An evaluation of current and potential technology for the treatment of farm dairy effluent in New Zealand - Assessing the potential to use anaerobic digestion and sequencing batch reactor technology as an alternative method of treatment of farm dairy effluent
Buchanan, K. (2020). An evaluation of current and potential technology for the treatment of farm dairy effluent in New Zealand - Assessing the potential to use anaerobic digestion and sequencing batch reactor technology as an alternative method of treatment of farm dairy effluent (Thesis, Master of Environmental Sciences (MEnvSci)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/13544
Permanent Research Commons link: https://hdl.handle.net/10289/13544
In order to keep up with social and consumer demands the regulations surrounding nutrient losses from dairy farms in New Zealand are becoming harsher. A way in which dairy farms can reduce the loss of nutrients is to improve the management of farm dairy effluent (FDE). FDE management can be improved by adding a treatment. This treatment may be chemical or biological. The objective of this research was to develop a method of biological removal of nutrients from farm dairy effluent that enables more efficient management of those nutrients. The system that resulted (BioClean) was a five-stage system including; solids separation, anaerobic digestion, an enhanced biological nutrient removal sequencing batch reactor, sand filtration and UV disinfection. Modelling of the BioClean system and current methods of FDE handling and treatment, found that BioClean outperformed all current technologies (two pond treatment, land application and ClearTech) in the removal of nitrogen from the liquid fraction (average removal of 98%). The removal of phosphorus and potassium from the liquid fraction were not found to be sufficient for discharge to waterways with average residuals of 13 mg/L and 772 mg/L (Table 32) respectively. Removal of Escherichia coli by BioClean was found to be vary significantly with scenario variation (from a mean of 0 cfu/100ml to 16,260 cfu/100ml). Analysis of the model found that variation in results could potentially be explained by the model simulation. Therefore, even though scenario and treatment variation were found to be statistically significant (p<0.05) in most cases, the cause of that variation can not confidently be linked to either the treatment change or variable that changed with regards to scenario differences. Economic analysis of the addition of the BioClean system to a New Zealand dairy farm found that if the desired levels of nutrient removal could be achieved the addition of the BioClean system to a dairy farm was to be viable. The system was found to reduce daily running costs in comparison to the typical land application system due to pumping only the liquid fraction of FDE after solid separation a short distance. Future research into the BioClean method through a lab-scale trial was recommended to improve the accuracy of the model and optimise the operating system.
The University of Waikato
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- Masters Degree Theses