Effect of biofilm thickness and carrier type on the performance of anaerobic moving bed biofilm reactors (AnMBBRs)

Detta är en Master-uppsats från Lunds universitet/Kemiteknik (CI)

Sammanfattning: The anaerobic moving bed biofilm reactor (AnMBBR) is a wastewater treatment process that has shown effective for the treatment of industrial wastewaters. As the AnMBBR is a biofilm process, nutrients, products, etc. must be transported through the biofilm. The thickness of the biofilm may, therefore, impact the process. The objectives of this study were (1) to evaluate the effect of the biofilm thickness and carrier type on the performance (in terms of soluble organic removal, “sCOD removal”, and biogas production) of AnMBBRs and (2) to assess the effect of the different carriers on biofilm development and accumulation. Three continuous lab-scale AnMBBRs were operated, fed with industrial wastewater from food processing. The reactors were filled with two different carrier types (commercial AnoxKTM Z-200 carriers and a prototype of AnoxKTM Z-1000 carriers) allowing for different maximal biofilm thickness (200 μm and 1000 μm respectively). The results from this study suggested that the biofilm thickness and type of carrier influence the performance of AnMBBRs. The reactor filled with Z-200 carriers showed a low performance with a fluctuating sCOD removal not exceeding 73% and a methane content in the biogas of 63 ± 2%. The results from the reactors with Z-200 carriers were comparable to other studies made on AnMBBRs treating industrial wastewaters from food processing. They had high sCOD removal efficiencies of over 90% and methane content in the biogas of 69 ± 2% and 68 ± 2%. The study also showed that the rate of biofilm accumulation was considerably higher for the Z-1000 carriers, as compared to the Z-200 carriers, possibly as a result of the biofilm being less exposed to hydraulic shear in the deeper Z-1000 carriers. Even though there was more biofilm in the reactors with Z-1000 carriers, the specific removal rate was higher in the reactor with the Z-200 carrier. This suggests that the biofilm on the Z-200 carriers was more active or specialized compared to the biofilm on the Z-200 carriers.

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