N.H. Admin. Code § Env-Wq 713.03

Current through Register No. 50, December 12, 2024

Section Env-Wq 713.03 - Activated Sludge: Aeration System Performance Requirements

(a) To allow for increased energy efficiency in WWTF operation through the expected life of a WWTF, the owner shall:

(1) Provide multiple blowers for diffused air systems that are sized to:

a.Meet the current facility peak aeration demand;

b.Meet turndown requirements as described in (b), below; and

c.Avoid over-aerating at current daily minimum flows;

(2) Conduct an energy evaluation to determine the optimum blower sizing, turndown, and staging;

(3) If current peak aeration demands are below peak design aeration demands, provide sufficient blower capacity to meet current peak aeration demands while ensuring that blower rooms are large enough to accommodate the blower configuration necessary to meet peak design demands;

(4) Demonstrate financial capacity or set up a reserve account to set aside the estimated money required to install additional blowers when needed to meet increased peak aeration demands; and

(5) Arrange blowers in such configuration and capacities as to meet the current peak aeration demands with the single largest unit out of service.

(b) The aeration system shall be designed to:

(1) Have sufficient turndown capability that does not extend beyond the efficient operational range of the blowers, when using multiple same-sized blowers or staging with multiple varied-sized blowers;

(2) Not over-aerate or require blowing off excess air at initial year minimum flows; and

(3) Operate most efficiently at average organic loading conditions.

(c) Air requirements for a diffused air system shall be determined incorporating the following factors to be included in the design specifications or supporting documentation submitted to the department:

(1) Tank depth;

(2) Alpha factor of waste;

(3) Beta factor of waste;

(4) Certified aeration device transfer efficiency;

(5) Minimum aeration tank dissolved oxygen concentration;

(6) Mixing requirements needed to maintain solids suspension;

(7) Critical wastewater temperature; and

(8) Altitude of WWTP.

(d) Aeration requirements for carbonaceous BOD₅ removal shall be based upon the maximum monthly BOD₅ loading.

(e) All aeration equipment shall be capable of maintaining a minimum of 1.0 mg/L of dissolved oxygen in the mixed liquor unless a lower minimum dissolved oxygen can be justified based on process modeling.

(f) Diffused air system design shall use data derived from pilot testing or an empirical approach.

(g) When pilot facility or experimental data is not available, the design oxygen requirements shall:

(1) Be 0.8 to 1.2 pounds of oxygen per pound BOD₅ removed;

(2) Be 4.57 pounds oxygen per pound design maximum day total Kjeldahl nitrogen (TKN) available for nitrification, where TKN available for nitrification is calculated as influent TKN less nitrogen required for carbonaceous growth less non-biodegradable nitrogen; and

(3) Include oxygen demands due to high BOD₅ and TKN concentrations in recycle flows such as heat treatment and digester supernatants, vacuum filtrate, belt filter pressate, waste sludge recycled to primary clarifiers, and elutriates.

(h) The aeration system shall be designed to match the diurnal organic load variation while economizing on power input.

(i) The capacity of the blowers or air compressors shall be based on the site altitude and site specific minimum and maximum summer and winter temperatures.

N.H. Admin. Code § Env-Wq 713.03

(See Revision Note at chapter heading for Env-Wq 700) #8590, eff 3-25-06

Amended byVolume XXXIV Number 46, Filed November 13, 2014, Proposed by #10693, Effective 10/15/2014, Expires10/15/2024.