Section Env-Wq 716.13 - Mechanical Sludge Dewatering(a) Mechanical devices acceptable to dewater sludge shall include belt filter press, centrifuge, rotary press, pressure filter press, and screw press.(b) The proposed use of less common alternatives, such as geotubes and rolloff containers fitted with screens, shall require supporting documentation demonstrating successful use in facilities similar to the proposed installation under similar design criteria and conditions.(c) Subject to (d), below, prior to selecting mechanical dewatering equipment, pilot testing shall be used to establish design criteria.(d) For facilities in which sludge is not available or is likely to change considerably in nature, successful performance from multiple facilities handling similar sludges under similar conditions and design criteria shall be documented and used to develop appropriate design criteria.(e) Mechanical dewatering units shall be capable of handling the maximum weekly sludge production in 30 hours, unless the equipment is designed for continuous operation.(f) If any period of unmanned operation is anticipated as a normal operating condition, then appropriate instrumentation and fail safe monitoring and alarms shall be provided.(g) Alarm systems shall be provided to notify the operator(s) of conditions that could result in process equipment failure or damage, threaten operator safety, or a sludge spill or overflow condition.(h) Belt presses and conveyors shall be provided with emergency pull cords along the entire length of the press that will:(1) Stop the press in an emergency; and(2) Trigger an audible alarm.(i) Chemical feed systems for sludge conditioning shall meet the requirements of Env-Wq 716.12.(j) A hose station shall be provided to allow for cleanup and wash-down of the dewatering area and equipment at the end of dewatering operations.(k) Ventilation of the dewatering area shall be in accordance with the NFPA as incorporated by reference in the state fire code in Saf-C 6000, to minimize the buildup of combustible gasses, odors, and humidity.(l) Where duplicate sludge dewatering units are not provided, a contingency plan shall be submitted with the basis of design, and sludge storage facilities shall be provided that are adequate to store sludge for the period of time anticipated for repairs to be made if the dewatering device is taken out of service for repair.(m) Sludge storage shall precede all mechanical dewatering units and shall be provided by the use of holding tanks or thickeners or chemical blending tanks, as required for the total dewatering process operation.(n) Dewatering sidestreams shall be returned to the treatment process as far upstream as practicable prior to the biological treatment unit.(o) A means shall be provided for measuring the quantity of sludge processed in both wet tons and dry tons.(p) Dewatering process rooms shall be lighted, heated, and ventilated, using energy efficient fixtures and equipment. Floors of process rooms shall be pitched 1/4 inch per foot to drain points and be slip proof.(q) Sludge dewatering process equipment shall be housed in processing rooms isolated from other portions of the WWTP.(r) Electrical systems and equipment shall comply with the NEC requirements adopted by reference in the state building code pursuant to RSA 155-A:1, IV, for the installed location.N.H. Code Admin. R. Env-Wq 716.13
Adopted byVolume XXXIV Number 46, Filed November 13, 2014, Proposed by #10693, Effective 10/15/2014, Expires10/15/2024.