Study On Treatment Of Wastewater From Livestock And Poultry By Coupling Process Of ABR And MABR

Livestock wastewater, which was characterized by high concentration of organic matter and ammonia nitrogen, will cause a series of ecological environmental pollution without treatment. This study employed a single anaerobic baffled reactor (ABR) and a combination of ABR and membrane biofilm bioreactor (MABR) to treat livestock wastewater. Start-up procedure, removal efficiency of pollutant and the operation characteristic were explored. The feasibility and optimization of these reactors were determined too. The results are as follows:The synthetic livestock wastewater was used as inflow treated by ABR which has been seeded with anaerobic granular sludge in advance. The pollution load gradually improved during ABR start-up. The start-up time lasted 64 days and the final removal efficiencies of CODCr and NH4--N were 98% and 19.27%, respectively. ABR keep on running well and stable removal rate of CODCr and NH4+-N (>80% and 15% respectively) under the condition of CODCr of 5000 mg/L, NH4+-N of 500 mg/L in inflow. Key parameters during ABR start-up:seeded anaerobic granular sludge with d50 of 0.89mm and MLSS between 30 g/L and 40g/L; the sludge occupied 1/3 volume of ABR; the initial CODCr is 2000mg/L, improving 30% each time as the reactor operated stably.During ABR start-up, the median diameter of granular sludge increased from 0.89mm to 1.18-1.58mm. The average growth rate was 7.28×10-3mm/d Structure of mature granular sludge was looser than seed sludge. Mature granular sludge in ABR showed hydrogel structure characteristic. Under conditions of neutral or acidity pH, the granules exhibited stronger elasticity and strength, which can also affected by ionic strength and temperature. The equilibrium water content (EWC) of mature granular sludge decreased with ionic strength enhanced or pH decreased and it showed tended to release water. PCR-DGGE results showed that first compartment had most abundant bacteria, including acid formation bacteria. Uncultured Clostridiales bacterium, Clostridium botulinum, Uncultured Acidobacteria bacterium, and methagens, Uncultured Firmicutes bacterium and so on.ABR-MABR was seeded with anaerobic granular sludge in advance, then improving pollution load gradually during its start-up. The start-up time lasted 49 days. The ABR-MABR demonstrated good CODCr removal performance with the removal sufficiency higher than 89%. The ABR-MABR also showed better NH4+-N removal performance than ABR did. The average removal rate of NH4+-N was 78.08% during steady state. Moreover, improving aeration quantity properly, increasing number of compartment or controlling the temperature to be 32±1℃ were conducive to nitrogen removing.Through scanning electron microscope (SEM) and PCR-DGGE analysis, the mature granular sludge in ABR-MABR composed of bacillus, filamentous fungus and a handful of sphaerophorus. The number of anaerobic bacteria was predominant in ABR-MABR. Meanwhile, nitrobacteria like Uncultured Nitrospira sp and obligate aerobic bacteria like Uncultured Arthrobacter sp were observed. Overall, the amount and species of microorganism in ABR-MABR were preceded than that in ABR.