Development Of Biotrickling Filter For Biooxidation Coal Mine Methane And Synthesis Polyhydroxybutyrate

The present study aimed at maximizing the performance of a standard biotrickling filter(BTF) devoted to the treatment of CH4 at low concentrations. Methanotrophs are a physiological group of bacteria with the ability to utilize CH4 as a sole carbon and energy source. This feature can be used to development of cost-effective and environmentally friendly CH4 abatement technologies, biotrickling filtration being one of the most cost-effective configurations due to its robustness and low operating costs. Methanotrophs with high biocatalic activity was enrich from coal mine soil with methane as the sole carbon source after domestication for long time. The medium nutrient components and culture conditions are optimized in order to achieve quick propagation of methanotrophs. Biofilters are filled with packing materials, factors affect methanotrophs grow on the packing material of the biofilter as biofilm are researched. Several packing materials have been studied for the capacity to allow for the establishment of biofilms of methanotrophs. The key operating parameters for the biofiltration performance, such as moisture content, nutrient content, empty bed residence time(EBRT), and CH4 concentration are studied. The methane absorbed by the methanotrophs in the liquid and biofilm can be bioconvert to polyhydroxybutyrate(PHB) as intracellular carbon storage. The PHB content in the drainage medium was studied. The main results from studies are achieved as following:Methanotrophs with high biocatalic activity was enrich from coal mine soil with methane as the sole carbon source after domestication for long time. This strain was identified as gram negative bacteria and belong to methylomonas according to 16 s RNA sequence.This strain can use one carbon compounds(methane and methanol) as carbon source for growth, can also use multiple carbon compounds, such as pyruvic acid, citric acid, Glucose and sucrose et al. for growth. Using NO3-1 as the nitrogen nutrition methanotrophs growth better than NH4+. The optimize media component for methanotrophs growth was Na NO3 10 m M/L, PO4-3 10 m M/L, Cu2+ 30 M/L and Fe2+ 60 M/L. Adding non-aqueous 5%(v/v) silicon oil in the medium can significantly promote methanotrophs catabolic activity.Ceramic pall ring surface more rough than plastic hollow ball, so it’s more favorite methanotrophs growth on the surface to form more and stable biofilm. Increasing inoculation numbers with methanotrophic cultures can accelerate biofilm maturation on the packing material. The time of biofilter successful startup reduced from 22 d to 18 d.When the biotrickling filter was operated at a liquid recycling velocity of 0.1L/min and inlet methane concentration of 1.1% and inlet gas flow rate of 2L/min and Na NO3 of 70 m M/L, the elimination capacity reached 39.72 g/h/m3. The elimination capacity decreased when using(NH4)2SO4 and NH4NO3 as nitrogen source in the drainage medium. The concentration of PO43- in the drainage medium increased from 10 m M/L to 100 m M/L, the elimination capacity increased from 39.72 g/h/m3 to 46.81g/h/m3.The biotrickling filter operated at the same conditions, with inlet gas flow rate increased from 2L/min to 3L/min, the elimination capacity ascend from 41.84 g/h/m3 to 49.6g/h/m3, the pressure drop increased significantly from 82 Pa to 115 Pa.The best PHB extract parameter was that the methanotrophs cell suspended in chloroform/sodium hypochlorite(1:1) mixture, and then incubated 1h at 60 ℃. The extracts were subjected to methanolysis in the presence of methanol and sulfuric acid 3%(v/v). The reaction mixture was incubated at100℃ for 4 hours.Using methane as carbon source for methanotrophs growth, add 1% citric acid and pyruvate in the medium can promote PHB biosynthesis, yield of PHB were 139μg/ml and 150μg/ml respectivly.The PHB in the drainage NMS medium of biotrickling filter operation 1 week accumulated 2mg/ml at drainage of 0.1L/min and inlet methane concentration of 0.7% and inlet gas flow rate 2L/min. The drainage medium amount increased to 0.2L/min, the PHB production increased to 2.6 mg/ml.