IRANIAN JOURNAL OF HEALTH AND ENVIRONMENT
Year:2011 | Volume:4 | Issue:3 (13)|Papers Count:12

Background and Objectives: One of the complete treatment processes for industrial and municipal wastewater treatment is membrane bioreactor process which has dominant potential in process and operation sections. This study was conducted to compare the performance of extended aeration activated sludge (EAAS) with submerged membrane bioreactor (SMBR) systems in the treatment of strength wastewater, in the same condition. Materials and Methods: The initial activated sludge was brought from the Plascokar Saipa wastewater plant. The Plexiglas reactor with effective volume of 758 L was separated by a baffle into the aeration and secondary sedimentation parts with effective volumes of 433 L and 325 L, respectively. The chemical oxygen demand (COD) concentration of the influent wastewater of the EAAS and SMBR systems were between 500-2700 and 500-5000 mg/L, respectively. Results: Results showed that the SMBR system produced a much better quality effluent than EAAS system in terms of COD, biochemical oxygen demand (BOD5), total suspended solids (TSS) and ammonium. By increasing the COD concentration, the concentration of mixed liquor suspended solids (MLSS) and the removal efficiency of organic matter in the SMBR system, were increased regularly, however the removal efficiency of COD in the EAAS system was irregular. Conclusion: The average BOD5/COD ratio of effluent in the EAAS and SMBR systems were 0.708±0.18 and 0.537±0.106, respectively. These show that the organic matters in the effluent of the SMBR system was less degradable and thereupon more biological treatment was achieved. Nitrification process was completely done in the SMBR system while the EAAS system could not achieve to complete nitrification.

Backgrounds and Objectives: Selection of proper coagulants for turbidity removal and determination of effective methods to reduce coagulants dose and related costs in water treatment plants is of critical importance. The present study investigates the effect of returned sludge on improving the performance of poly-aluminum chloride (PAC) in turbidity, coliform bacteria, and heterotrophic bacteria removal from drinking water during rapid mixing phase. Materials and Methods: In order to determine the optimal returned sludge volume injected during rapid mixing with PAC for turbidity, total coliform and hetrophic bacteria, experiments were conducted based on variables such as injected silt volume (from 0 - 125 ml), and varying turbidities from 58 - 112 NTU. At the end of each JAR experiments, remaining turbidity, microbial parameters of samples were measured. Coagulant efficiency in turbidity removal and microbial parameters were determined by Covariance, Duncan analyses and graphs were drawn by MS Excel. The results statistically showed significant among variables (P<0.05). Results: The results showed that the maximum turbidity removal efficiency of 98.92 at 30 ppm was 10 ml while the maximum turbidity removal efficiency of 98.31 at 10 ppm was 4 ml. The maximum total coliform removal efficiency of 95.68 obtained for 10 ppm in 10 cc injected sludge volume.Conclusion: This study shows that addition of returned sludge to flash mixing can reduce the turbidity of samples.

Background and Objectives: Water pollution by pesticides has adverse effects on the environment and human health, as well. In recent years, advanced oxidation processes, have been gone through to a very high degree for pesticides removal. Poly- Aluminum chloride (PAC) used for water treatment, can be effective on pesticides removal. The aim of this research was to study the use of UV/O3 and PAC in the removal of pesticides from drinking water.Materials and Methods: In this descriptive- analytical survey, specific concentrations of pesticides (1, 5, 10, 15, 20 ppm); namely Diazinon, Chlorpyrifos, Carbaril were prepared through addition to deionized water. Dichloromethane was used for samples’ extraction, samples extracted with Liquid- Liquid & Solid- phase extraction, finally entered bath reactor at pH (6, 7, and 9). The samples then exposed to UV/O3at contact time of (0.5, 1, 1.5 and 2 hours). In the PAC pilot, the effects of various concentrations of pesticides, and PAC - ranging (12/24 and 36 ppm) were investigated for the efficacy of pesticides removal. All samples analyzed by GC/MS/MS and HPLC. Results: It was found that in UV/O3 reactor, with the rise of pH, decrease in pesticides concentration, and rise of contact time, the efficiency of removal increased too. In the PAC pilot, increase in PAC concentration and decrease in pesticides concentration, both increased the efficiency. Besides, both of the methods showed high efficiencies in the removal of both pesticides, i-e. Halogenated Organophosphorus (Chlorpyrifos), non- halogenated Organophosphorus (Diazinon) at the degree of over (%80); In case of carbamate pesticides (e.g. Carbaril) efficiency was over (>%90). One-Way Anova & Two -Way Anova were used to analyze the obtained data.Conclusion: According these results these two methods are suggested for the removal of pesticides from aqueous solutions.

