The Study Of Anoxic-Oxic Hybrid Membrane Bioreator (HMBR) Treating Landfill Leachate

This paper is to study the efficient biological treatment processes combined with membrane filtration technology and then develop new treatment technology, aiming at the new published "Standard for Pollution Control on the Landfill Site of Municipal Solid Waste" (GB16889-2008) in 2008. The purpose of this technology is to reduce pre-treatment facilities and treatment load for subsequent advance treatment processing, to shorten the treatment scheme and then to provide a reference value for practical project in both theoretical and practical respect.The test consisted of two main parts, the anoxic/oxic-hybrid membrane bioreactor (abbr. A/O-HMBR) section and the comparative section studying on A/O-HMBR, A/OMBR and MBR. The main work of the first part was sludge acclimation and parameters optimization, in order to achieve good removal efficiency. Inlet requirements were given in the second section in view of RO inlet water requirements. The results showed as follow:After two months of sludge acclimation, the average removal efficiency of COD, ammonia nitrogen and total nitrogen of effluent from aerobic pond achieved 67%, 52.2% and 55.9%, respectively, and maintained stable. Under the condition of 0.84 kgCOD/m3d of COD volume loading, the average COD removal efficiency could reached 81.8%. When the ammonia volume load was 0.68 kgNH4+-N/m3d, the system could be running under good condition, and the removal efficiency kept 90%. In the case of 300% of reflux ratio, when the HRT kept 2.5 days, the removal efficiency of COD, ammonia nitrogen and total nitrogen reached 90.6%, 88.7% and 70.7%.This paper also systematically studied the removal of organic pollutants by membrane under various biochemical conditions of leachate, and the main results described as follows: (1) when BOD5/COD was between 0.45 and 0.72, the biological method contributed 78.2%~86.6% removal efficiency of COD, while interception caused by membrane contributed 7%~9.2%; (2) when BOD5/COD was between 0.23 and 0.37, the biological method contributed 56.3%~86.8% removal efficiency of COD, while the contribution of membrane interception was increased to 10.6%~16.8%; (3) if the leachate was directly treated by dilution and membrane filtration, without the biological treatment, the average COD removal efficiency by membrane interception reached as high as 90%, but possessed a more serious membrane fouling and short cleaning cycles; (4) the system showed a good treatment effect for ammonia with more than 80% of the average removal efficiency, while the membrane possessed no apparent effect on ammonia removal. In sum, with regard to the removal of ammonia nitrogen and total nitrogen, simultaneous nitrification and denitrification (SND) was found in the aerobic pond of this system and was discussed in details.Comparison of the three different processes, A/O-HMBR technology demonstrated higher removal efficiency than other two processes, especially in terms of ammonia nitrogen and total nitrogen removal. With regard to the requirement of RO process inlet water quality and used A/O-HMBR technology, the recommend COD, ammonia nitrogen and total nitrogen concentration for system influent was less than 3000 mg/L, 1700mg/L and 2300mg/L, respectively.