Wastewater analysis for management in urban setting of Rawal watershed area

Rawal Dam is located in Islamabad to feed the drinking water requirement of twin cities. Rawal Dam water quality has been seriously deteriorated by rapid urbanization and draining wastewater into it. Therefore, a study was designed to estimate temporal and spatial impacts on wastewater quantity and quality. Bharakahu watershed area was selected to study freshwater supply and consumption, and wastewater disposal system. Wastewater flow and load was determined of selected 5 sub-catchments of the Bharakahu. Groundwater was the source of drinking water in 60% areas while water supply system was not satisfactory in 31 % areas. Wastewater disposal system consisted of pipe networks in 62% areas. In the study area, 90% people thought poor wastewater system was affecting ecological and public health. Total waste generated from Bharakahu was 6.35 MGD-1. Maximum wastes were being generated from Kiani Road Catchments (2.4 MGD-1) because it had maximum number of industries while minimum in Shahdara Drain Catchments (Before Bridge on Murree Road). When analyzed spatially Hathala Drain, it had maximum BOD and COD values which were 112 and 143 ppm respectively because the catchments were close with a large population. Nitrites were very high in Kiani Road Catchments with a value of 2 ppm because of a few hatcheries and poultry farms. Temporal analysis snowed that values of waste parameters were low during monsoon and high during non-monsoon because of high runoff during monsoon. Statistical analysis showed that the results are spatially non-significant, but temporally significant. Wastewater treatment options were analyzed and a criterion was developed which included costs (capital, operating and maintenance), technology, manpower, climatic requirements and community interactions, based on which the suitable wastewater treatment option was selected which was well-designed septic tanks.