WATER AND WASTEWATER
Year:2005 | Volume:16 | Issue:2 (54)|Papers Count:10

The Latian Reservoir (70 Mm3) is located about 35 Km Northeast of Tehran and supplies drinking water to more than 2.5 million people in the greater Tehran metropolitan area. The main sources of water to the Latian Reservoir are the Lavarak River and the Jajrood River watershed which are becoming highly populated communities discharging their waste directly into surface waters.The results of a 3-years water quality monitoring show that this reservoir is in the eutrophic stage because of high levels of nitrogen and phosphorus concentration. Because of the phosphorus role in lake and reservoir eutrophication, in this paper several well-known models of phosphorus were compared and eventually Snodgrass-O’M Application of Phosphorus Simulation Models to Latian Reservoir elia phosphorus model was selected for long term phosphorus simulation in this reservoir. Decrease of phosphorus concentration in the Jajrood River is the most effective way for decreasing phosphorous concentration in the water body of reservoir.

A survey of wastewater characteristics in Kermanshah City was conducted to evaluate the range of pollutant ratios (BOD, SS, N, and P, to COD) that can be used to assess the robustness of wastewater management systems in terms of sustainability. The method of study is descriptive and analytical. Data were collected from three districts of the city that were socio-economically different (Ellaheiah, Taavon and Kasra) and considered to be true representatives of the population. Average values of BOD5/COD (0.58, 0.55 and 0.56 mg/mg); SS/COD (0.633, 0.619, 0.636); N/COD (0.09, 0.078 and 0.076); and P/COD (0.016, 0.015 and 0.018) were obtained from the three districts of the city, Ellaheiah, Taavon and Kasra, respectively. The alkalinity of the wastewater was 2.5 times stronger than normal wastewater. The results indicate that despite seemingly different values for the parameters measured, no significant differences exist among samples from the three study districts.  Based on BOD and COD, the samples seem to range from medium to strong. BOD/COD ratios are almost satisfactory (0.5 -0.6) in the sense that more than 0.55% of carbonaceous material is biodegradable. Regarding TKN, total phosphorous concentration is in the range of medium wastewaters. Phosphorous concentration in the wastewater from Kasra was significantly higher than those from the other two districts.

Bacterial colonization on metal surfaces and their metabolic activities lead to biocorrosion. In fact, any agent removing the biofilm or decreasing its thickness is capable of preventing biocorrosion. Biocides make up one such agent. These agents can control bacterial biofilms, remove these structures, or kill cells within them. The object of this research is to study the thermodynamic model of biocide penetration into the biofilm using the microtiter plate test. First, the biofilm bacteria were isolated to form a mix- bacterial biofilm. The biocide effect on the mix-biofilm was then determined using the microtiter plate test. Results from this test were compared with those from a thermodynamic model and it was revealed that the effects of oxidizing biocides such as sodium hypochlorite and hydrogen peroxide are in good agreement with the results from the model. The results indicated that increased biocide concentration leads to the removal of the biofilm or to the kill-off of the cells within it. However, in the case of non-oxidizing biocides such as sulfathiazole, glutaraldehyde, and alkyl dimethyl ammonium chloride, from the thermodynamic model such that increased biocide concentration did not remove the biofilm nor did it kill off the cells within it.

Starch is a plant polysaccharide with unique applications in Iran. Its increasing production and processing recently have led to large volumes of industrial effluent as an environmental pollutant. In this study, an amylase producing yeast is isolated and identified as "Cryptococcus aerius" to investigate some of its characteristics such as its amylase secretion and starch digesting patterns, kinetics of amylase complex, and its capability for carotenoid production in dual culture. The results indicate that C.aerius is capable of soluble and raw maize starch digestion and assimilation. Raw starch digestion is scarce among yeast species; hence, it is industrially important. C.aerius digests soluble starch in the first 10 hours of cultivation and on the basis of amylase secreting patterns, it is therefore categorized with fast growing species on starch as carbon source. Non-pathogenicity, digestion of raw starch, heat stability of the secreted amylases complex (>55°C), and the optimum pH level of 5.5- 6 for amylases complex are the set of properties that make this species capable of use in microbial production on an industrial scale. Absorption of carotenoid extract obtained from dual fermentation of C.aerius and Rhodotorula sp. indicates that the quality of carotenoids produced in dual fermentation is the same as that produced from pure Rhodotorula sp culture.

Ozone, as a powerful oxidant and disinfectant, has found wide applications in water treatment since early 20th century. A concentration level of 0.4mg/L for 5 minutes is considered to be sufficient for conventional disinfection in water treatment. The ozonation-chlorination process, with chlorine as a supplementary disinfectant, has been used since 2003 in phase 1 of Isfahan Water Treatment Plant with an influent capacity of 5m3/s. The object of this study is to determine ozone efficiency in decreasing total organic carbon, total coliform, and fecal coliform in raw water. In this study, 25 samples over the 3 months of study were collected from the influent, after both primary and secondary ozonation stages, and from the effluent from Isfahan Water Treatment Plant. The microbial test and total organic carbon (TOC) were measured. The results showed significant differences (p<0.05) between average values for TOC concentration and coliform and fecal coliforms in the influent, the primary ozonation, and the secondary ozonation but average values for the same parameters in the secondary ozonation and the plant effluent were not significant (p >0.05). The result obtained from this study revealed that the application of ozone as a disinfectant in the water treatment plant in Isfahan is not adequately efficient and that final chlorination may, therefore, be necessary.

