Acid whey is a by-product of the quarg production and arises in large volumes in dairies. A considerable disposal problem arises due to the lack of obtainable proceeds from acid whey utilisation. Additionally, sustainable and energy efficient treatment methods for high strength liquid wastes from dairies cleaning operation are needed to reduce the costs of wastewater treatment. Samples of acid whey and spent cleaning solutions from a quarg cheese production plant were collected. The composition and physical properties were analysed and evaluated against waste treatment process requirements. The occurrence of different waste streams, their volumes and frequencies were also investigated. A laboratory scale membrane nanofiltration plant was designed, and built for investigation of the volume reduction of cleaning process effluents with emphasis to treatment options for the filtration concentrates. The examination of the rheological properties of alkaline CIP wastewaters at different volume reduction ratios clearly shows that these effluents are Newtonian fluids even at high concentrations. The anaerobic biodegradability of acid whey and mixtures containing portions of alkaline CIP wastewaters at different volume reduction ratios was tested. Characteristic process kinetics for acid whey fermentation in batch mode was observed. The occurrence of a second lag-phase in mixtures containing larger portions of acid whey was identified as phase separation- due to rapid acidification of lactose. Anaerobic digestion (AD) was identified as a suitable treatment option for acid whey and alkaline CIP wastewaters. Four anaerobic digester types were designed with regard to their suitability for high strength waste treatment and were built and operated at laboratory scale. The reactors tested were: a) A Continuous Stirred Tank Reactor (CSTR); b) An Anaerobic Membrane Reactor (AMR); c) An Upflow Anaerobic Sludge Blanket (UASB) re- actor; and d) A novel two-stage process design consisting of a combined acidification and crystallization stage and a gaslift driven fluidised bed methanogenic stage. The operation of the AMR process and also of the UASB process with internal circulation and pH-control using alkaline CIP effluents was evaluated at high loading rates of 7.7 g•L-1•d-1 and 10.2 g•L-1•d-1 respective. However, in the experiments it was demonstrated that even with perfect biomass retention the operation of one stage anaerobic digestion at high loading rates caused process upsets. Precipitation and accumulation of milk minerals within the sludge was observed in all one stage experiments. The conclusions drawn from one stage studies led to the design of a novel high-rate diges- tion system to meet the demands of anaerobic digestion of acid whey and effluents from dairy plant cleaning. The design based on different high-rate industrial reactor designs and incorporate the ideas of staging, crystallisation of calcium salts prior to anaerobic di- gestion, fluidised bed and internal circulation reactors, and also jet-loop or gaslift reactors. The performance of the novel system when treating acid whey is comparable to the results of well designed, two-stage digesters treating cheese whey which is easier to digest.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:551134 |
| Date | January 2011 |
| Creators | Mohr, Jan-Christian |
| Publisher | University of South Wales |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://pure.southwales.ac.uk/en/studentthesis/optimized-utilization-of-quarg-production-residuals(6a7a4f48-5aa2-40b4-a100-ad7daa8d1a59).html |
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