(167c) Using a Wastewater Process Model to Evaluate the Effect of Mixing Cooling Water Blowdown (CWBD) on the Performance of WWTP: A Case Study

District cooling systems in Gulf region are generating huge volumes of cooling water blowdown (CWBD) that is typically rich in chemicals and contaminants. Cooling water blowdown was previously dumped straight into surface water bodies and never been treated or reused. Discharging CWBD blowdown water can cause several environmental problems. Due to the dangerous nature of the disposal options, other sustainable options are explored. The kind and quantity of contaminants present in CWBD differ from one system to other and influenced by a variety of variables. For example, the source of the cooling tower's input and make-up water has a significant influence on the presence of various pollutants. Chemicals employed for treatment, as inhibitors, or even as anti-corrosion inside the towers, can have a significant impact on the chemical makeup of the water. Some contaminants are typically seen in CWBD samples such as high TDS, high metal content, low biodegradability, and the presence of chemicals such as calcium, sulfates, silica, phosphates, are some of the most common concerning contaminants in the study of CWBD characteristics. This paper will study the possibility of discharging CWBD into already functioning wastewater treatment plants rather than building a treatment plant exclusively for blowdown. The effect of CWBD on wastewater treatment plants that employ a biological reactor will be explored. Doha North Wastewater Treatment plant (DNWWTP) was considered as the case study and the plant was simulated using GPS-X for theoretical results. The main concern is that the contaminants present in CWBD will have an adverse effect on the biological reactor. Mixing different percentages of CWBD with the wastewater influent in the GPS-X model showed no adverse effects on the performance of the biological reactor nor the overall systems removal efficiency of the plant. 5%, 10% and 20% v/v CWBD was taken into consideration for the study. The biodegradability, effect of adding CWBD in the influent if WWTP was performed using BOD tests & organic matter measurements for 5 days. The toxicity and inhibition effect of CWBD were measured in 5 identical ASR each mixed with different % of CWBD The lab-scale results, biodegradability, toxicity and inhibition tests as well as GPS-X results conclude that mixing CWBD up to 20 v/v% ratio with the WWTP effluent has no effect on the performance of the process nor develop inhibition/ toxicity or salt accumulation.