[Preparation of a Nutritional Slow-release Packing Material with Function Microorganisms and Its Characteristics Evaluation].

A nutritional slow-release packing material with function microorganisms (SC) was prepared using emulsification and the cross-linked method. Its potential as packing material in biotrickling filters (BTF) for butyl acetate removal was evaluated. The physicochemical properties show that the packing has a porosity of 92.6%, bulk density of 40.75 kg·m-3, surface area of 2.45 m2·g-1, and real density of 551.52 kg·m-3. The packing material contains hydrophilic groups (O-H, C O) on its surface and nutrient elements (N, P), which are distributed uniformly, with release rates of 22.35 and 8.36 mg·(L·d)-1, respectively. The biomass concentration of the packing (protein/packing) is 14.61 mg·g-1. After storage for 7 and 30 d, the microorganisms fixed on the packing material could still remove more than 96% of butyl acetate. The BTF using SC as packings reach stable performance within a short time (8 d) and the removal efficiency is maintained at 94% unless there nutrition is supplied or the pH is adjusted. The BTF with polyurethane as packing material need a longer time to start up and the removal efficiency decreases to 80% under the same operating conditions. High-throughput sequencing analysis shows that the fixed degrading stains are dominant during the whole operation and the microbial structure is more stable, which could sustain the stable removal of butyl acetate in BTF using SC.

An innovative nutritional slow-release packing material with functional microorganisms for biofiltration: Characterization and performance evaluation.

The type of packing material for biofiltration has a great impact on microbial growth and pollutant removal. This study evaluated the feasibility of a nutritional slow-release packing material with functional microorganisms (NSRP-FM) in a biofilter for the removal of gaseous n-butyl acetate. Through the emulsification-cross linked process and microbial immobilization, an innovative packing material was obtained, with a specific surface area of 2.45 m2 g-1 and a bulk density of 40.75 kg m-3. The cumulative release rates of total phosphorus and total nitrogen were 90.6% and 75.6%, respectively, as measured while continuously spraying deionized water. To evaluate the performance of biofiltration, NSRP-FM was compared with the commercial polyurethane foam (PU-foam), in two identical biotrickling filters (BTFs). The BTF packed with the prepared NSRP-FM maintained a consistent removal efficiency (over 95%) without nutrients addition and pH adjustment. The other BTF had poor removal performance, and the removal efficiency declined to 65% when there was no pH adjustment. Energy dispersive X-ray spectroscopy (EDS) analysis of NSRP-FM showed that inorganic elements were released during the operation of BTF. The abundance of functional microorganisms suggested that the prepared NSRP-FM provided a better environment for microbial growth, despite changes in the operating conditions.