Evaluation of the biosolids compost maturity in south Isfahan wastewater treatment plant

The composting process is a useful method of producing a stabilized material that can be used as a source of nutrients and soil conditioner. Maturity of compost is essential for its optimal use as a soil amendment and a source of plant nutrients as well. Immature composts pose problems of malodors and flies and phytotoxicity and pollution during use. Stability and maturity both are required for compost quality control. Compost maturity tests can be classified into physical, chemical, plant, and microbial activity assays. In this study, several methods of evaluating the stability and maturity of composted biosolids were compared based on chemical and biological properties. The sludge used of windrow composting was obtained from the drying beds of South Isfahan wastewater treatment plant. The results showed that, C/N ratio after 100 days of composting reached to 15/1; NH[4]/NO[3] ratio decreased with increase of the time dewatered sludge compost, which this loss is 57.3%. The content of volatile solids, 28.8% decreased with composting time. The number of fecal coliforms in the initial sewage sludge compost was 17.9 x 10[6] and at the end of composting was 898MPN/g of total solids and the compost process provided class A pathogen criteria. Use of chemical and biological parameters exhibited three phases: rapid decomposition [day 40], stabilization [day 80] and maturation [day 100] in biosolids compost. Thus, the biosolid compost was mature and ready for use as an agricultural substrate after about 100 days of composting

[Determination of corrosion and sedimentation potential in drinking water distribution system of Khorramabad city by corrosion indices and weight loss method]

According to the standard, drinking water must not be corrosive. Corrosive water solve primery materials of pipes, joints and valves in municipal water distribution systems and home plumbing systems and cause a lot of health, aesthetic and economic problems in water distribution systems. Thus, determination of corrosion potential of drinking water using methods which are feasible and reliable is necessary, and corrosion should be controlled in drinking water for water sanitation and health promotion among citizens. This research was carried out to determine water corrosivity or sedimentation potential in Khorramabad city, using corrosion indices. In this project 50 points as samples in two stages in the Summer and Autumn seasons were determined, and amount of corrosion indices, including Langelier Indice, Ryzener indice, Aggressive indice and Pokurious indice, corrosivity and temperature, calcium hardness, alkalinity, total dissolved solid and PH were calculated two times within a 3-month interval, then the data obtained from results were analyzed using SPSS software and statistical tests. Results of corrosion indices show that drinking water of Khorramabad is in equilibrium condition and has tendency to corrosion. Calculated corrosion indices are as follows: Langelier [-0.157], Ryzener [7.86], Aggressive [11.626], and Pokurious indice [7.65]. Statistical tests of Pearson and Spearman correlation coefficient don't indicate significant relationship between quality parameters with corrosion indices. Results of corrosion indices showed that drinking water of Khorramabad is inclined to corrosion

Chlorine residual efficiency in inactivating bacteria from secondary contamination in Isfahan, 2002

To investigate the inactivation of potential pathogens, we evaluated survival rates for Escherichia coli, Enterococcus faecalis, Aeromonas hydrophila and Salmonella typhi in samples taken from the Isfahan drinking water system. Chlorine residual, pH, temperature and total organic carbon levels were measured. The organism most sensitive to chlorine was A. hydrophila. It was inactived in < 100 minutes at chlorine levels of 0.11 mg/L to 0.90 mg/L. The other 3 organisms showed higher resistance. E. coli tolerated 0.30 mg/L chlorine for > 1000 minutes while Ent. faecalis and S. typhi survived at total chlorine concentration of 0.50 mg/L for 100 minutes. We concluded that total chlorine levels of less than 0.71 mg/L in water supply systems cannot provide the recommended safety levels

[Evaluation of wastewater treatment of detergent industry using coagulation procession pilot scale]

Surfactant or surface active agents are slightly soluble in water and cause foaming in wastetreatment plants and also in the surface waters into which the waste effluent is discharged. During aeration ofwastewater, these compounds collect on the surface of the water bubbles and create some problems in wastetreatment.In this study, surfactant, turbidity and COD in the industrial wastewater of the company, Paksan wasstudied. Study was done at pH ranging between 2 and 13 in a pilot scale process.The results showed that ferric chloride has higher efficiency in removal and it is possible to decrease thesurfactant, turbidity and COD.The efficiency of ferric chloride in coagulation process for removal of surfactant, turbidity andCOD from industrial wastewater is better than ALUM, Lime and Ferric Sulfate

Combined compost and vermicomposting process in the treatment and bioconversion of sludge

Traditional thermophillic composting is commonly for treatment of sludge. A related technique as vermicomposting process, using earthworms to breakdown sludge, is also becoming popular. These two techniques have their inherent advantages and disadvantages. The combined approach suggested in this study to enhance the overall process and improve the products qualities. Two systems,vermicomposting and combined compost vermicomposting processes, have been investigated in this study. The sludge used in this study was obtained from the drying beds of South Isfahan wastewater treatment plant.The sludge mixed with sawdust to provide C/N ratio of 25/1.Eisenia fetida was the species of earthworms used in the vermicomposting processes.The results obtained indicates reduction in the amount of volatile solids,total carbon and C/N ratio with the vermicompost age,which indicates the reduction in the biodegradable organic content and mineralization of sludge. Also increase in phosphorus concentration by the end process because of mineralization of organic matter. The results indicate that, a system that combines the two mentioned processes not only shortens stabilization time, but also improves the products quality. Combining the two systems resulted in a product that was more stable and homogenous; the product could meet the pathogen reduction requirements

Colour and organic removal from textile wastewater using water treatment wastes

Chemical treatment with coagulants has been recognized as one of the most effective methods of colour removal from textile wastewater In this study, the aluminum hydroxide present in the settled sludge from water treatment clarifiers was recovered as alum using sulfuric acid wastes from other industrial activities. The recovered alum was used in the treatment of textile wastewater in both forms of solution and suspension with mud. Its efficiency was then compared with those of commercial alum and ferric chloride. The results revealed that in textile wastewater containing disperse, acidic, ionic, cationic and direct dyes, the recovered alum suspension had a removal efficiency higher than that of the recovered alum in solution while both had higher efficiencies in removing dyes and organic matter compared to common coagulants available in the market [p<0.05]