Pretreatment of municipal wastewater by enhanced chemical coagulation

The efficiency of existing municipal wastewater treatment plants has been affected by the increase of incoming organic load caused by the expansions in developing countries. In the present investigation, the effect of Chemically Enhanced Primary Treatment [CEPT] process was studied on the enhancement efficiency of a municipal wastewater treatment plant in Tehran, Iran. Jar test results showed an increase in COD, phosphorus, turbidity and TSS removal by the increase in dosage of aluminum sulfate and ferric chloride as coagulants. Results revealed COD, phosphorus, turbidity and TSS removals of 38, 66, 68 and 69%, for alum at 80 mg/L and 60, 73, 49 and 48% for ferric chloride at 70 mg/L as the optimum doses, respectively. Ferric chloride revealed more efficient results compared with alum. The result of tests to find the optimum pH of two coagulants revealed that pH of 8.2 for both chemicals is the optimum performance condition. Therefore, CEPT can be used as an efficient method in conventional municipal wastewater treatment plants to reduce the organic load of biological treatment and enhance the removal of nutrients

Evaluation of navab regeneration project in central Tehran, Iran

Urban design has been used in the cities throughout the world to achieve certain goals and purposes. It has been common in developing countries, including Iran, to use urban regeneration plans in the older sections of large cities to eliminate urban blight and decay, and eventually achieve modernization and in some cases to also overcome socio-economic and cultural problems. Approaches have been used are modernist, technocratic, and elitist type of design/ decision-making, which, as, the present case study show, results in complete failure. This study intends to, following a discussion on theoretical basis of the issue, through a post-construction/ post-occupancy evaluation of the Navab Regeneration Project in central Tehran, explore the reasons behind this failure and see how the problems involved in the product may be construed to the kind of design/decision-making process applied