ABSTRACT
In most societies nowadays, accidents are considered as the second most probable cause of death. A big ratio of this is related to the traffic accidents. This report aims at recognizing the accidents which cause casualties around Mashhad's roads. In a case-control study, the cases were drivers who had accidents in these roads with casualties and the controls were the drivers having accidents in same locations but with no casualties. Variables were age, sex, seat belt, spontaneous combustion at the accident, trapping at the accident, falling out of the vehicle at the accident, music playing in the vehicle at the time of the accident, using cell phone, the direction of the accident, the time, smoking at the time of the accident, and the model of the vehicle in both groups. Ninety percent of the cases and 93% of the controls were able or willing to be interviewed while 16.2% and 23.4% of the cases and controls were female. The distribution of males in the case and control group was 83.8% and 76.6% respectively. The age of the case and control groups was 35.5 +/- 10.5 and 39.4 +/- 9.8 years. The use of seat belt as a safety factor was significantly more in the control group [OR=0.44]. Combustion was 21% seen in the case group at the time of the accident, but the same occurred in the control group only in 1.3% of the accidents. The trapping and falling out of the vehicle were significantly more in the case group. Fastening seat belt had a significant positive effect on reducing the injuries caused by the accidents. Age as another significant indicator showed a great influence in the danger factor caused by the road accidents which can be reduced by means of media information
ABSTRACT
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
Subject(s)
Waste Disposal, Fluid , Soil , Sewage , Waste ManagementABSTRACT
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
ABSTRACT
Traditional thermophillic composting is commonly for treatment of sludge. A related technique as vermicomposting process, using earthworms to breakdown sludge, is also becoming popular. These two techniques have their inherent advantages and disadvantages. The combined approach suggested in this study to enhance the overall process and improve the products qualities. Two systems,vermicomposting and combined compost vermicomposting processes, have been investigated in this study. The sludge used in this study was obtained from the drying beds of South Isfahan wastewater treatment plant.The sludge mixed with sawdust to provide C/N ratio of 25/1.Eisenia fetida was the species of earthworms used in the vermicomposting processes.The results obtained indicates reduction in the amount of volatile solids,total carbon and C/N ratio with the vermicompost age,which indicates the reduction in the biodegradable organic content and mineralization of sludge. Also increase in phosphorus concentration by the end process because of mineralization of organic matter. The results indicate that, a system that combines the two mentioned processes not only shortens stabilization time, but also improves the products quality. Combining the two systems resulted in a product that was more stable and homogenous; the product could meet the pathogen reduction requirements
Subject(s)
Soil , Oligochaeta , Phosphorous AcidsABSTRACT
Improving the soil quality with organic matter content and presence of elements such as N, P and K are some of sewage sludge benefits. Adjusting carbonaceous materials such as plant wastes to dewatered sludge compost increases its moisture and improves C/N ratio. So dewatered sludge has low C/N ratio and should be mixed with bulking agents. This study was performed in a three months period of the year 2002, in laboratory of Chemistry of Water and Wastewater in the School of Public Health of Isfahan University of Medical Science, to determine the C/N ratio and heavy metals concentration of bulking agents in sawdust, leaves, rice hulls and dewatered sewage sludge. The results showed that concentration of chromium and cadmium in the mixture of dewatered sewage sludge and bulking agents was lower than the standard level. Means of cobalt [115.44 mg/kg], nickel [57.44 mg/kg] and zinc [273.48 mg/kg] concentrations were maximum in dewatered sludge but mean concentration of cobalt [25.66 mg/kg] in rice hull samples and mean zinc [8.99 mg/kg] and nickel [5.106 mg/kg] concentrations in sawdust samples were minimum. The optimal conditions sewage sludge composting, each kilogram of sludge needs 350 grams of saw dust, 470 grams of leaves and 388 grams of rice hull. Amount of heavy metals present in the bulking agents is lower than the amount mentioned for the compost