WATER AND WASTEWATER
Year:2005 | Volume:16 | Issue:3 (55)|Papers Count:9

Considering contamination of drinking water to arsenic in some villages of Iran. In order to develop a simple method for household water treatment in rural areas, efficiency of  modified activated alumina with iron compounds- a product of Alcan Company with trade name of AAFS-50- was studied Equilibrium batch experiments were carried out using shaker incubator and arsenic was analyzed with SDDC method. Effects of initial concentration of arsenic, adsorbent dose, oxidation state of arsenic, pH and oxidation with chlorine on adsorption were studied. Correlation coefficient of Freundlich and Laungmuier isotherms for As (V) and As (III) were 0.964, 0.991 and 0.970, 0.978 respectively. These results show that adsorption of arsenic on modified activated alumina is compatible with both models specially Laungmuier models. Removal efficiency of As(V) at 0.5 ,1 and 2 hr increased with doubling the adsorbent dose from 44.8 to 72%, 69.6 to 90.8 and 92.4 to 98%; respectively. Experiments using different concentrations of arsenic showed that adsorption of arsenic on activated alumina are a first order reaction that is, rate of reaction is dependent on intial; concentration of arsenic. Removal efficiency for concentration of 0.250 mg/L of arsenic, with increasing of reaction time from 15 min to 60 min, increased 1.54 times and reached from 61% to 94%. During 2hrs, removal of As (V) and As(III) were 96% and 16% respectively. Using 1.5 mg/L Chlorine as oxidant agent, removal of As (III) was increased to 94%. In the case of pH effect, rate of adsorption increased for arsenic, with increasing of pH to 8 and decreased with more increasing, so that adsorption at pH 14 was equal to pH 2. For arsenate, the most adsorption was observed at pH between 6 to 8. These results show that by using the studied activated alumina, there will not be need for adjustment of pH and the activated alumina used in this study could have application as a safe adsorbent for removal of arsenic from drinking water in simple household treatment systems in form of adsorptive column.

Among the consequences of discharging industrial wastes to land and water bodies, is the widespread accumulation and migration of toxic chemical mixtures in soil and groundwater resources. It is believed that the accumulation of contaminants in the environment constitutes a serious threat to ecological and human health. Bioremediation is an effective measure in dealing with such contaminations particularly those from petroleum hydrocarbon sources; moreover bioremediation is emerging as a promising technology for the treatment of soil and groundwater contamination. Therefore the goal of this study is discussing the theory and practice of biological remediation of petroleum hydrocarbon contaminated soils and assessing the effects of operational conditions and parameters such as: temperature, dissolved oxygen concentration and pH on the removal rate of the target contaminant which is handled in the designed reactor. Due to large production and consumption rate of diesel fuel in Iran and many other countries, diesel fuel has been selected as target contaminant. In this study TOC and COD testing methods have been used to measure and assess the removal rate of the contaminant in the reactor. The experimental results indicate that, considering the operational conditions the indigenous microorganisms which have been separated from the soil are able to remove 50 to 83 percent of the contaminant after 30 days. Thereafter on the base of the results and considering the laboratorial specifications and conditions applied in this project, the optimum values of temperature, dissolved oxygen concentration and pH were respectively determined as 35°C, 4 mg/L and 7.

Disposal of chemical and toxic pollutants via industrial wastewaters into the environment has always been a hazard to water resources. According to scientific reports, biological systems are the most suitable method for treatment of such wastewaters. Obviously various effective organisms depend on the type of pollutants, treatment plant system and environmental conditions. Identification of the most effective microorganism is necessary for determination of optimum conditions, method of control and monitoring of bioreactor to access the maximum efficiency and improvement of operation. The objective of this study was to identify phenol degrader aerobe bacteria in combined biological phenol-treatment system of biofilter and activated sludge. Some amount of biological sludge was provided from domestic wastewater treatment as a primary source of microbe and was added to the designed reactor. Then samples were collected after growth of microbial mass. Phenol concentration and environmental condition (i.e. dissolved oxygen and pH) were stabilized after gradually adaptation of the system to phenol All samples were collected by sterile glass container. These samples were cultured on enrichment media and identified by various differential tests. dentification results proved phenol degrader bacteria are aerobe, nonfrementer but had negative result for of test with glucose as substra. These isolated bacteria were Pseudomonas aerginosa, P.alcaligenes, Moraxella sp, Acinetobacter sp, and Brevundiomonas vesicularis Because phenol was the only substrate and nitrogen and phosphorus as necessary factor in this system, all biodegrader bacteria used only Phenol as their both carbon and energy source. Phenol is degraded in a completely aerobic condition and dissolved oxygen concentration is sufficient since all the bacteria are aerobes.

