Case Study: Green Schools Cost Savings

Green Schools Cost Savings

MAINTENANCE CASE STUDY

CLIENT

Upper Grand District
Central Algoma School Boards

LOCATION

Erin Ontario
Brisbane, Ontario
Sault Ste. Marie, Ontario

YEAR

2010

WATERLOO SYSTEM

TREATMENT CAPACITY

40,000 L/day
13,000 L/day
100,000 L/day

PROJECT SAVINGS

$60,000 per year in operating costs

APPLICATION

Schools

PROJECT TYPE

The Problem

In 2009 the Ontario Ministries of Research & Innovation and Education released a joint program called the Green Schools Pilot Initiative which aimed to reduce the environmental footprint of Ontario schools infrastructure by demonstrating and testing green technologies. After a multi-phase selection process Waterloo Biofilter Systems was asked to demonstrate high-level sewage treatment, nutrient removal, and wastewater reuse at three schools while significantly reducing operating costs compared to their existing wastewater systems.

The Upper Grand District and Central Algoma School Boards participated in the program because they had existing wastewater treatment systems that were either failing, underperforming, or proved too costly to operate. All three schools involved had historical effluent and maintenance costs available, and energy meters were installed on the existing systems prior to decommissioning to allow for directly comparable data to be collected.

Problem Continued...

Erin District High School Multi-Use Facility

This facility includes a 600-student high school as well as cafeteria, several offices and an ice hockey arena. It was serviced by a 160,000 L/day extended aeration package sewage plant installed in 2000, including denitrification tank with methanol addition, and a back-washable sand filter prior to subsurface disposal.  Effluent quality of the system had been good, however the school board found that operating the plant was very expensive.  There were also numerous complaints with nuisance odours and noise emanating from the aeration plant.

Brisbane Elementary School

This 416-student public school was serviced by a 14,000 L/day suspended-growth extended-aeration package plant installed in 2003.  Final effluent quality of the plant was very poor and had been consistently out of compliance regarding TSS, cBOD5 and nitrogen subspecies limits.

Central Algoma Secondary School

This 834-student high school with cafeteria was serviced by a 1970-era activated sludge-extended aeration plant designed for 132,000 L/day.  After chlorination, the effluent was discharged directly to Walker Creek which in turn outlets to Lake Huron. Several physical plant deficiencies and health and safety issues were identified by the plant operator.

Waterloo Solution

Erin District High School Multi-Use Facility

The aeration plus sand filter plant was replaced with a 40,000 L/day Waterloo Biofilter, WaterNOx™ B.A.F. for enhanced nitrogen removal, UV disinfection system, and 20-foot operator’s room all housed within three modified SC-40 shipping containers.  Effluent quality of the Waterloo Biofilter system meets the objectives while substantially reducing electrical and maintenance costs by 84% and 70% respectively – for cost savings of over $38,700 per year to the school board.

The Waterloo Biofilter substantially reduced noise pollution levels, with decibel readings reaching background levels of 40 dB after only 8 m distance from the plant. The school board has  not received an odour complaint since the aeration system was replaced.

Final effluent quality produced by the Waterloo Biofilter system is suitable for wastewater reuse for purposes such as toilet flushing and irrigation.

Erin cBOD5’ mg/L TSS mg/L TAN mg/L TKN mg/L Nitrate-N mg/L E. coli cfu/100mL
Objectives 10 10 2-3 3-4 3.6
Aeration Plant + Sand Filter
N=118
2 3 0.1 1.0 4.2
Waterloo Biofilter
N=144
4 3 0.1 1.0 3.0 <2
Distance from sewage plant (m) Aeration Plant (dB) Waterloo Biofilter (dB)
<1 91 55
3 79 43
8 69 40
15 63
30 55

Brisbane Elementary School

The aeration plant was replaced with a 13,000 L/day Waterloo Biofilter, WaterNOx™ B.A.F. for enhanced nitrogen removal, and UV disinfection system all housed within a modified SC-40 shipping container.  Effluent quality dramatically improved with the Waterloo Biofilter system in place.  Electrical and maintenance costs were reduced by 78% and 46% respectively – saving the school $5,400 annually in operating costs.

Final effluent quality produced by the Waterloo Biofilter system is suitable for wastewater reuse for purposes such as toilet flushing and irrigation.

Brisbane cBOD5’ mg/L TSS mg/L TAN mg/L TKN mg/L Nitrate-N mg/L E. coli cfu/100mL
Objectives 10 10 2 4 4
Aeration Plant
N=23
18 38 20.0 32.4 6.8
Waterloo Biofilter
N=81
5 8 0.4 1.6 4.6 <2

Central Algoma Secondary School

The aeration plant was replaced with a 100,000 L/day Waterloo Biofilter system with 20-foot operator’s room housed in three SC-40 shipping containers.  Electrical and maintenance costs were reduced by 65% and 60% respectively – saving the school $15,600 annually in operating costs.

Final effluent quality produced by the Waterloo Biofilter system is suitable for wastewater reuse for purposes such as toilet flushing and irrigation.

CASS cBOD5’ mg/L TSS mg/L TAN mg/L E. coli cfu/100mL
Objectives 10 10
Aeration Plant
N=31
3 19
Waterloo Biofilter
N=14
2 2 0.15 1050

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