Aerated lagoon is a kind of the aerobic suspended growth process that can be used to treat domestic and industrial wastewater. Due to its considerable design flexibility, the aerated lagoon has gained wide applications in both developed and developing countries. This study aims to investigate the performance of aerated lagoons in the wastewater treatment plant in Bou-Ali industrial zone in Hamedan over a period of seven months from May to November 2004. Quality indexes such as pH, TSS, BOD5, COD, total coliform and fecal coliform, Cu, Pb, Zn, total Cr in plant influent and effluent were determined. The average values of pH, TSS, BOD5 ,COD, total coliform and fecal coliform, Cu, Pb, Zn, total Cr in plant effluent were measured to be 7.46, 84mg/l, 76mg/l, 176mg/l, 1.98´104 MP N /100ml, 3.31´103 MPN/100ml, 0.04mg/l, 0.13mg/l, 0.88mg/l, and 0.03mg/l, respectively. The removal efficiencies recorded for the contaminants studied were 73.56%, 91.58%, 89.95%, 99.968%, 99.713%, 62.24 %, 59.08%, 56.51%, 62.57%, respectively. Total and fecal coliform contents were greater than standard limits for irrigation recommended by Iranian Environmental Protection Organization while the rest were below the standard values. If the effluent from this plant should be reused for agriculture or landscape irrigation, reduction of microbial pollution to standard limits recommended by Iranian EPO or to guidelines set by WHO must be considered.

One of the conventional problems in frequency analysis and prediction of various hydrologic events is lack of long time records of such events in gauging stations. This problem together with inaccurate at-site estimations has caused increasing application of regional methods for such procedures. In this study, the above mentioned method was used for selection of parent distributions to fit maximum monthly rainfall data of 18 sites in the Zayandehroud basin and, consequently, the GEV distribution was selected to estimate the related parameters and quintiles.

Potentially mineralizable nitrogen (PMN) can be usually considered as labile nitrogen. Measurement of PMN is expensive and time consuming; therefore, a simpler and more rapid alternative may facilitate routine laboratory analysis. The objective of this study was to determine the relationship between PMN and biological index of nitrogen availability (BINA). The studied soil was previously treated with 0, 25, and 100 tons ha-1 of sewage sludge with 0, 1, 2 and 3 consecutive years of application. Soil samples were taken 6 months after the latest application. PMN was measured according to Stanford and Smith procedure (20 weeks of aerobic incubation with 2 weeks leaching intervals) and BINA measured as described by Bundy and Meisinger (7 days of anaerobic incubation at 40° C followed by extraction of NH4+). Results showed that PMN was significantly correlated with BINA (r=0.938, P<0.001) in sewage sludge treated plots and that BINA can be considered as a more reliable index for estimation of PMN. The results showed that BINA might be used as a simple and rapid method to evaluate PMN in sludge amended calcareous soils.

Climate variability is the main reason for drought and water scarcity. Annual rainfall trend was investigated in arid and semi-arid regions of Iran using 79 climatology and synoptic stations with 36 years of data records. Monthly and annual precipitation data from homogeneity tests were applied and discontinuities were adjusted in non-homogeneous stations using the annual nonparametric Mann-Kendal statistic test. The results showed no evidence of climate change in the study area. Although many stations showed negative trends indicating decreasing precipitation, this trend was not statistically significant at 95 percent significant level. The results indicate that the southeastern part of Iran has recently experienced a climate change of negative precipitation trend. Mapping trend statistics did not snow any geographical orientation. Considering the global warming and using temperatures, evident in the study area, the adverse effects of decreasing precipitation on temperature, the adverse effects of increasing precipitation in conjunction with significant positive trends m temperature rise may lead to severe ecological and economic problems in the study area. The frequently occurring droughts in this region can be due to increasing temperature and decreasing precipitation.

The present work describes studies on the sorption of fluoride ions from water by titanium compounds used in water treatment to reduce fluoride content in water resources. There are different methods of reducing fluoride ion in water, each associated with specific problems such as secondary contamination, environmental contamination, high costs, or the need for primary and secondary treatment. In this study, application of titanium sulfate and Metatitanic acid produced from titanium ore concentrate (ileminite) is investigated in the removal of fluoride ion and the possibility of complete purification of fluorine containing wastewater is examined to determine the optimal conditions. Metatitanic acid has a great sorption property for fluoride ion. Also titanium sulfate is a suitable and more effective material for this purpose. Efficiency of this material in reducing fluoride ion content is 99.9% and it is possible to refresh sorbet material for reuse without problems arising from T+4 ion contamination.