310 CMR 32.80 - Appendix A: Acceptable Processes for Pathogen Reduction

Acceptable processes which will significantly reduce pathogens are:

(1) Aerobic Digestion: A process during which sludge or septage is broken down by bacteria by agitating the sludge or septage, mixing it with air or oxygen, and maintaining residence times ranging from 60 days at 15°C to 40 days at 20°C, with a volatile solids reduction of at least 38%.

(2) Air Drying: A process in which sludge or septage is allowed to drain and/or dry on under-drained sand beds, or paved or unpaved basins in either of which the sludge or septage is at a maximum depth of nine inches. This process is acceptable only if it occurs for at least three months during which temperatures must average, on a daily basis, above 0°C for two months.

(3) Anaerobic Digestion: A process during which sludge or septage is broken down by bacteria in the absence of oxygen at residence times ranging from 60 days at 20°C to 15 days at 35°C through 55°C, with a volatile solids reduction of at least 38%.

(4) Low Temperature Composting: A composting process using the within-vessel, static aerated pile, or windrow methods. For all three methods, the composting temperature shall be not less than 40°C for five consecutive days, and not less than 55°C during four hours of this five day period.

(5) Lime Stabilization: A process in which lime is added to sludge or septage to produce a pH of 12 after two hours of contact with the sludge or septage.

(6) Other methods: Other methods or operating conditions may be deemed acceptable by the Department if the owner or operator can provide data showing that the pathogen and vector attraction of the volatile solids are reduced to an extent equivalent to the reductions achieved by any of the other methods listed above in 310 CMR 32.80. Written approval of equivalency by the Department shall be required.

Notes

310 CMR 32.80