The Treatment Of Landfill Leachate With High Salinity Using AF-MBBR And Specific Halotolerant Bacteria

The coagulation and ammonia nitrogen blow-off were carried out first by static experiment in laboratory for the pretreatment of landfill leachate. The treatment conditions of coagulation were as follows: LanQing coagulant was used here, and with the adoption of 0.5mL saturated solution in 1L leachate, pH value ranges from 5.5 to 6.5, an effect of 30% COD removal was reached. The result of ammonia nitrogen blow-off experiment showed that under the condition of water temperature 20.6℃, pH value 10.8, and the blowing period 4h, the ammonia nitrogen removal efficiency was 80.8%.Considering the high-salinity, high-toxity, hardly-biodegrable characteristics of Dagang Landfill Leachate, the biological treatment was carried out by using a combined biofilm process of Anaerobic Biofilter(AF) and Moving Bed Bioreactor (MBBR). The experimental result indicated that, biofilm reactor can keep a high concentration of biomass, which avoided the problem of sludge flowing away in activated sludge process, so as to maintain a better treatment effect. The operational condition obtained is as follows: for AF, with a 10 hour's HRT, the load range for the best treatment effect is 4~5kgCOD/ (m3?d), and for MBBR, the load range for the best behavior is 3.38~5.75kgCOD/ (m3?d) with a HRT of 10h. Under the abovementioned treatment situation, and after a period of appropriate method of biofilming acclimation, the whole A/O biofilm system could achieve an everage COD removal efficiency of 22%, with the best of 50%.To improve the treatment efficiency, a microbiological method was reviewed by isolating and screening a specific strain of halotolerant bacteria. After a primary identification, the halotolerant bacteria screened out is a gram-negative bacteria, streptobacillus, with the shape feature of [(0.6~1)×(2~3)]μm. Under a condition of tenmperature 37℃, contact time 9h, organic load 10.39 kgCOD/(kgMLSS·d), the halotolerant bacteria could reach a high COD removal efficiency up to 65% through a static experiment. Besides, when the enriched halotolerant bacteria was applied into MBBR, the COD removal efficiency of the MBBR could be increased from 20% to 47.5%, which also proved that the halotolerant bacteria screened out has a high capability of specific degradation, and is a effective way in treating the landfill leachate with a high salinity, high toxicity and hardly biodegradable quality.