Phosphorus Removal In Airlift Reflux Combos Construction

The promotion of urbanization has greatly improved people's living environment, but at the same time, it also turns the pollution sources which can be removed by natural purification process to be many decentralized pollution sources. And these decentralized pollution sources can't be brought into centralized treatment systems. This gives birth to the decentralized wastewater treatment, which is an effective and necessary complement of centralized sewage treatment. Airlift Reflux Combos Construction is a kind of reactor designed for the decentralized domestic sewage treatment, which is composed of influent zone, anoxic zone, aerobic zone, gas lift reflux zone and settling and effluent zone. Airlift Reflux Combos Construction has a compact structure, occupies less place, needs less operation fees, and its operation and maintenance are simple. Thus, it has a universal applicability for the regions under different economic development levels. The device has a good performance for organic matter and ammonia nitrogen removal. However, the ability to remove other pollutants has not been further studied.In the process of the detection of total phosphorus in the system, the concentration of total phosphorus in effluent was lower than that in influent. That is, the system has an ability to remove phosphorus. At present, phosphorus removal methods mainly conclude the traditional microbial phosphorus, animal and plant absorption, adsorption, and chemical precipitation. There are also another method, phosphate reduction mechanism, which is still at an early stage of experimentation and investigation. Based on the phenomenon of phosphorus removal in Airlift Reflux Combos Construction?ARCC? in pilot scale, combined with the review of the basic theory, Airlift Reflux Combos Construction as the research object, treating domestic wastewater, removal efficiency and removal ways of phosphorus of ARCC was explored. This was down in order to further improve the pollutant removal performance of the reactor, and make it easy to popularization and application of the reactor.The total effective volume of ARCC in pilot scale was 10.31m3. in the operation period from 10 in 2014 to 10 in 2015, the DO was 0.5-2.0mg/L, while reflux ratio was 0.6¹.0, the influent average flow rate?551±94? L/h, phosphorus concentration in influent?4.628 ± 0.966? mg/L. Under the conditions mentioned above, the main conclusions were as follows:1) The average phosphorus removal efficiency of the system was?44.629±8.646? %, and the average phosphorus removal amount was?27.120 ± 8.258? g/d.2) The main phosphorus removal ways of the system mainly includes the accumulation of sludge, animal feeding and phosphate reduction mechanism. The phosphorus amount removed by sludge accumulation was 8.218g/d, which accounted for 30.30% of the total amount removed in the system. The accumulation amount of total phosphorus in the anoxic zone is 5.834g/d. the accumulation amount of total phosphorus in aerobic zone and the settling zone are 2.384g/d. From the small to the large, Res-P, Ca-P, BD-P, H₂O-P, Org-P and Na OH-P in sludge account for 6%, 6%, 9%, 15%, 23% and 41% respectively of accumulation amount of phosphorus by sludge. The removal amount of phosphorus by animal feeding was 0.795g/d, which accounted for 2.93% of the total phosphorus removal. And phosphorus removed by mosquitoes can't be estimated. Phosphorus loss is 18.107g/d. The average content of anoxic sludge MBP to?0.70 ±0.58? mg/kg, content of MBP in aerobic sludge is up to 4.81mg/kg. It's inferred that phosphorus loss is the results caused by mechanism of phosphate reduction. That is, phosphate is reduced into phosphine and releases into the atmosphere in gaseous form from the system. The phosphorus loss may also include the phosphorus carried by insect which has left the system.3) The phosphorus removal efficiency decreases with the increase of influent flow rate, and is not related to the flow rate of the anoxic zone. When influent flow rate is?320⁷30? L/h, the phosphorus removal amount increases with the increases of the influent flow rate and the flow rate in the anoxic zone. And when the return of nitrate nitrogen content?QrNO₃^--N? is equal to 215g/d, the system has the largest amount phosphorus removal. When QrNO₃^--N<215g/d, removal amount phosphorus increases with the increase of QrNO₃^--N, while QrNO₃^--N>215g/d, it decreases with the increase of QrNO₃^--N. The phosphorus removal amount is affected by the carbon removal amount in the anoxic zone?RAC?, and increases with the increase of RAC. The increase of effluent turbidity can lead to the increase of the total phosphorus content, and phosphorus removal efficiency is reduced.