Iranian Journal of Environmental Health Science and Engineering
Volume:1 Issue: 1, Summer 2004

Vertical or horizontal flow gravel beds can be used in water treatment as roughing filters. In order to improve the performance of horizontal flow roughing filtration (HRF) this process has been modified earlier by applying a constant coagulant dose prior to filtration named direct horizontal roughing filtration (DHRF). In this research a lab scale DHRF pilot plant was used for investigate DHRF performance. The study results indicated that DHRF (6.5 m long consisting of 2.5 m first compartment with 12-18 mm diameter grain, 2 m/s compartment with 8-12 mm diameter and 1.5m third compartment with 4-8 mm diameter) was systematically yielded good effluent quality (<2NTU, C.I=0.95) with raw water quality of 200-400 NTU. DHRF is a versatile pretreatment process capable of handling wide fluctuation in raw water turbidity (200-400 NTU) while operating condition such as coagulant dose [2mg Fe (III)/L], mixing intensity, time and filtration rate remained unchangeable.

The harmful substances, defined as trihalomethanes (THMs), were found to be formed during the disinfection of drinking water when chlorine was used as the disinfectant. In this research, the effectiveness of granular activated carbon (GAC) and air stripping (AS) packed column for the removal of chloroform (CHCl3) (as THMs basic indicator compound in many resources) in range of 50 to300µg/L, from drinking water was studied. Pilots of GAC and air stripping columns were designed and set up. The study was carried out for the two cases of deionized and chlorinated Tehran tap water. Also the effects of flow rate, chloroform and TDS concentrations were considered in both treatment systems. Gas chromatography (GC) with electron capture detector (ECD) was used for determination of chloroform concentration in inlet and outlet samples. The obtained data were analyzed by SPSS and non-parametric Kruskal–Wallis method. Results showed a positive correlation between the flow rate and chloroform concentration, and removal efficiencies. The average of variations of removal efficiencies for AS and GAC columns with deionized water samples were, 89.9%, 71.2% and for chlorinated Tehran tap water were 91.2% and 76.4%, respectively. The removal of feed residual chlorine in these columns with 0.5, 0.8 ppm was 100%, respectively and re-chlorination for finishing water was recommended. Results showed AS to be considered more effective in chloroform removal for conventional water treatment plants as a finishing process.

2, 4, 6 trichlorophenol (TCP) is one of the most toxic chlorophenols which is very difficult to biodegradation. Advanced Oxidation Processes (AOPs) is one of the most effective processes for degradation of persistent compounds. Since the mineralization of recalcitrant compound by AOPs often requires long reaction time and strong doses of oxidant, the combination of this process with biological one, is considered as an efficient and economic method. In this work degradation of 2, 4, 6 trichlorophenol in aqueous solution with Fenton reagent (H2O2 ê¢ë ion) was studied. The experiment was done in batch mode, and the initial concentration of TCP was 0.60mM. In pH=3, H2O2=1.8mM, Fe=0.6mM, more than 99% of TCP was degraded in 10 minutes after the reaction was started. Chloride ion generation as TCP degradation by product was investigated, and it was found that the scavenging effect of chloride is negligible. PH and UV215 absorbance analysis, after reaction completion, indicated that generated intermediates had the less chlorinated nature, acidic properties and nonphenolic structure. Chloride ion increases from 0 mg/L to 40 mg/L, pH decreased from 3 to 2.7 and UV215 absorbance decreased from 3.2 to 0.6, therefore it can be resulted that their biodegradability modified and their recalcitrance reduced. COD analysis indicated that TCP did not mineralize and in H2O2/TCP = 3 and oxidation time of 1 h, COD reduction was only 37%.

Recycling process is developed in communities to decrease the volume of high solid wastes and prevent environmental pollution. Plastic is one of the most recyclable materials in municipal solid wastes (MSW) with a high rate of application during the last decades. PET (poly ethylene therphtalate) is one of the basic plastic compounds which are used in a variety of products such as textile fibers, bottles and other containers. Methods for PET recycling include mechanical and chemical processes and PET incineration. In this study which was conducted on MSW analysis in Qom (a city in the central region of Iran, known for increase of population and high migration, environmental pollutions such as high quantity of MSW, industries and vehicle contamination, noise pollution and municipal sewage), physical analysis of MSW was carried out to four geographical sites and in different seasons of the year 2002. Results showed the rate of PET production to be 0.44% of the total MSW production, depending on site characteristics and area, time and cultural specifications. It is concluded that approximately 700 tons of PET plastics are buried per year.