This study was performed with the purpose of determining the efficiency of process of UASB (up flow anaerobic sludge blanket) in treating the wastewater of soft drink industry. The experiment was carried out during 8 months. The cylinder reactor dimensions were 170cm in height with 8 cm internal diameter and total capacity of 8.5 liters. The reactor was inoculated with a mixture of cow wastes, activated sludge of an industrial wastewater treatment –plant (Zam Zam factory) and the sludge of an anaerobic digester. The ratio for VSS/ TSS was adjusted at 0.63 , and the loading rate at startup was fixed on 1 kg COD /m3day loading rate .The Reactor was uprated and operated in mesophilic (24.8-38.2 ºC) temperature. The experiments then performed in three phases. The first phase of the study was carried out in four steps, the loading rate increased up to 2 kg COD /m3 .day at the constant COD concentration of 2000 mg/l. The efficiency of COD removal was found up to 78% in this phase. In the second phase, and the two steps the loading rate increased up to 2.8 kg COD /m3.day with an increase of COD concentration and 2500 g/m3 .At the end of this phase, the efficiency of COD removal was found to be 78.4 % and equivalent to 0.329 kg COD/kg VSS.day. The detention time was 21.4 hours. At the third phase and in four successive steps, the concentration COD and organic loading rate were increased to 3000 mg/l and 5 kgCOD /m3 .day respectively. At the end of this phase, the efficiency of COD removal was 78 % (equivalent to 0.389 kgCOD/kg VSS.day). The detention time at this phase was 14.3 hours and the linear velocity of wastewater flow was about 0.12 m/h .Finally, at the fourth phase of this study the pH of raw wastewater had been increased in few steps up to 10, in order to determine the effect of new conditions on efficiency of the process. The results show that the COD removal efficiency has decreased in the beginning of this phase but again increased to about 78% after adaptation had taken place.The gas generation rate was 0.15 m3/kgCOD removed. Considering the sludge formed in the top of reactor, it could be concluded that the sludge is  flocculant and pellet type.

One of the methods can be use in water quality management as a strong tool for decision making is Water Quality Indices. In this article the water quality indices for Karoon and Dez rivers were determined. Where there is less reaction to dicision or this reaction considered in local guideline and also at the times which there are adequate stations and enough sampling frequencies at the right stations, the use of BCWQI indice is recommended. However, when one or a few specific parameters are dominated on the decision and these parameters affect directly the infrastructure of sub-indices or total indices and also considering the effect of weighting rate on the reaction the use of NSFWQIm is preferred. The method of using OWQI is the some as NSFWQI with the difference of all parameters have equal value in decision making. The study was carried out during three years started from 2001 and statistical data were taken monthly.

A significant percentage of unaccounted-for water consists of leakage in water distribution networks in Iran. To detect leakage area with less costs and time spending and then identify the exact place of it with special instruments, would be economical and a better water resource management. In this research, a real case has been selected and examined with dynamic simulation using MIKE NET. The method that has been carried out in this research based on maximizing the correlation coefficient and minimizing the sum of error squares between pressure measured inputs (observed data) and calculated pressure (by model). According to the results, dynamic simulation of municipal water distribution system can be used as a guide to determine the place and the amount of leakage. There by the area of large leakage can be simulated with appropriate accuracy through measured pressure. There for from management aspect, dynamic simulation can be used to decrease time consumption and to save costs for detecting leakage.

Due to space constraints any access to a buried sewer conduit is seriously limited. In order to install the flow measurement devices, the space of manholes are the most appropriate places in a conduit. The conventional weir plates or sluice gates are usually used for flow measurements, however, these devices due to the nature of sewage, which contains sediments or floating objects are not suitable for flow measurements in sewer conduits. In a sewer conduit, the heavy solid particles tend to settle down behind a weir plate and floating objects accumulate behind a sluice gate, which both affects the accuracy of measurements by these devices. Therefore, the implementation of a combined system of weir-sluice gate at a cross section of conduit seems to be able to recover the defects of weirs and sluice gates. The application of this device in a circular cross section has not been received enough attention in the past. In the present paper the experimental results obtained from discharge measurement using combined weir-sluice gate system which allows simultaneously flow over and under a weir plate installed at the end of a sewer conduit are presented. The relationship between the experimental results and the theoretical flow which is a function of some geometric and hydraulic information of flow, are analyzed. Using statistical analysis of the obtained results of flow measurements accompanied with linear regression, an equation for discharge coefficient is proposed. The efficiency of the proposed technique is high enough that the associated error is limited to 10%.

There are more than tens of plating plants in Isfahan province. These units are operated as small and private or as a part of major plant. To determine pollution in return flow of these units, all of these plating units in Isfahan were monitored and sampled. In this research, 52 plating units were identified and investigated. The results show that 44.23% of units are located in urban areas, 28.8% in country-side, 15.4% in industrial zones and 11.5% in industrial towns. Among identified plating units, more than half of them (55.8%) were near industrial areas. The studied units maily used Nickel and Cadmium as main materials. The effluents discharged into septic wells, surface water, descent reservoirs and municipal networks in the rate of 78.3, 10.9, 6.5 and 4.3 percent respectively. In some units, there were few unusable septic wells due to overfilling with metal sediment. The overflow rate of discharge of plating process in studied units varied from 0.5 to 5.0m3/d depending upon type of plating process. The average discharge in these units was found 1.3 m/day. The concentration of zinc ion was in the range of 3.84 to 49.92 mg/l. The average concentration of nickel, chromium and copper were 3.85±2.2, 24.43±7.3, 14.51±15.2 and 14.22±10 mg/l respectively. The average concentration of cyanide was 0.012 mg/l. In this study, strategies for reducing discharge of these units and its pollutants and also appropriate sewage treatment to eliminate cyanide, zinc, chromium and copper are suggested.