adopted. A modular precision integrating sound level meter with statistical analyzer module, octave filter set, and calibrator were used during the measurements. The day and night level, Ldn, was determined. Worker exposure was assessed by determining the speech interference level (SIL), loudness level, and noise rating level at one of the major sources located in the power plant of the steel works. The results indicate that SIL was 94 dBA, loudness level was 112 phons, and the noise rating was in the range of 85-95. A traffic noise index also was determined near the works gates and was in the range of 68-96. The impact on the community is significant as observed from Ldn levels. Some mitigation measures for noise control are also discussed.

Retrieval of heavy metal ions from solution via ferritisation.

The paper summarises the results of the studies on retrieval of heavy metal ions in solution by ferritisation and its potential application in waste-water treatment. The optimum procedure for ferritisation of heavy metal ions in solution has been evolved with respect to pH, concentration of Fe2+, rate and time of aeration and temperature. The recommended procedure consists of controlled aeration of the solution containing heavy metal ions and ferrous ions at pH 9.5-10.5 at about 50 degrees C, until the black, granular, magnetic ferrite separates out. The metal ferrites can also be formed, even without heating or forced aeration, by ageing the mixed metal hydroxide precipitate at pH 10 to 11. The metal ferrites formed have been characterised by X-ray diffractometry. The laboratory-scope experiments conducted with synthetic heavy metal solutions as well as actual wastewater from a tanning industry showed that heavy metal ions can be effectively removed from solution to sub-ppm levels. The metal ferrites thus recovered may find commercial application as microwave absorbers, catalysts, metal scavengers, etc. This technique seems to have potential application in simultaneous, one step removal of different heavy metal ions from industrial wastewaters.