| 1. |
- Björnsson, Lovisa, et al.
(författare)
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Effects of support material on the pattern of volatile fatty acid accumulation at overload in anaerobic digestion of semi-solid waste
- 1997
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 47, s. 640-644
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic degradation of a semi-solid waste with a total solids content of 4% particulate matter, much of it insoluble, was investigated in four laboratory-scale reactors. Two of the reactors were equipped with different textile materials for immobilisation of microorganisms, while the other two were used as continuously-stirred-tank reactor references, A constant organic loading rate and hydraulic retention time were used in the start-up period; the hydraulic retention time was then decreased and the effects of this change were monitored. Volatile fatty acid (VFA) concentration and pH were chosen as indicators of the microbial status in the reactors. The reactors with support material showed a greater resistance to overload than did the continuously-stirred-tank reactors. This is in agreement with many studies undertaken on the anaerobic treatment of wastewater. However, no problems with clogging occurred, showing that a support material is also applicable in systems treating waste containing large amounts of insoluble, particulate matter. The pH was comparable to VFA for indicating an approaching process failure. However, the pattern of VFA accumulation was qualitatively different between the reactors with and without support material, Obviously the metabolic pattern of mixed cultures changes when the microorganisms are immobilised.
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| 2. |
- Björnsson, Lovisa, et al.
(författare)
-
Supports made from recycled glass as biofilm carriers in anaerobic packed bed treatment of high-strength wastewaters
- 1997
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Ingår i: Resource and Environmental Biotechnology. - 1358-2283. ; 1, s. 243-256
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of using carriers made of recycled glass in anaerobic packed bed reactors has been studied in laboratory-scale experiments. Two types of carrier were studied: a porous bead of glass foam and an open ring of a smoother, sintered glass. The performance of processes with these carriers was compared with a conventional upflow anaerobic sludge blanket (UASB) process. The treatment of wastewater from a pulp and paper mill, and from a pharmaceutical plant was studied. Both carrier types were found to be suitable for supporting biofilm growth. With the porous beads, however, suspended sludge accumulated between the carriers, which caused clogging of the process. This, together with the low mechanical strength of the material, makes this carrier less suitable for full-scale processes. The sintered rings showed no signs of clogging and had better mechanical qualities and the maximum loading rate for pulp and paper processing wastewater was 10 kg COD m-3 d-1. This is similar to processes with commercially available plastic carriers, but with the UASB process, the maximum load with this wastewater was around 20 kg COD m-3 d-1, which makes the sintered ring process non-competitive. An anaerobic packed bed process with glass carriers could, however, find applications where the UASB process is not applicable. For example, the wastewater from the pharmaceutical plant could not be treated with conventional suspended sludge methods due to the toxicity of the effluent. Instead, treatment in a packed bed with porous glass beads was tested with good results.
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