Immobilized microbial degradation technology has the advantages of simple solid-liquid separation, strong toxicity resistance, and low sludge yield. This study creatively added biochar to the immobilized microbial activated pellets and optimized the immobilization conditions for these pellets. This experiment also studied the removal efficiency of chemical oxygen demand (COD), total phosphorus (TP), ammonia nitrogen (NH3-N) and total nitrogen (TN) for immobilized microbial pellets in the SBR (Sequencing Batch Reactor) with different dosages and hydraulic retention time (HRT). Results showed that the optimal conditions were reached when: the mass fraction of SA (sodium alginate) was 2%, the amount of PVA (polyvinyl alcohol) was 4%, and cross-linking time 24 h, the best biochar added was RS700. Mixed bacteria under the condition of the optimization system for immobilized pellets were added to the continuously running of SBR process, 20 mL bacteria suspension of immobilized pellets could be used to test the best dosage through the experiment monitoring. In a comprehensive consideration, the optimal HRT was 4 d, and the removal efficiency of COD, TP, NH3-N and TN under the best dosage was reached at 76.79%, 56.50%, 67.60 % and 54.92% at 4 days, respectively. In the SBR process, the degradation efficiency of immobilized pellets for each pollutant COD, TP, NH3-N and TN in the SBR conforms to the first-order kinetic model.
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