Effect of nutritional bio-stimulants (NBS) on the biological treatment of the wastewater from traditional Chinese medicine production

Abstract

Nutritional bio-stimulant (NBS) technology is an attractive method to improve the efficiency of biological treatment of wastewater by stimulating the microbial growth and increasing species diversity. In this study, a commercial NBS, which consisted of organic acids, absorbable nitrogen and phosphorus and trace elements, was applied as a nutrient supplement to replace conventional chemical fertilizer (CCF) in aerobic biological treatment of a traditional Chinese medicine (TCM) wastewater. A mill trials was carried out in a commercial scale TCM wastewater treatment system for 41 days. The process performance and active sludge characteristics were continuously monitored when the CCF was replaced with NBS gradually in the system. It was found that the chemical oxygen demand (COD) of the effluent decreased from 118 to 89 mg·L^-1, well below the 100 mg·L^-1 wastewater discharge limit, when the CCF was replaced with NBS completely. More importantly, the ammonia concentration of the effluent stayed constantly low in the NBS stage of the trial, indicating that the added NBS was completely utilized by the microorganisms. In contrast, the effluent ammonia concentration was gradually increasing and exceeded the limit in the CCF stage of the trial, indicating that the CCF was not fully utilized by the microbes. The improved perfromance of the aerobic wastewater treatment system was attributed to the fact that the NBS nutrients were more bio-available than the CCF to the microorganisms.