Industrial Pretreatment and Combined Heat and Power Facilities Development

CHA and H&V Consulting designed and constructed a new 200,000 gpd industrial wastewater pretreatment facility to support existing production as well as the expansion of Monogram Foods’ production facilities in Martinsville, Virginia. The new pretreatment facility treats the process wastewater using an anaerobic contact process, and the biogas produced during treatment is used to produce both heat for the pretreatment facilities and power for the manufacturing plant operations. The plant is a model for both energy efficiency and sustainable waste treatment, and it includes the following elements:

• 1.5 million gallon mixed anaerobic digester with a flexible dome cover to biologically degrade waste loads and convert them to biogas. The digester will be followed by a dissolved air flotation unit (DAF) that will separate and return the anaerobic biomass to the digester, while liquids will pass through for subsequent treatment.
• 100,000 gallon aerobic moving bed biofilm reactor (MBBR) will further treat the liquid stream, bringing the plant effluent within discharge limits. A second DAF will again separate solids, returning some to the digester while discharge liquid is pumped to the receiving sewer.
• 50,000 gallon tank will store excess solids from the digester DAF. These solids will be hauled off by truck and land-applied as soil amendment.
• Energy recovery system consisting of a 400 kW packaged engine-generator that utilizes the produced biogas to generate electricity and heat for use within the Monogram facilities
• Containerized 1.5 MBTU/hr. natural gas boiler will be provided as a backup for digester heating
• Improvements to an existing wastewater equalization tank to accommodate the new process. The tank will be covered with a fixed fiberglass roof, and the existing aeration equipment in that tank will be replaced with pump mixing.
• Tankage and equipment to allow Monogram to feed solid food and captured grease into the treatment system. These waste streams are currently disposed of off-site. By running them through the digester, their weight and volume will be significantly reduced, and the digestion of these wastes will produce additional biogas and generate additional electricity and heat.

The treated wastewater is discharged to the local sanitary sewer in full compliance with local regulations and limits.