Investigation on the difference between biofilm morphologies of the vermifilter and conventional biofilter with the flow cytometer.
With the demand of new sludge reduction processes, a vermifilter (VF) was studied based on a conventional biofilter (BF). The biofilm morphology was investigated using a new technique, the flow cytometer (FCM), to find a way to optimize VF structure. VF was inoculated with Eisenia fetida, packed with ceramsites, and operated stably at the organic load of 1.2kg-VSSm(-3)d(-1) with BF as the control. Compared with BF, VF had about 13% more removal efficiency of excess sludge and 45% shorter biofilm update period. FCM profile showed the morphology of microbial cells in VF biofilms was significantly different from that in BF in upper layers, with decreases of average refractive index (about 72%) and size (about 22%), and suggested it was better to keep earthworms there to remove rod-shaped microorganisms with other filter media in lower layers to remove spherical ones combining the findings in SEM images and extracellular polymeric substances.
Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Wanyin
W
Di
Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: xingmeiyan@tongji.edu.cn.
Meiyan
M
Xing
Institute of Biofilm Technology, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Jian
J
Yang
D000818:Animals; D018441:Biofilms; D005374:Filtration / Q000379:methods*; D005434:Flow Cytometry; D009835:Oligochaeta; D012722:Sewage / Q000737:chemistry / Q000382:microbiology
D012722:Sewage
Biofilm; EPS; Earthworms; Refractive index; Update period