Performance evaluation of an anaerobic baffled reactor treating wheat flour starch industry wastewater

Feasibility of the anaerobic baffled reactor process was investigated for the treatment of wheat flour starch wastewater. After removal of suspended solids by simple gravity settling, starch wastewater was used as a feed. Start-up of a reactor [with a volume of 13.5 L and five compartments] with diluted feed of approximately 4500 mg/L chemical oxygen demand was accomplished in about 9 weeks using seed sludge from anaerobic digester of municipal wastewater treatment plant. The reactor with hydraulic retention time of 72h at 35°C and initial organic loading rate of 1.2 kgCOD/m3.d showed 61% COD removal efficiency. The best performance of reactor was observed with an organic loading rate of 2.5 kgCOD/m3.d or hydraulic retention time of 2.45 d and the COD conversion of 67% was achieved. The system also showed very high solids retention with effluent suspended solids concentration of about 50 mg/L for most organic and hydraulic loadings studied. Based on these observations, the ABR process has potential to treat food industrial wastewater as a pretreatment and is applicable for extreme environmental conditions

Evaluation of chronological aspects of collection and transportation of municipal solid waste system in Urmia

Municipal solid waste [MSW] is a serious environmental hazard and social problem in Iran. Currently a high volume of solid waste is generated every day in the district towns of Iran and unfortunately solid waste management is being deteriorated due to the limited resources to handle the increasing rate of generated waste. Due to this fact that more than 60% of solid waste management cost is usually alocated for purpose collection and transportation of generated solid waste in the city. Analysis of this section and understanding of its effect on the management system could have a great role in reduction the costs and solving many of exist problems. This study illustrate the effectiveness of timing managing an MSW economy and that has been carried out as a case study in Urmia. Results of this research illustrsate that 58.3% in Neisan, 68.7% in Khavar, 61.5% in Benz, 81.3% in Compactor and 59.3% in FAUN of each cycle time is pickup time. Mean of traveling speed for Van, Mini-truck, Truck, FAUN and Compactor was 35,46,41,38 and 42 kilometer per hour respectively. Total spent time for collection and transportation of solid waste were 1:21 hour with Van, 1:23 hour with Mini-truck, 1:29 hour with Truck, 17 minutes with FAUN and 57 minutes with Compactor. Result of this study illustrated Van is the most economic vehicle for solid waste collection system in Urmia city. Generally, priority to usage of solid waste collection vehicles illustrate in below: Truck < Mini-truck < Compactor < Van < FAUN

employment situation of environmental health graduates in Iran between 1996 - 2002

Each year, the Medical Sciences Universities admit a number of young individuals for the study in the field of environmental health. This admission has been largely increased since 1996. Thus, the employment of these graduates remains as a difficulty in this field. This study was carried out to determine the occupational situation of different levels of environmental health graduates and to suggest some strategies for long term planning. In this descriptive survey, 972 graduates of environmental health with associate, BS and MS degree, throughout the country, who were selected by simple random sampling method, filled a self-administered questionnaire. The validity and reliability of the questionnaire was confirmed by content validity and test/re-test. Data analysis was done by SPSS software using frequency distribution and Chi2 test. Based on the results, 64.6% of graduates holding associate degree, and 42.7% of graduates holding BS degree were unemployed pending June 2003. The percentage of unemployment rate among MS graduates was much less than other graduates [3.7%]. Meanwhile, among associate and BS degree graduate, the highest percentage of unemployment rate was for female graduates. Due to the high percentage of unemployment in associate and BS graduates of environmental health, it is recommended to reduce the students' admission capacity. It is also suggested to enhance the academic knowledge and capabilities of graduates by making some revisions in the curriculum content, and to provide necessary background for their future employment. Since more unemployed graduates are among females, it seems that environmental health field is a kind of manly job. Therefore, more cautious is needed in admitting more female students

Vermistabilization of municipal wastewater sludge with Eisenia fetida

Sludges are stabilized to reduce pathogens, eliminate offensive odors and inhibit, reduce or eliminate the potential for putrification. In this study, stabilization of municipal wastewater sludge with and without earthworms [Eisenia fetida] was tested in a pilot study. The earthworms were fed at the optimum level of 0.75 kg-feed/kg-worm/day. Decomposition and stabilization of wastewater sludge occurred both in the presence and in the absence of earthworms during 9 weeks but the process was accelerated in their presence. Phosphorus content increased in the sludge with earthworms but decreased in it without them. Nitrogen content in the resulting vermicompost showed no difference with its quantity in the original substrate while it increased in the control treatment

Determination of carbon/nitrogen ratio and heavy metals in bulking agents used for sewage composting

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