| The biological treatment is the mainstream technology for VOCs control with high efficiency, low consumption, mild reaction conditions and low secondary pollution. The excessive growth and non-uniformal distribution of biofilm lead to layer clogging and deterioration of operating performance. Therefore, in order to obtain a long-term efficiant and stable operation of the reaction system, it was necessary to control the biomass within reasonable limits, and to ensure its degradation activity. Setting five sets of bio-trickling reactor (A-BTF without ozonation, B,C,D,E-BTF with different micro-ozone) was developed to analyze the enhancing mechanism of micro-ozonation on BTF for VOCs treatment by controlling biofilm for avoiding the BTF failure over extended operation.The performance of the five sets of biological trickling filters differentiated during their running which was similar to each other in the early time. In the operation period (before150th day), the toluene removal efficiency of A-BTF was around90%. Then it’s removal performance of the A-BTF began to decline at150th day. It was obviously that in the same operation condition, B, C-BTF showed the toluene removal efficiency of B-BTF above85%and80%, respectively. The removal efficiency of D, E-BTF had remarkbly declined during the whole operation. The yields of CO2and toluene elimination capacity were linear related. The mineralization rate in A, B, C, D, E-BTF was around67.3%,76.3%,73.1%,60.8%and57.8%, respectively. It was showed that micro-ozene (≤10mg/m3and24h continuous control) wasn’t harmful to organism, and could be effectively and lengteh the operation cycle of BTF, which was the effective mean to control the performance deterioration caused by excess biomass gowth and non-uniform distribution during long operation.The biomass in A-BTF accumulated seriously. It was less serious and more evenly in B, C, D, E-BTF. The monitoring of relative hydrophobicity of biofilm surface and zeta potential which was closely related with accumulating ability between biofilm showed that micro-ozone could effectively slow down the increase of hydrophobicity and the decrease of electronegativity on biofilm surface. The secretion of total EPS, extracellular protein and PN/PS gradually increased up and polysaccharide secretion did not changed obviously in biotrickling filter. The change trend of the average molecular weight of EPS was the same as zeta potential. The result of FTIR and XPS further showed the main chemical components of EPS in the operation period. The analysis of Biolog showd that micro-ozone would not reduce the activity of microbe in BTF.According to PCR-DGGE fingerprinting analysis, the microbial species were very rich and had the relative stability and complexity of microbial community structure in five BTFs during the operation in52days,136days, and220days. Compared to A-BTF, the communities of B, C, D, E-BTF had been significant changed, indicating micro-ozone affected the communities evolution in BTFs. The clone library sequence analysis indicated that the microbial community structure of BTF was remarkably changed, under micro-ozone. High-throughput sequencing was used to further analysis of microbial community structure. Gammaproteobacteria was dominant srain in five BTF, which was widely distributed withinBTF. Actinobacteria and Flavobacteria were the sub-dominant strains in B, C-BTF, respectively. Compared to other BTFs, it indicating the Actinobacteria and Flavobacteria was key factor of degradation of toluene, but also indirectly it can tolerate a small amount of ozone (10mg/m3), and had a positive role to extend the running time of the reactor and running performance... |
PDF Full Text Request