Biodegradation of LAS in the anaerobic water of a representative inlet of Lake Dianchi

Biodegradation and degradation kinetics of anion-surfactant (LAS) in the anaerobic water of a representative inlet (Haihe River) of Lake Dianchi under different incubation conditions were studied by the 'river die-away' test method. The influences of temperature, pH, initial concentration of LAS, aeration condition and added nutrients (NH4Cl or NaH2PO4) on the biodegradation of LAS in the water were investigated. The results demonstrate that LAS can be biodegraded by microorganisms in the water and that the percentage of degradation of LAS was in ore than 95% after 26 d. The biodegradation of LAS fit the second kinetic model. Incubation temperature,. initial concentration of LAS, aeration and added nutrients (NH4Cl or NaH2PO4) can all affect the biodegradation of LAS. When the incubation temperature increased from 10 degrees C to 25 degrees C, the biodegradation rate (p) of LAS increased from 0.21 d(-1) to 0.90 d(-1). The LAS degradation rate increased from 0.72 d(-1) under anaerobic condition to 1.97 d(-1) under continuous aeration condition. The increased initial concentrations of LAS lead to decrease of the biodegradation rate. NaH2PO4 accelerated the degradation of LAS but added NH4Cl instead inhibited degradation. In our experiment, pH value (7.05-9.44) had little influence on the biodegradation of LAS