Volcanic rock double-layered filter media aeration biological filter pools are treating urban domestic wastewater. In recent years, with the rapid economic development in China, major and minor rivers across the country have been affected by varying degrees of pollution. Urban domestic wastewater has gradually replaced industrial wastewater as the primary source of water pollution worldwide. The reuse of urban wastewater not only alleviates water pollution but also provides a stable water source for cities, easing the situation of water scarcity. This is particularly significant for cities in northern China.
Conventional treatment processes are inefficient in removing organic matter and ammonia nitrogen from water. Moreover, the intensification of chlorination processes itself leads to the formation of organic halogenated compounds, which pose greater health risks. Therefore, seeking a species-specific, practical, and cost-effective water treatment method holds significant practical importance. Water treatment biotechnology is an economically viable and toxicologically sound water treatment technique, with the aeration biological filter process being particularly advantageous due to its small footprint, high volume load, high hydraulic load, short hydraulic retention time, low construction costs, and excellent treated water quality. Its application potential is vast.
This study employs a zeolite-volcanic rock double-layered filter media aeration biological filter to experimentally research the treatment of domestic wastewater from Lanzhou University of Technology. Upon achieving a stable removal rate of approximately 60% for COD_(cr) and NH_3-N in the water quality, it is deemed that the biofilm has successfully attached, and the experiment enters the operational phase. During the operational phase, the study conducted tests by altering gas-water ratios, detention times, and operating loads, focusing on the removal of pollutants such as NH_3-N and COD_(Cr) from urban domestic wastewater. The results indicate that the zeolite-volcanic rock double-layered filter material performs well in wastewater treatment. Under conditions of a gas-water ratio of 2:1, a hydraulic detention time of 20 minutes, and a water temperature of 16-24°C, the removal rates for NH_3-N, COD_(Cr), turbidity, and phosphorus are 95.8%, 85.5%, 97.4%, and 22.3%, respectively. A comparison with a single-layer filter media aeration biological filter under the same conditions revealed that the double-layered filter material performed better.
Wastewater passes through a filtration layer, capturing pollutants in the water while being biodegraded and converted by the filter material. Dissolved specific substances and organic sludge are retained in the filtration layer, allowing only purified water to pass through. This achieves complete biological treatment within a closed reactor without the need for secondary sedimentation, which is the principle of an aeration biological filter.
