Development of Biofilter Devices for Nutrient Removal From Wastewater

摘要

Nutrient pollution still remains one of the greatest challenges to water quality contributing to harmful contaminations water sources, and costly impacts on the economy.This review considers the development of the biofilters,focusing on the design features that have the most influence on their technical and economic performance.Modern biofilters,based on SAF technology,are particularly suitable for sewage treatment works with throughput rates up to 1,000m3/d.The main advantages of SAF plants include high quality effluent,low power usage and small footprint.A wide range of filter media are available for different designs,which could be configured for both aerobic and anaerobic treatment in BOD and/or ammonia reduction applications.The two most important parameters for filter media are their Specific Surface Area (SSA,m2/m3) and Void Fraction (percentage of void volume or porosity).However,due to the risk of clogging by suspended solids or excess sludge the media used for this application should be limited to about 500m2/m3.In tertiary treatment or river restoration applications where the influents tend lack any readily biodegradable substrates, SAF design provides the most appropriate choice for further development to produce effluents with very low nutrient levels.