CASE STUDY
Wastewater municipality saves $35 million with one-step nitrification/de-nitrification
The Problem
Trinity River Authority, TX (162MGD) needed an optimal nutrient removal strategy for a planned significant expansion in capacity. Assuming a standard two-step nitrification/de-nitrification process, the budgeted capital cost was $50 million.
The Solution
Under the guidance of Leon Downing, PhD, PE, a Consulting Engineer and Northwestern University, McCormick School of Engineering, a one-step nitrification/de-nitrification process was validated over five years by gradually reducing dissolved oxygen (DO) levels to a super low setpoint. Microbe Detectives next generation DNA analysis and other test methods were used to measure changes in the ecology and validate results.
Action: Gradually progressed from 2.0 mg/l to 0.2 mg/l dissolved oxygen (DO) operating conditions over 5 years in 4 aeration basins.
Result: Commamox (CMX) bacteria was validated to emerge and become the primary “workhorse” delivering an improvement in nutrient removal at a super low DO setpoint with a one-step nitrification/de-nitrification process.
Benefits
Basin Design Savings: $35 million
Pre-study $50 million estimated
Post-study $15 million actual cost
Operating Savings: $490,000/year
$350,000/year aeration savings
$140,000/year chlorine savings
