WATER AND WASTEWATER
Year:2004 | Volume:15 | Issue:2 (50)|Papers Count:8

This paper provides an overview of the hydrology and water use in the Zayandeh Rud basin based on the data available over the 11- year's period 1988-1998. The inflows into Chadegan reservoir, the releases from the reservoir, and the extractions along the river for irrigation and other purposes are considered, and a rapid water balance of the basin is performed. Inflows to the Chadegan reservoir, which serves to collect and regulate the runoff from the upper catchments of the basin to better meet the downstream water requirements for irrigation, urban and industrial uses, follow a regular pattern with moderate variability. But the limited year-to-year storage in the reservoir makes the basin vulnerable to prolonged periods of drought. Water releases from the Chadegan reservoir also show a predictable pattern, with the only deviations occurring during flood events. There is a high reliability of meeting the water requirements during periods of peak demand. But releases during the winter months, at the end of the irrigation season, are lower and more variable. This results in low discharges in the Zayandeh Rud and reduced water quality, especially in the lower reaches of the river. A simple water-balance approach was used to estimate the proportion of return flows in the basin. An average annual value of 30% was obtained, with the magnitude of return flows being particularly important in the lower reaches of the basin. But more investigation, especially including groundwater and water quality aspects, needs to be carried out before a definitive value can be advanced. Given the limited supply of fresh water in the Zayandeh Rud basin, further water resources development and water management improvements can only be envisaged in there is scope for real water savings in the basin. This can be assessed if a basin-wide approach, leading to a good understanding of water use (and reuse) at the farm, system and basin levels, is adopted.

Rapid sand filter is one of the most important units in the water treatment plants. It has some difficulties in operation such as backwashing. For the solving of this problem a rapid sand filter has designed and built with the self-cleaning backwashing system. This system consists of 3 main constituents; one galvanized siphon and two galvanized steel tanks. One of them is used for filtration and the other used for the storage of filtrated water in elevation for backwashing the system. Water enter from upside of the filter through the inlet pipe, and collected from the under drainage pipe. Then filter water conduct to the storage tank and exit from outlet pipe. In the beginning, the head loss was low, but because of bed clogging by suspended solids; it increases gradually to the designed head loss (1.2m). Then the system is outed of the service automatically and the backwash is began. The main data for the design of system selected from the hydraulic rules of siphons and rapid sand filter criteria. After essential calculations it was constructed and was started operation. For the hydraulic studies a known volume of storage tank was selected and the time needed for the fill (in filtration stage) and empty (in backwash stage) of water volume with volumetric method were measured.In hydraulic studies the filter surface rate (SOR) was selected about 5-7.5m3/m2/hr (1.39-2.08 lit/sec) and the flow of water in siphon, during the backwashing was measured 8.7 lit/sec. It can be seen that the siphon passes 4-6 times the inlet raw water thus a negative pressure will created in the siphon which causes the water above the sand bed to be discharged automatically and rinse water from elevated tank flow under the sand bed and back wash it.So according to this study self cleaning rapid sand filter is very useful for water filtration, especially in small population community. The construction of system is rapid, simple and economic.

Petroleum refineries generate large amounts of wastewater with high concentrations of hazardous contaminants. The conventional treatment method is a biological treatment process preferably the activated sludge system. In this system some organic compounds can be toxic or inhibitory to some organisms above certain critical concentrations and cause the growth rates to decline, such as Toluene and Phenol. There are also accelerating materials to improve the biological treatment efficiencies, such as Methanol, Glucose etc. In the present work the effects of Phenol, Glycerine and Maltose on the performance of the process were investigated. The Phenol concentrations up to 100ppm did not show any inhibitory effects on the COD percent removal; however higher concentrations reduced the process treatment rate. Glycerine concentration. Between 0-200 ppm caused increase in COD removal from 57% to 79%. Maltose gave similar results to Glycerine which has been fully discussed.

