Kenan Jijakli’s scientific contributions

Wastewater treatment plants generate large amount of solid wastes on a regular basis. These waste solids contain large amount of organic matter, nutrients and heavy metal. When disposed, these materials leach unwanted quantities of nutrients and heavy metals in the nearby water bodies. It subsequently, causes deterioration of aquatic and ecosystem health. Existing knowledge have focused on cost intensive options for disposal of these waste solids. For this reason, the ability to adopt these technological means was limited to large scale wastewater treatment plants. Due to lack of viable technological means, small and medium sized wastewater treatment plants dispose solid waste in an unplanned way causing harm to the environment. There had been significant focus given on the sustainable disposal practices of these waste materials in two decades. One of the growing disposal practices are land based application (e.g. fertilizer). However, the application poses concerns of contaminants from heavy metals and nutrients. Therefore, there appeared to be a growing necessity for finding appropriate technology to address the concerns related to leachability in sewage sludge. The objective of this project is to assess the applicability of alum treatment of waste solids for reduction of leachability in wastewater treatment residuals. The presentation will include current status of heavy metal and phosphorus leaching from sewage sludge. Aluminum has been observed to be a good binding ion for other heavy metals and phosphorus. Therefore, alum treatment of sewage sludge can provide the stability needed for controlling leachability. However, alum treatment can reduce the pH. So, lime addition can control the pH for the sewage sludge. The presentation will discuss the research approach to limit leachability of sewage sludge. The sewage sludge was collected from a municipal wastewater treatment plant in UAE. Initial tests revealed that the sewage sludge had pH of 6.8, indicating non corrosive nature of the sludge. The sludge has total suspended solids of 9500 mg/L and a water content of 99%. The sludge has been processed using alum and lime to form a stable surface area. The presentation will discuss the details of the batch and column tests that are currently being conducted.