Supports Delivering Sustainable Environment Using Drinking Water Treatment Plant Waste for Sullage Treatment: Box–Behnken Design Model for Process Optimization

Abstract:
Currently, a great attention has drawn by the academic world and industry to safe the environment. In Egypt, large amounts of by product waste, namely alum sludge (AS), is generated from the drinking water treatment (DWT) plant that must be discarded. A recent trend in such sludge management is transferring it to a valuable resource which is critically provides the environmental protection and sustainable development. On the other hand, sullage (graywater) wastewater is produced as a domestic wastewater that does not contain the toilet effluent. A crucial issue is to find a low-cost adsorbent for treating this waste for its final disposal or reuse. This study investigates the opportunity of integrating water treatment plant sludge waste into an adsorbent material. The main goal is converting sullage for non-potable purpose focusing on alum sludge adsorbent that is simple and economical adsorbent. Primarily, the collected alum sludge is dewatered and prepared as an adsorbent material. Moreover, the wastewater is subjected to the adsorption process after the sullage is exposed to a physical pre-treatment. A response surface methodology involving an experimental design was used to optimize the effects of sample stirring, pollutant load and adsorbent dosage on sullage waste treatment and obtained the optimum value of the three process variables. The adequacy of the model was verified effectively by the validation of experimental data. Additionally, the optimum results show that the sullage treatment is reached to 60% removal after 2 h of reaction time. The results presented that the drinking water plant sludge could be used in sullage treatment, helping in reducing both the impacts of water treatment plants and domestic sullage for further usage.