Abstract
This work represents and reviews a compilation of investigations into improving anaerobic digestion performance of high-strength wastewater in the Australian Red Meat Processing industry. The industry produces significant quantities of organic-rich wastewater which requires treatment prior to release to the environment. Anaerobic lagoons are a cost-effective method of waste treatment where land availability is not an issue; however, the high fat load in the wastewater can negatively impact the anaerobic lagoon system and result in compromised anaerobic digestion performance. This paper will discuss the importance of upstream primary pre-treatment and review a series of investigations focused on optimising digester performance and improving fat biodegradability. These studies include: 1. the effect of temperature and mixing; 2. the influence of feedstock trace element composition and supplementation, and; 3. the potential benefit from pre-treatments such as chemical, thermobaric, thermochemical and bio-surfactant. This paper discusses the implications of these findings for covered anaerobic lagoon operation and provides recommendations to promote optimum digester performance and future opportunities in adopting alternate anaerobic digestion technology options. Finally, the paper provides recent trends toward the use of other waste streams for co-digestion and discusses this in terms of digester optimization and technology options.
Highlights
The Australian red meat processing (RMP) industry is both energy and resource intensive
Six reactors were operated at 38 °C and half were reduced to 25 °C over a Following temperature reduction, the organic loading rate was progressively increased in a step-wise period of 90 days
While optimum conditions typically associated with high-rate systems demonstrably improve digester performance, these conditions can be difficult to achieve in RMP facilities
Summary
The Australian red meat processing (RMP) industry is both energy and resource intensive. From the 7.7 million cattle processed in 2019 [2], this equates to an industry-wide production of 2.2 Mt of carcass weight [3] and a subsequent consumption of 20.68 million m3 of fresh water and 9038 TJ of energy [1]. The average rate of wastewater production was 8.7 m3 ·t HSCW−1 for an industry total of 19.14 million m3 in 2019 [2,4] This wastewater is high-strength with both a high chemical oxygen demand (COD) and a high fat, oil and grease (FOG). The eco-efficiency manual for meat processing [13] identifies several of these technologies, their costs and indicative capacities for fat recovery. Recommendations are made to inform future decision making regarding anaerobic lagoons for treating high-fat RMP waste
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