The wastewater treatment plant in Islamabad, Pakistan, was studied to see how well it was working. The plant was not doing a good job breaking down waste, especially in terms of BOD and COD. The operators were not keeping the sludge in the tanks for long enough, which was causing problems. By adjusting the sludge retention time, the plant's performance improved. It's important for the operators to know how to manage the sludge properly for the plant to work well.