Excessive biomass accumulation and bio-activity loss in biofilter (BF) and biotrickling filter (BTF) can lead to unreliable long-term operation. In this study, UV photodegradation was developed as a strategy of controlling biomass accumulation to recover BF and BTF for the treatment of gaseous alpha-pinene (α-pinene) over long-term period. With the addition of UV, an overall efficiency of more than 85% was re-achieved in BTF since excessive biomass was removed. Due to continuous positive effects by UV photodegradation, biomass concentration in the BTF was kept at a normal level (9.25–9.58 kg m −3 dry carrier), and the maximum elimination capacity and CO 2 production increased by 4.2 and 6.2 times that achieved by the deteriorated BTF. Microbial analysis revealed that microbial community structure in BTF became more complicated with the addition of UV photodegradation. Kinetic analysis indicated that photodegradation could improve the removal process of α-pinene in BTF. Contrarily, UV photodegradation could not recover BF based on similar experiments. These findings provided a potential use of UV photodegradation for maintenance of biotrickling filtration efficient for gaseous pollutants removal over long-term operation.