Respirometry

1. Respirometry Optimizing aeration by tracking bacterial activity in Activated Sludge The Strathtox and Bioscope from Strathkelvin Instruments Ltd

2. The process as we all know it

3. CO2 + H2O Respiration CHO + O2 Growth Bacteria New biomass What the process is doing Organic load ends up as CO2 or new biomass Respiration is integral to BOD removal

4. Respirometry • Measures the bacteria’s rate of oxygen up-take • Tells us their REAL oxygen needs • Shows us how there activity is effected by different influents • Real sludge, real time

5. Applications of Respirometry • Biomass viability or ‘sludge health’ • Short and long term monitoring e.g. look for chronic inhibition • Toxicity management • Calculates inhibition rates and identifies EC 50 • Rapid influent screening • Check tankered waste for toxicity and avoid high re-agent costs since they use plant bacteria • Process Optimisation • Determine operational problems using bacterial OUR analysis. Make informed decisions to resolves sludge blanket and odour problems.

6. Applications of Respirometry • Aeration requirement and efficiency • Critical Oxygen point analysis saves a UK water company 40% of their energy costs • Nutrient management • Pulp and Paper mill reduces urea dosing costs by 70% • Nitrification status and capacity • A WWTP is able check how influents will effect their nitrification and so protect their compliance and avoid fines • Short-term BOD • Check operational changes now rather than in 5 days so avoiding consent issues

7. Applications of Respirometry • Aeration requirement and efficiency • Critical Oxygen point analysis saves a UK water company 40% of their energy costs

8. Aeration Efficiency Establishing what the bacteria need and optimising accordingly can….. • Reduce aeration costs • Solve process issues (odour, rising sludge, foaming…) • Increase treatment capacity • Balance flows

9. Energy Efficiency • The wastewater industry is constantly faced with increasing costs that stem from aging infrastructure, new health regulations and population growth. • Energy efficiency is a viable solution to these challenges.

10. Energy Efficiency Typically aeration accounts for 30 - 70% of the total energy consumption in an aerobic biological treatment plant Reducing these aeration requirements by 10 - 40% could result in savings of between $282k and $1M a year on a WWTP of 100 MGD.

13. Critical concentration Respiration rate 9 0 Oxygen Concentration (O2 ppm) Aeration Efficiency

14. Poor aeration efficiency Treatment effected Ideal operating area Respiration rate Oxygen transfer efficiency 9 0 Oxygen Concentration (O2 ppm) Aeration Efficiency

16. 1.88

17. 1.17

18. Rate of Respiration is not a fixed value • When the bacteria are feeding • When the BOD is depleted (Starving or ‘endogenous’ rate) • When inhibitory conditions are present in the mixed liquor • Seasonal (temp)

20. Bioscope

21. Bioscope • Profile biodegradation rate (OUR) • Real time conditions • Energy and treatment optimization with critical oxygen point • Measure temp, DO, SVI and SSVI

22. Biodegradation, DO, Settlement Profiling.

23. Profiling a site

24. Site profile

27. NOUR profile

28. NOUR & DO profile

29. Optimization Use it to prove and control existing proposals (e.g. scheduled retro fits) or to identify new opportunities Risk management • Multi-stage process controlled and monitored • Auditable