This case study from the Waste Water Treatment Plant in Munich, Germany shows how it gained a capacity increase with the same footprint by replacement of valves and diffuser plus increase of water level.
The need to remove more nutrients and so improve cleaning performance required a capacity increase. Since the footprint was limited, further measures must be taken in the nitrification tanks (B-step): increase of water level, replacement of the diffuser elements and separate treatment tanks for digestate. These actions increase the dynamic pressure and so power consumption of the blowers. But blowers must be also able to handle these higher pressure requirements. The butterfly valves were replaced by a totally new on the market und unique in design aeration control valves with especially low pressure loss.
Customer Benefits
→ Annual energy savings
→ Demand-based air supply with a wider control range
→ more stable DO-concentration because of high precision control ability
→ no need to replace the blowers – jet control valve compensated completely the higher pressure demand
→ side stream treatment runs with flexcontrol – system
Challenges
The increased dynamic counter pressure must be compensated by the valve to prevent a need for new blowers.
The old ceramic diffuser was replaced by new membrane diffuser with 20% higher SOTE with 20-30 mbar higher pressure loss.
20 cm increase of water level increase static counter pressure roughly for another 20 mbar.
Binder had developed a completely new aeration control valve, but not yet tested in any real plant.
The orientation of the upstream butterfly valve was causing a lot of turbulences downstream – a CFD-simulation was necessary to estimate the effect on the flow reading. Finally the position 0.5*D in front of the control valve was fixed as the best installation position.
CFD was used too to check, how uniform the flow is in the outlet of the valve and to decide, if the first dropper pipe(s) can be kept as they are or if they must be dismantled and re-fitted more downstream again.
Sidestream treatment was built on another place to reduce the nitrogen load from nitrification tanks, equipped with a full VACOMASS® system.
Solution
Process & Control improvement:
The butterfly valves were replaced by VACOMASS® jet control valve, valve with a nearly linear operational characteristic and a very low pressure loss in control mode. The valve position control became an easy task, since the valve has a linear operation characteristic in a very wide range.
The AI-supported algorithm of the installed aeration controller for side stream treatment calculates dynamically in real-time the air flow requirements for each of the 3 zones and the related required stroke of the valves. The system was integrated into the existing SCADA infra-structure with minimal effort and in a short time.
Reduction of power consumption:
The VACOMASS® jet control valves have an extra-ordinary Venturi design and so related very low pressure drop of the valve (significantly lower compared to all available common valves on the market). It could more than compensate all increased counter pressures, at the end header pressure could be lowered too.
Results after replacement of diffuser
The new diffuser were more efficient than the ceramic old ones. They get 20% more oxygen into the tanks with same air flow rate as before – no additional power consumption.
In the first years after start-up every year one valve gets investigated for ay wear – no wear could be detected and so there was no need for maintenance.
Typical system response to a load changes (side stream)
– automatic adjustment of DO-SET concentration, based on actual ammonia load Monitoring of all zones and automatic improvement of load distribution to the 3 aerated zones, calculation of valve opening, and system pressure to stabilize treatment performance
Next step: install the aeration controller in the nitirification step of the plant
OPEX Savings
Plant data
- Average air flow rate 8+2 tanks: 68,000 Nm³/hr
- Specific costs electricity: 0.30 EUR/kWhr
- Average efficiency of the blowers: 0.7
- CO2-Emissionfactor: 0.363 kg CO2/kWhr
Based on a pressure balance it becomes clear, that the jet control saves min. 40 mbar compared to the butterfly valve and same number in case of other aeration control valves in the aeration tanks. 40 mbar → 280,000 EUR per year
Based on CFD-simulation it comes clear, the first dropper pipes don´t need to readjusted and fixed
→150,000 EUR as a single case
Since there is no dynamic header pressure system installed in the aeration tanks, also sidestream aeration
can run only with constant header pressure. Energy savings are already included above in the 66,000 Nm³/hr.
Improvement CO2-footprint: 108 kW → – 343 t CO2/year
Further positive side effects:
- no need for new blowers
- precise aeration control
- One step ahead with digitalization and automatic operation
CAPEX
800,000 EUR including installation & costs for pipe adaptations & implementation in the SCADA
In Summary
INDUSTRY: Municipal wastewater treatment
CAPACITY: 290,000 m³/d, 2,000,000 PE (120 g COD/ PE/day)
TIMEFRAME: 2014 – 2022
SYSTEMS / PRODUCTS: 38x VACOMASS® jet control valves, flow meter in the main stream, 6x VACOMASS® jet control valve, flow meter and flexcontrol in the side stream
TREATMENT PROCESS: Activated sludge with upstream, Denitrification in a AB-plant
TECHNICAL HIGHLIGHTS: I-based DO-control, dynamic header pressure control via MOV/MIV, DO-SET NH4-N, side stream treatment
CUSTOMER INVESTMENT: 450,000 € (including installation and pipeline adjustments)
For more information contact: Australia — Tony Girach Em Email: tony.g@pumpandvalve.com | Phone: 0419257719 New Zealand — Justin Engels Email: justin.e@pumpandvalve.com | Phone: 09 276 9045
