Abstract
The biological slow filtration (BSF) system as a simple and efficient environmental technology has been widely applied in treatment of ‘micro-polluted’ water. At present, many related studies have focused on the removal efficiency of biological indicators (such as bacteria and viruses). However, there is less research on the removal performance of nutrients and organics in the BSF system. In this paper, we employed a lab-scale biological slow filter to study the removal efficiency and degradation mechanism of nutrients and organics. We proved through adsorption of filter layer at the early running stage and biodegradation at the later stage, the BSF system could achieve effective removal of NH3-N, TN, TP, CODMn and turbidity and the corresponding removal rates are 83.65%, 42.45%, 42.94%, 60.41% and 83.55%, respectively. Furthermore, we also explored the influence of four main factors (filtration rate, filter depth, hydraulic head and temperature) and their interactions on removal rates of nutrients and organics in the BSF system and obtained the optimal operating parameters as follows: filtration rate 0.1 m/h, filter depth 0.8 m, hydraulic head 0.64 m, temperature 26.06 °C. This study would provide a theoretical foundation for the actual application of biological slow filter in treatment of micro-polluted water in developing countries and offer an optimized basis for the design of operating conditions.
Highlights
In recent years, with the rapid development of industry and the acceleration of urbanization, the surface water pollution has become increasingly serious around the world [1] and generally presents a state of ‘micro-pollution’
From the 23rd day, the accumulation of NO3 -N decreased gradually and began to be negative, combined with the change trend of total nitrogen (TN) removal rate, we found that the denitrification rate tended to be stable when the biological slow filtration (BSF) system operated for 33 days and the corresponding removal rate of TN was about
dissolved oxygen (DO) inthe different filter layers, we could degradation mechanism of the typical pollutants in micro-polluted conclude that nitrification was dominated in the surface filter layer, which water source provide a theoretical foundation for the actual application of biological showed thatand there was a large accumulation of NO
Summary
With the rapid development of industry and the acceleration of urbanization, the surface water pollution has become increasingly serious around the world [1] and generally presents a state of ‘micro-pollution’. Considering the above factors, the technology of biological pretreatment or advanced treatment will be necessary in order to enhance effluent quality in the drinking water treatment process. Compared to the advanced treatment process (such as Ozonation, Membrane separation and Activated carbon adsorption), biological pretreatment technology has the advantages of lower maintenance costs and greater pollutant elimination in water source and has attracted wide attention. As an effective technology for biological pretreatment, has been widely studied and applied. Among all kinds of biofilter processes, the biological slow filtration (BSF) process is one of the most common and effective technique and has been used for the production of clean drinking water
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