Exploratory Study on the Performance of Newly Constructed Nablus West Wastewater Treatment Plant under Different Load Conditions

Nablus is the largest city in the north of West Bank. It consists of two catchments; western and eastern. therefore. Two wastewater treatment plants were proposed to treat Nablus wastewater. The western plant were constructed and operated, while the eastern plant is still under planning. Nablus-West Wastewater Treatment Plant (NW-WWTP) was designed to treat 3 million cubic meter of wastewater, where the produced effluent is planned to be reused in agricultural activities. Two challenges face treatment plant operators in Palestine: Lack of Information and skills in operation and maintenance of treatment plants, and the wide range variability of wastewater characteristics which received by the treatment plants. This thesis aims at studying the performance of Nablus-West Wastewater Treatment Plant (NW-WWTP) under different load conditions. This research depended on a computer model to simulate the operation of treatment plant. All input data such as influent characteristics, treatment plant processes,..etc. were collected from the concerned agencies. The computer program STOAT (WRC, 2010) was used to achieve research goals. One of simulation problems is the initial conditions of the treatment plant. Dynamic simulation was used to ignore those effects. The simulation period required 63 days (1512 hours) to reach the dynamic equilibrium. The modeled and studied cases were: performance of NW-WWTP based on the designer values, cases of some hydraulic equipment’s malfunctioning such as malfunctions of return activated sludge pumps, wastage activated sludge pumps, and completely one line malfunctioning. In addition, effects of variable pollutant loads from the most industrial activities in Nablus city on the treatment plant performance, were simulated and studied. The model was calibrated based on data received from the treatment plant laboratory. In case of exploring the performance of NW-WWTP by applying the design values for wastewater influents, the treatment plant expected to achieve about 98% COD removal, Nitrification to occur and 81% for ammonia were nitrified., total phosphorous in the effluent reached a value of 20mg/l without any changes on influent concentration. The treatment plant efficiency under the effect of malfunctioning cases varied from case to another. The worst case scenario expected to decrease to 61% COD removal. The efficiency of the treatment plant will varied from 63% during the olive oil season to 74.3% in the off seasons. Finally, a list of problems and their remedial actions were set in management plan to be employed for solving the problems that can occur due to the studied cases. One of the studied problems is foaming in activated sludge tanks that results in presence of scum on the surface of the aeration tank. One of the possible causes is the highly content of foaming agents and/or oils and greases in the incoming wastewater. The suggested remedial actions are: foam removal through water sprinkling and/or chlorine dosage. Another studied problem is the elevated concentration of suspended solids in the secondary clarifier effluent. The possible causes of this phenomena are: bad sludge settling characteristics, high overflow rate, or not properly functioning of the scraper. The suggested remedial actions are: to enhance the weir layout and eventually place some screen wind, or increase the sludge extraction and sludge recycle flow to aeration tanks.