Feasibility of utilizing moving bed biofilm reactor to upgrade and retrofit municipal wastewater treatment plants

In this study, feasibility of upgrading and retrofitting municipal wastewater treatment plants was investigated at laboratory scale using Moving Bed Biofilm Reactor [MBBR] process. For this purpose, an aerobic pilot was operated for nearly one year in different conditions, in which a moving bed carrier with a specific biofilm surface area of 500 m[2]/m[3] and a filling rate of 60% was utilized. System efficiency in removal of BOD[5] and COD was examined at different hydraulic retention times [HRTs] of 1, 1.5, 2, 2.5, 3 and 4 h. The obtained results indicated high ability of the system to tolerate organic loading and to remain stable at a high food to microorganism [F/M] ratio. The system produced effluents with good quality at low HRTs and led to an average BOD[5] removal efficiency of nearly 88% during the operational period. The Organic Loading Rate [OLR] applied to the system had a range of 0.73-3.48 kgBOD[5]/m[3].day and 2.43-11.6 gBOD[5]/m[2].day, at which the reactor showed a good performance and stability. In general, it was concluded that [MBBR] can be an excellent alternative for upgrading and optimizing municipal wastewater treatment plants

Level changes of traffic noise in Kerman city, southeast Iran

The purpose of this research was to determine the traffic noise level and changes in the Kerman City, southeast Iran in recent years. This cross-sectional study was carried out in 2008 to investigate the existing noise situation in Kerman. Sound levels [L[max], L[min], L[eq], L[99], L[90], L[50] and L[10] were determined throughout 13 stations using sound level measurement system [model, CEL-440]. Number of passing vehicles was also assessed at the sampled stations. Sound level in all sampled stations was higher than Iran and World Health Organization guidelines. Comparison of L[eq] in different hours using statistical tests showed significant difference between different hours with 95% confidence coefficient [P=0.01]. Comparison of L[eq] throughout the week also showed that there was a significant difference [P=0.001] between Friday and workday. The comparison of L[eq] with the number of passing vehicles using Pearson correlation statistical test showed significant difference between the number of heavy vehicles passed and the level of L[eq] [P=0.001]. It also showed that number of heavy vehicles caused the most noise levels. The results of this study compared to a similar study conducted in 1999 showed an increasingly high noise level. Noise level increased from 1999 to 2008 by 3.89% which is indicative of an increase in noise emission sources

Determination of Pb,Cd,Cr and Ni concentration in Imported Indian Rice to Iran

Heavy metal pollution has always been a major cause contamination of environment and considered as a major concern for food health. Rice is the most popular food among Iranians and presence of heavy metals in trace level in rice has received special attention because they are directly related to health. The aim of this research was to investigate the concentration of Pb, Cd, Cr, Ni in rice prevalent in the market of Iran. 20 of the most widely consumed brands of Iranian rice were purchased from local market in Iran. 3 samples of each brand were collected and certain volumes of each sample were digested with acid. Heavy metal contents in the digested samples were determined by atomic absorption spectrometry. The results showed that mean concentration Pb, Cr, Ni in rice samples respectively was 0.387, 0.683, 0.019 [mg/kg]. Notably the Ni and Cr content in the rice samples was found to be below the food sanitary standards in India rice. In the other hand 50% samples content Pb was found to be upper the food sanitary [Pb: 0.3 mg/kg]. The result indicated that weekly intake of heavy metal by rice was below the provisional tolerable weekly intake recommended by WHO/FAO. However, risk assessments needs considerable attention and better prevention this low pollution

[Investigation of existing status of hazardous wastes management in central campus of Tehran university medical sciences, Iran]

Due to having features such as toxicity, corrosiveness, ignitability, reactivity or other similar characteristics, hazardous wastes refer to the wastes that jeopardize man's health and environment. A study was required to identify the hazardous wastes in Tehran University of Medical Sciences [TUMS], since it plays an important role in the development of the country's education. The objective of this research was to provide a review of hazardous wastes production and its management at Tehran University of Medical Sciences. In this study, four schools that were in the central campus of Tehran University of Medical Sciences, Iran, were selected and the necessary data were gathered using a sampling, questionnaire, interviewing those in charge of the units, and referring to the available documents. The information includes the type and amount of waste, method of temporary storage, frequency of waste discharge, and method of final disposal of wastes. The obtained results indicate that approximately 2072 Kg of hazardous wastes are produced each year, excluding the uncontrolled waste water. Moreover, schools of dental, pharmacy, medicine, and public health produced approximately 993, 606, 256, 217 Kg/year, respectively, of hazardous wastes in the central campus. Also, the results show that, of total amount of annual hazardous waste that was 2.72 tons, 954, 848, 475, 427, 245, 49 Kg were wastes that the features infectious, toxicity, ignitability, carcinogenesis, corrosiveness, and reactivity, respectively. It is to be mentioned that hazardous solid wastes were manage with household solid waste and hazardous liquid waste were discharged into sink without any kind of control. Improper practice is evident from the point of waste production to final disposal

