Assessment of performance and greenhouse gases emissions for aerobic biofilm combined reactor

Abstract

Most of the existing sewage treatment plants (STP) in Malaysia are using conventional systems with poor treatment effects, which causes the STPs to become one of the main sources of water pollution. This study aimed to design a novel biological water purification system with a combination of a fixed biofilm reactor and a moving bed biofilm reactor termed as the aerobic biofilm combined reactor (ABCR). The ABCR system has not been reported to treat domestic wastewater apart from industrial wastewater, and no research has been documented on the performance of greenhouse gas (GHG) emissions, power consumptions and space occupation of ABCR system. The objective of this study was to characterize the performance of ABCR and to verify its local adaptability, efficiency, economic and environmental impacts in treating the domestic sewage in Malaysia. Different water intake rates were adopted to verify the system resistance to the fluctuation of organic loading rate, and 10 h was selected to be the designed hydraulic retention time (HRT). This HRT was the minimum HRT to meet the local effluent discharge standard. The power consumption to run the ABCR system was also analyzed during this study, and the results showed an average value of 0.287 kWh/population equivalent. The ABCR system was also compared with the conventional sewage treatment process of extended aeration (EA). The results showed that the ABCR system offered the cobenefits of a higher quality of treated water, greater space saving (51.2 %) and lowered GHG emissions (18.3 %) than that of the EA system. The performance of ABCR system under the selected HRT also showed that the system is suitable for the typical Malaysian domestic sewage treatment to comply with the local discharge standard. The effluent achieved well below the discharge limits for most of the major pollutants, especially on the removal of ammoniacal nitrogen. The ABCR also has a lower power consumption (saving of 21.4 %) and lower sludge generation (85.7 %) as compared to the EA system. The ABCR system could promote the sustainable development of municipal facilities for urban wastewater treatment.