Background and Objectives: Industrial wastewater included the cyanide is one of the important sources of environmental pollution which founded in Industrial wastewater which are harmful for human health and environment. Therefore, the purpose of this research that was fundamental designed is investigation of Removal of cyanide from aquatic solution by using of iron and copper powder in experimental scale.Material and Methods: At first, pilot was designed. Then, acquired pH optimum equal to 2, 7 for copper and iron by variation pH= (2, 4, 6, 8, 12) and constant other parameters. The effect of initial cyanide concentration (40, 60, 80 mg/l), initial iron and copper dosage (0.08-1 g/100CC) and contact time (15-12 min) studied at the constant of optimum pH.  Results: The result showed removal efficiency Increased from 46.6% to 90.56% and 31% to 93.78% for copper and iron by increasing of contact time from 15to 120 minute in constant conditions, respectively. Also result showed Removal efficiency decreased and increased by increasing initial cyanide concentration and initial iron and copper dosage. The results showed equilibrium data were explained acceptably by Langmuir isotherms and kinetic parameters were obtained by application of Langmuir & Hinshelwood equation.Conclusion: The results showed that removal of cyanide can be quick and effective done by iron and copper in experimental scale.

Backgrounds and Objectives: Improvement of water quality standards and inability of mono layer filters in producing such quality caused researchers attended to multi-layer filters.Due to specific characteristics of anthracite and leca can improve removal of organic materials and Surface over flow rate.The aim of this research was evaluation performance of dual media filters (anthracite/leca) in removing of organic materials and turbidity from Ahvaz Water treatment plantMaterials and Methods: In this study two pilots built for investigation of mono layer filter and dual media filter performance. The researcher used sand in structure’s media of mono layer filter and composition of anthracite, sand and leca in structure’s media of dual media filter, respectively. In this study single and dual layer filter pilot examined in term of organic matter and turbidity removal efficiency.  Results: Results indicated that removal of organic matter by single layer filter (sand), dual media filter (anthracite, and sand), dual media filter (leca and sand) was 7%, 12%, 4/2% respectively. And also Turbidity removal by single layer filter (sand), dual media filter (anthracite and sand), dual media filter (leca and sand) was also 69%, 80%, 74% respectively.Conclusion: Results of this study showed that upgrading of Single layer to dual layer with anthracite and leca media can‘t show a significant affect in TOC removal.

Background and Objectives: New studies indicate that nitrate concentration in groundwater is increasing in most cities. High concentrations of nitrate in water increase the potential health risk in the community and the environment. In infants, No3- is reduced to No2-, which combines with hemoglobin in the blood to form met hemoglobin leading to blue-tinged blood for babies under six months old in particular ,Namely, so-called ‘‘blue baby syndrome’’ and it also produce carcinogenic compounds. Therefore high nitrate concentration is important.The aim of the present study is removing nitrate from water using zero_valent iron.Materials and Methods: Analyses were conducted on synthetic samples. These samples were analyzed considering reaction times, pH, initial nitrate and sulfate concentration.Results: Results showed that at Nitrate with an initial concentration of 200mg L1- after 60 min of reaction at pH (s) 7, 6 and 5 about 67.8%, 72.5 % and 88% was reduced, respectively in concentration of 100 and 300 mgL- (pH=6) the removal efficiency is 60 and 83 percent, respectively. In sodium sulfate and nitrate with concentration of 300, the removal efficiency reached from 72 to 70 percent. Conclusion: Results show that the initial pH is important to achieve maximum efficiency of nitrate removal. So the lower pH levels increases removal efficiency of nitrate. All of the experiments indicated that removal is the highest in the first 5 min. Generally with an increasing initial nitrate concentration the removal efficiency of nitrate increases.