Advances in microbial and biotechnology have given great impetus to the filed of pollution control. In some countries efforts are being focused on the application of biotechnology for wastewater treatment. Occurrence of microbial growth inhibitors in the biological reactor will affect their activity, which this in turn will lead to reduced performance of the system in pollutants removal. Restart up of the system, especially in the biological treatment of industrial wastewater, will require abundance time and cost. An effective solution to reduce these problems is to prepare and store dried concentrated sludge bearing the needed microorganisms to be used later. The most effective technique to produce such concentrated sludge is lyophilization in which a stabilized biological solid is produced through rapid freezing and then drying under high vacuum conditions. This study was carried out to investigate the lyophilization effect on the microbial quality of the activated sludge. In this regard, operational characteristics including OUR, SVI, soluble COD removal efficiency and predominant microorganisms species before and after lyophilization in a lab-scale experiment were used. The results showed that sludge lyophilization had no influence on microorganisms'' performance and operational characteristics of the activated sludge. In addition, there was not a significant change in the sludge properties before and after lyophilization. Sludge microorganisms were viable after lyophilization. So, lyophilization was concluded to be a suitable technology for preparation and preservation of cells in activated sludge because of preserving viability, ease of handling and simplicity.

Polycyclic aromatic hydrocarbons (PAHs) are one of the important groups of organic micro pollutants (Xenobiotics) due to their widespread distribution and low degradability in the environment (atmosphere, water and soil). Some PAHs exhibit carcinogenic and/or mutagenic properties and are listed by the United States Environmental Protection Agency (USEPA) and European Commission (EC) as priority pollutants. In this research three petroleum contaminated sites in Iran were selected in order to separate and classify PAH-degrading microorganisms. Samples were analysed for: soil physico-chemical properties, soil particle size distribution, Ultrasonic extraction of PAH (phenanthrene) and microbial analysis. Ultrasonic extraction method was shown to be a reliable procedure to extract a wide range of PAH concentrations from different soils, e.g. clay, silt, and clay-silt mixtures. Results showed that the extraction rate of phenanthreen in mentioned different soils was in the range of 85 – 100 percent. Results showed that two of three selected sites were contaminated with phenanthrene in the range of 10 – 100 mg/kg of soil, and had a reasonable population of PAH-degrading bacteria, which were enable to adaptate and degradate a concentration range of phenanthrene between 10 and 1000 mg/kg of soil. According to results, it can conclude that, the bioremediation of contaminated soils in Iran may be considered as a feasible practice.

Agricultural utilization of wastewater sludge is practiced in many parts of the world. Sludge may contain a variety of pathogenic microorganisms, which can spread diseases if there is human exposure to the sludge. Therefore, sludge must be treated before disposal and reuse. In this study the effect of liming on the microbiological quality of urban liquid raw sludge in Isfahan Wastewater Treatment Plant (IWTP) was investigated. Sludge samples were taken from IWTP, and the initial concentrations of total solids, volatile solids, total coliform, fecal coliform, Salmonella and ova of parasites were determined. Then adding lime to increase the pH of sludge to 11 and 12 and the effect of liming on the parameters was carried out after 2, 24, 72 and 120 hours. Salmonella was inactivated completely in treated sludge after two hours. The removal of up to 99% of fecal coliform was obtained for two ranges of pH. However, reduction of ova of parasites at pH 11 and 12 after five days were found only 56% and 83.8% respectively. Sludge treated with lime meets USA Environmental Protection Agency (EPA) standards regarding Class B and Class A after 2 and 24 hours respectively. At pH higher than 11 and 12 treated sludge with lime meets vector attraction reduction requirements after two hours. However, at a pH higher than 11 and 12 treated sludge with lime does not meet the guideline for pathogen reduction of class a regarding eggs of parasites.

In a three years period, 24 fossil fueled thermal power plants located in different parts of the country were extensively examined for discharge of pollutants into the environment and their potential effects on surrounding. During this investigation emission to air, discharge to receiving waters and land as well as electromagnetic fields were measured using relevant standard methods. This paper will focus on air pollution emissions and recent reinvestigation that was done after shifting the fuel from residual oil to natural gas. In our first studies that most of the plants were consuming residual oil, high level of SO2 emission in some areas was the main cause of losses to vegetations and fruit gardens. It was concluded that a serious problem threats the environment and health of people living near these areas. Based on the results some mitigation plans were recommended to the authorities, and after some times they started to shift to natural gas consumption. Our recent investigation that was after this action, showed a good improvement of air pollution reduction. This was almost 100% for SO2 and from 32 to 73% for NOx.

Different insecticides are being used for household and agricultural pest control in the capital city of Iran, Tehran. An investigation was carried out in order to evaluate the susceptibility level of laboratory and field collected mosquito, Culex quinquefasciatusin to different insecticides. Field strain was collected from sewage system of the city. Adult females were subjected to the diagnostic dose of different insecticides as recommended by WHO. Results showed that laboratory strains only exhibit resistant to DDT 4%, and susceptible to other insecticides. By using WHO criteria, field strain is resistant to DDT 4%, bendiocarb 0.1%, and tolerant to malathion 5%, permethrin 0.75%, deltamethrin 0.05%, lambdacyhalothrin 0.05% and etofenprox 5%. The field strain is still susceptible to cyfluthrin 0.15%.This findings indicate that routine use of pesticides in household and agricultural pest control may cause resistant in the wastewater mosquito, Culex quinquefasciatus.