Dover & Sherborn, MA Wastewater Treatment Plant

Dover & Sherborn, MA Wastewater Treatment Plant

Ground Water Protection: School WWTP Removes Total Nitrogen

Twenty miles west of Boston the rural towns of Dover and Sherborn, Massachusetts share a regional middle and high school facility. Both towns rely entirely on individual septic systems for their wastewater infrastructure. When the school decided to expand in 1999 the Massachusetts Department of Environmental Protection (MADEP) required that the school district install a wastewater treatment facility to comply with the state’s Groundwater Discharge (GWD) pollution control regulations. Under this guideline, any facility generating greater than 10,000 gallons per day (gpd) without access to an existing municipal sewer system must treat its wastewater to remove total nitrogen.

School waste streams can represent challenging conditions for biological treatment processes. Given school sanitary routines, the potential for toxic shock loading and peak hydraulic loading is high. Furthermore, ammonia nitrogen concentrations in the influent are typically 4-5 times that of typical domestic wastewater. The schools engineer selected an AquaPoint BioclereOH treatment system for its proven nitrification  and denitrification performance capability, energy efficiency and low life cycle costs. The plant is designed for a maximum daily flow rate of 15,260 gpd.

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Design Characteristics

Influent Effluent
 DESIGN FLOW (GPD)  15,260 15,260
BOD5 (mg/l) 500 < 30
TSS (mg/l) 350 < 30
TKN (mg/l) 160
AMMONIA‐N (mg/l) 130 < 3
NITRATE‐N (mg/l) < 5
TOTAL‐N (mg/l) < 10

Performance Data

2014 BOD5 (mg/l) TSS (mg/l) Nh3 (mg/l) TN (mg/l)
APR  9 6.5 0.1 4.65
MAY 6 2 0.1 9.65
JUN 18 5.7 2.7 4.7
JUL 2 2 0.1 3.5
AUG 12 5.7 0.1 6.55
SEP 6 5.7 0.6 6.6
OCT 20 2.8 2.3 3.05
NOV 6 11 0.67 3.2
DEC 3 2.5 0.1 4.05

System Diagram