BIOSTYR® BAF vs. Conventional Activated Sludge

Carbon Footprint
Technology Comparison

Analysis

Several options were studied for the upgrade of this WWTP, including Conventional Activated Sludge (CAS) and Biological Aerated Filter (BAF).

The BAF option was selected for plant upgrade, with John Meunier Inc. as the supplier of the BIOSTYR® units. The main benefit of this selection was the small physical footprint requirement of the BIOSTYR® as well as its lower CAPEX and OPEX compared to other technologies.

Technology Design Data

The installed BIOSTYR® secondary treatment receives primary treated effluent. Average daily flow is 95,000 m3/d with a peak flowrate of 192,400 m3/d. Influent sewage characteristics are: BOD of 64 mg/L,TSS of 78 mg/L, TKN of 15 mg/L, TP of 1.7 mg/L. Required treated effluent characteristics are: BOD below 15 mg/L, TSS below 15 mg/L, Ammonia in the 5-12 mg/L range depending on season.

Eleven BIOSTYR® cells were installed, each of 147 m2 surface area. One backwash tank of 847 m2 was also installed. The BIOSTYR® has a total installed surface area of 1,617 m2 with a depth of 3.5 m of floating media with 3.6 mm of diameter. Three duty and one standby aeration blowers each with 150 HP motors were installed.

The CAS compared option was based on two aeration tanks with a total area of 5,000 m2 at 5 m of water depth and four clarifiers with total area of 5,278 m2 at 5 m of water depth.

Evaluation Boundaries

For the evaluation of the BIOSTYR®, the items taken into account were the concrete poured for the 11 cells, the structural steel used for the reinforced concrete, the steel used for all ancillaries (sluice gates, blowers, piping, etc.), the polystyrene used for the floating media and the electricity costs over a 20 year evaluation.

As for the Conventional Activated Sludge (CAS), the concrete and structural steel for its re-enforcement in the aeration tank as well as in the clarifiers were taken into account. A similar weight of ancillaries (sluice gates, piping, blowers, etc.) were evaluated. Electricity costs were taken into account for a 20 year evaluation.

Carbon Footprint per Cubic Meter of Water Treated*

 

Carbon Footprint over Life Expectancy of the System*

 

Conclusions

This case study has demonstrated that the BIOSTYR® technology not only meets the stringent design criteria, but offers a solution, in these conditions, that is 19% less intensive in terms of carbon footprint than a Conventional Activated Sludge (CAS) operating in the same conditions for 20 years.

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