Assessment of Options for Anaerobic Digestate Management
Anaerobic digestion is becoming an increasingly popular method for processing organic residuals. Anaerobic digestion generally consists of pretreatment to appropriately size, mix and homogenize the residuals streams, contaminant removal, and digestion in a single-stage, multi-stage or batch process that is further defined by operation under mesophilic or thermophilic temperature regimes. The two primary by-products of anaerobic digestion are biogas and digestate. Belkorp Environmental Services Inc. (Belkorp), which manages and transports municipal solid waste generated in Metro Vancouver to the Cache Creek Landfill, is investigating opportunities to construct and operate anaerobic digestion facilities to manage source separated residential / commercial food waste. The goal of anaerobic digestion would be to produce compressed natural gas to fuel Belkorp’s fleet of waste management vehicles. One consideration in the evaluation of anaerobic digestion opportunities is the management of the digestate generated through this process.
Belkorp retained SYLVIS to conduct an assessment of management options for digestate. The assessment included a literature review of current practices and related environmental considerations. SYLVIS also conducted a review of regulations and guidelines in British Columbia covering digestate management. Representative digestate data were used to determine land base requirements for beneficial use. SYLVIS provided Belkorp with scenarios for digestate transportation and management, including the use of digestate to establish coppice willow plantations. An economic analysis provided an estimate of capital and operating costs associated with digestate management and beneficial land application system.
SYLVIS provided Belkorp with critical information on the regulatory, logistical, environmental and financial aspects of the management aspects of digestate from food waste anaerobic digestion. This information will support Belkorp’s decisions in sizing and locating future anaerobic digestion facilities, to ensure they operate with maximum efficiency and provide the greatest environmental benefit through offsetting fossil fuel use and maximizing digestate utilization.