Evaluation of the biosolids compost maturity in south Isfahan wastewater treatment plant

The composting process is a useful method of producing a stabilized material that can be used as a source of nutrients and soil conditioner. Maturity of compost is essential for its optimal use as a soil amendment and a source of plant nutrients as well. Immature composts pose problems of malodors and flies and phytotoxicity and pollution during use. Stability and maturity both are required for compost quality control. Compost maturity tests can be classified into physical, chemical, plant, and microbial activity assays. In this study, several methods of evaluating the stability and maturity of composted biosolids were compared based on chemical and biological properties. The sludge used of windrow composting was obtained from the drying beds of South Isfahan wastewater treatment plant. The results showed that, C/N ratio after 100 days of composting reached to 15/1; NH[4]/NO[3] ratio decreased with increase of the time dewatered sludge compost, which this loss is 57.3%. The content of volatile solids, 28.8% decreased with composting time. The number of fecal coliforms in the initial sewage sludge compost was 17.9 x 10[6] and at the end of composting was 898MPN/g of total solids and the compost process provided class A pathogen criteria. Use of chemical and biological parameters exhibited three phases: rapid decomposition [day 40], stabilization [day 80] and maturation [day 100] in biosolids compost. Thus, the biosolid compost was mature and ready for use as an agricultural substrate after about 100 days of composting

Heavy metals Bioaccumulation by Iranian and Australian earthworms [Eisenia fetida] in the sewage sludge Vermicomposting

Vermicomposting of organic waste has an important part to play in an integrated waste management strategy. In this study, the possibility of heavy metals accumulation with two groups of Iranian and Australian earthworms in sewage sludge vermicompost was investigated. Eisenia fetida was the species of earthworms used in the vermicomposting process. The bioaccumulation of Cr, Cd, Pb, Cu, and Zn as heavy metals by Iranian and Australian earthworms was studied. The results indicated that heavy metals concentration decreased with increasing vermicomposting time. Comparison of the two groups of earthworms showed that the Iranian earthworms consumed higher quantities of micronutrients such as Cu and Zn comparing with the Australian earthworms, while the bioaccumulation of non-essential elements such as Cr, Cd, and Pb by the Australian group was higher. The significant decrease in heavy metal concentrations in the final vermicompost indicated the capability of both Iranian and Australian E.fetida species in accumulating heavy metals in their body tissues

Study of the effect of residual chlorine on serum iron and related parameters

The major purpose of the present investigation was to study the effects of different concentrations of residual chlorine on serum iron related parameters in rats. Feeding male rats with water containing 80 ppm of residual chlorine daily for 5 days reduced serum levels of ceruloplasmin, copper, iron and hemoglobin by approximately 27%, 23%, 6% and 4%, respectively. Higher reductions in serum ceruloplasmin [35%], copper [50%], Fe [17%] and hemoglobin [14%] were observed when rats were given water containing 160 ppm of residual chlorine daily for 5 days. The total iron binding capacity [TIBC] level was elevated by 9 and/or 13% respectively. Daily feeding of rats for 10 days with water containing 160 ppm residual chlorine caused significant reductions in serum levels of ceruloplas min [50%], copper [54%] iron [17%] and hemoglobin [17%]. Serum TIBC was elevated by 25%. Long term effects of residual chlorine on the above parameters were also investigated. It can therefore be concluded that residual chlorine in drinking water may interfere with iron metabolism. The relationship between the occurrence of anemia and residual chlorine toxicity has been discussed