When the EPA 503 Regulations were first enacted the RDP EnVessel Pasteurization Process was the most popular Class A Process on the market due to it’s simplicity, cost effectiveness and the market demand for lime. RDP has over 70 operating systems in the USA making the EnVessel Pasteurization process one of the most popular Class A processes current in use.

The popularity was driven in part by the use of supplemental heat instead of overdosing with lime. We utilize a patented process utilizing supplemental electrical heat and lime addition. The sludge is heated in the ThermoBlender to meet the EPA 503 Regulations of 158 – f for 30 minutes. Lime is added to meet pH and vector attraction requirements, thereby meeting the basic requirements for Class A status. The low lime dosage reduces operating costs and produces a more balanced nutrient enhanced end product then a straight lime pasteurized product.

The Pasteurization vessel provides over 30 minutes of retention time. It is essentially a 48" wide belt conveyor that creeps along at 4 inches per minute. Over top of the belt, we have an insulated bay that is electrically heated.
Pasteurization vessel

The ThermoBlender is an electrically heated pug mill. The sludge cake temperature is elevated to 158°F. Lime is mixed in to achieve a pH of at least 12.0.

New Bern Solids Handling

An interview with the plant managers in New Bern, North Carolina