Iranian Journal of

Backgrounds and Objectives:Safe drinking water providing is one of the main purposes in the community. Development and improvement of community is related to the public health. In this study !we studied the bacteriological quality of 116 villages under coverage of the water and wastewater companies in rural areas of Saqqez in.1386
Material and Methods:Drinking water of these rural areas have provided of deep, semi-depth- wells and spring water sources. Because in numerous rural areas both sources of drinking water and in some of them different sources of drinking water were used (old and new storage water source), in general, 359 samples were collected and transferred to the laboratory for testing to evaluate its quality. We also used linear Regression statistical analysis for collected data.
Results:results show that residual chlorine in drinking water in 33.88 percent of rural areas population were in range 0.2-1 mg/l. For 98.3 percent of the seqqez rural population, the turbidity was lower than the maximum permissible levels of drinking water standards of Iran (5 NTU). There was no any E.coli contamination in 88 percent of drinking water in saqqez rural areas.
Conclusion:Based on WHO guidelines concerning the microbial quality of water published in 2006! the average indicator for lack of E.coli in water of rural areas of seqqez was 88 percent and water is safe or good for drinking.

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 plant
Materials 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.

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, 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.