Quality and quantity survey of hospital wastewaters in hormozgan province

Hospital wastewaters are one of the most contaminating wastewaters and need to be paid more attention due to containing infectious agents. In this study, which had been conducted in a period of one year, 7 public hospitals were selected out of 12 public hospitals in Hormozgan Province of Iran. For studying quality of wastewater in hospitals, both influent and effluent wastewaters of treatment plant, if any, were sampled once in each season and totally 30 mixed samples were obtained. In order to determine the quality of hospital wastewaters in all samples, parameters such as pH, BOD[5], COD, TSS and temperature were measured. Results of investigation on annual water consumption indicated that average water consumption in hospitals of the province was 194m[3]/d., considering water-to-wastewater conversion ratio of 0.8 and green yard ratio of 0.3. Wastewater production rate had been estimated to be 47m[3]/d and 0.362 m[3]/d.bed. Results indicated that in 7 hospitals of Hormozgan province, mean values of BOD[5], COD, TSS in raw wastewater were 242.25 mg/L, 628.1 mg/L and 231.25 mg/L, respectively, pH=7.42 and temperature=30.17 °C. In Khalij-e-Fars hospital which had wastewater treatment plant, values of these parameters in effluent were 12.53 mg/L and 51.7 mg/L, 19.68 mg/L, respectively, with pH=7.39 and temperature=26.1 °C. Comparison between values of influent and effluent wastewaters indicated that in understudy cases, contamination rate was higher than determined limits, as compared to environmental standards of the country and it was necessary to establish appropriate treatment plants in these units

Comparison between windrow and pit composting of poultry wastes, leaves and garbage of municipal solid waste in Damghan, Iran

Basic principles of Integrated Solid Waste Management [ISWM] are: Reduction, Reuse, Recycling and Recovery [411s]. Composting as an element of ISWM strategy that can be applied to separately collected or mixed wastes, is a controlled aerobic process carried out by successive microbial populations com-bining both mesophilic and thermophilic activities and leading to the production of carbon dioxide, water, minerals and stabilized organic matter. In this research, comparing between windrow and pit co-composting methods was studied in the city of Damghan, Iran. Waste proportioning was done based on C/N ratio [about 25:1] and moisture content [about 55%]. Mixed wastes were located in windrow and pit with natural aeration tunnel. Sufficient oxygen supply was provided in the piles of compostable materials in two systems through frequent turning of the piles in 7 d intervals during the first month. Temperature reached to maximum level in 10-15 d and then depleted [days: 20-25]. It reached to the safety level [about 60°C] based on U.S.EPA and WHO recommendations. Finally, compost was produced with pll=7.7, dark brown color and 30- 35% moisture content. N, P, K, organic matter and organic carbon were measured by standard methods. Results were compared with WHO and U.S.EPA recommendations showing suitable conditions Also it was indicated that pit method was better for maintaining temperature, nitrogen, organic C and organic matter

Kinetic and equilibrium studies of lead and cadmium biosorption from aqueous solutions by Sargassum SPP. Biomass

Contamination of the aqueous environment by heavy metals is a worldwide environmental problem. Biosorption of lead [11] and cadmium [II] from aqueous solutions by brown algae Sargassum spp. biomass was studied in a batch system. The heavy metals uptake was found to be rapid and reached to 88-96% of equilibrium capacity of biosorption in 15min. The pseudo second-order and saturation rate equations were found in the best fitness with the kinetic data [R2 > 0.99]. The data obtained from experiments of single-component biosorption isotherm were analyzed using the Freundlich, Langmuir, Freundlich-Langmuir and Redlich-Peterson isotherm models. The Redlich-Peterson equation described the biosorption isotherm of Pb2+ and Cd2+ with high correlation coefficient [R2 > 0.99] and better than the other equations. The effect of Na+, K+, Mg2+ and Ca2+ on the biosorption of Pb2+ was not significant, but the metal ions affected the biosorption of Cd2+ considerably. According to the Langmuir model, the maximum uptake capacities [q m] of Sargassum spp. for Pb2+ and Cd2+ were obtained as 1.70 and 1.02mmol/g, respectively. Although the Sargassum spp. used in this study can be classified as an efficient biosorbent

Investigation of carbon monoxide in heavy traffic intersections of municipal districts

In this research, an investigation of carbon monoxide in heavy traffic intersections of Kerman municipal districts in 2003-2004 has been performed. Kerman City is located at the south-eastern part of Iran. Carbon monoxide in highly toxic for human health and natural ecosystems in metropolition districts especially due to high traffic and industrial activities. For this reason, it was decided to investigate and find out the high concentration of CO pollutants in heavy traffic intersections of Kerman City. In this regards 21 heavy traffic squares and intersections were selected and the concentration of CO were measured. In the middle of each month during the year, sampling and measurement were scheduled three times at daily times according 7-12 a.m.; 12-16 and 16-20 p.m. In each period, 12 samples of 5 minutes were collected and CO concentration for 1-hr was calculated. The results obtained indicate that the hourly mean concentrations were lower than WHO guidelines and also lower than measurements of 1989, which has already done. In spite of more cases and higher populations, natural gas distribution was the cause of decline in CO concentrations