Using of organic waste resources especially municipal wastewater sludges for improvement of agricultural soils’ fertility is increasing, but in order to decrease environmental and health risks sludge must be stabilized before using in farms. Nowadays, vermicomposting process has been considered for stabilizing organic wastes. As, there is contravercial reports about concentration of nutrients (P,.K.N), organic matters and C/N ratio in vermicomposts, this research study is performed to determine concentration of nutrients organic matters and C/N ratio in vermicomposts derived from municipal wastewater sludge The concentration of nutrients in manure and vermicompost was compared with each other.Eighty five percent of dewatered raw sewage sludge and %15 bulking agent were mixed to provide earhworms’ food for a one month period. Concentrations of volatile orgainic matters, total nitrogen, total phosphorous, total potassium, Ash and pH in initial substrate and vermicomposted sludge were determined by dry agitation, macrokageldal, colorimetery, flamephotometery, Gotas, modifled Burian and Erhart methods, respectively. Concentrations of organic matter, nitrogen phosphorous, potassium, pH and C/N ratio in vermicomposted sludge were %36.42, %1.04, %0.11 , %0.62, 7.5 and 22.62 respectively. The obtained vermiocompost is a suitable organic amender for fertilizing of agricultural soils.

During 1994 to 1999 a research program titled "A qualitative and quantitative review of industrial wastewater in Tehran province" was done. This article presents the most important results obtained from this study. The research covered 330 food, textile, chemical, and Materials (Metal and liquid materials) factories. Completing of the questionnaire, sampling from the wastewater and analyzing have been done for 5 years. The results show that completely wastewater treatment in food, textile and metal industries were done in 8%, 18% and 17% of units respectively. In chemical industries for major groups include pharmaceutical, soap and detergent, pulp and paper, and paint industries were studied. In pharmaceutical and pulp and paper industries, there were only one factory in each group which were doing a complete treatment, and in detergent and paint industries there were no complete treatment at all. Maximum discharge of wastewater in food and textile industries was into surface waters. They were 62.4% and 48.8% respectively. But mainly wastewater discharging in metal and liquid materials industries were into ground waters which were 86% and 83% respectively.

This study is an attempt in groundwater modeling of Ab-barik aquifer (Bam, Iran), in order to asses the artificial recharge project and the future situation of the aquifer. Studies show that the discharge of the aquifer has exceeded the recharge, especially during the 1980-1990. The water table in March 1985 has dropped about 10m as compared with March 1973. Studies indicate that the drawdown of the free surface will continue in the future so that in March 2004, the drawdown will be about 18m as compared with the March 1973. Also it was found that despite the artificial recharge of the aquifer (started in 1996), the drawdown has been continuing. Modeling has showed that artificial recharge project has caused 12.6 mm3 recharge into the aquifer annually, during 1996-1999.

This paper reviews the recent advances in the development of ABR, which is one of the new types of anaerobic reactors capable of handling different kinds of industrial and municipal wastewaters. This reactor consists of some compartments in which environmental conditions such as pH and temperature or toxic material are stabilized in first compartment. Therefore, methanogenic bacteria that are very sensitive to environmental conditions can grow easily in the next compartment. An important property of this reactor is the low hydraulic retention time (HRT) of wastewater that reduces the reactor volume and increases solid retention time (SRT). Also, the reactor is more stable to hydraulic and organic load shocks and there is no need to gas-solid separation devices. There is indeed, ability to separation of methanogenic and acidogenic phases. Economical studies show that these systems are also cost effective. The ABR reactor has shown good performance in the treatment of low strength and low temperature wastewater and those containing sulfate.

This research was performed to elicit the distribution of sewers diameter in terms of population by means of information collection via consultant engineering and urban water and wastewater engineering companies. Based on obtained data in the cities with population fewer than 100/000 the highest percentage of diameter distribution was 79.12% for 200mm pipe and the lowest was 0.06% for 900mm pipe. In the cities with population between 100000 and 500000 the highest percentage of diameter distribution was found 56.67% for 200mm pipe and the lowest was 0.12% for 900 mm pipe. In the cities with population of 500000 and more the highest percentage of diameter distribution was 59.67% for 200mm pipe and the lowest was 0.19% for 900mm pipe. Without population factor the highest percentage of diameter distribution was 60.73% for 200mm pipe and the lowest was 0.131% for 900mm pipe.