Improvement of energy efficiency at the wastewater treatment plant in Freist
About This Opportunity
This is a works contract in the water and sanitation, energy and power and architecture and engineering sectors, with a focus on Structural Engineering, Energy Efficiency, Wastewater and Sanitation. Located in Germany, Europe, this opportunity is open to firms and consortiums. Proposals must be submitted before August 3, 2026.
Published through service.bund.de (Germany), a national government procurement portal. Public procurement tenders follow the country's national bidding regulations and may have specific eligibility and documentation requirements for civil works in the water and sanitation sector. Works contracts of this nature generally require demonstrated experience in similar infrastructure projects, adequate equipment and technical personnel, and financial capacity including bank guarantees. Interested parties should review the full documentation on the original source before submitting their proposal.
Description
Auto-translated from German, possibly divided into lots Type of service: Improvement of energy efficiency at the wastewater treatment plant in Freist by renewing the pressure aeration in both activated sludge tanks, switching to intermittent aeration, and optimizing the control of aeration and agitator operation. Scope of service: 1. Renewal of pressure aeration in the two activated sludge tanks, 2. Switch to intermittent aeration, 3. Optimization of aeration and agitator operation control Renewal of tank aeration The two combined tanks are equipped with approx. 192 linear meters of pipe diffusers, type Magnum 2000 from OTT, each. According to local information, the aeration system has not been renewed since commissioning. The more than 20-year-old aeration system will be converted to plate diffusers. The plate diffusers will be arranged in a sector with an occupancy area of ~ 40 ° across the width of the respective circular tank. The agitator locations will be retained. The existing 4 slow-running agitators will be replaced by VFD-controlled agitators P ~ 2.3 kW, d ~ 2.5 m. The required 27 or 21 diffuser plates per tank will be arranged in one sector. The air supply for the diffuser plates will be provided via the existing air supply from the tank's inner wall. The downpipes will be made of HDPE pipe material. A shut-off valve will be provided for each diffuser plate. This ensures the operational reliability of the permanently installed diffuser system. The agitator in each of the activated sludge tanks facing the aeration field will operate as a VFD-controlled continuous runner. The agitator facing away from the aeration field will be switched off during the aeration phases. The switching frequency will be limited. Conversion of aeration The registers with the shut-off valves for each diffuser plate are accessible from the outer wall of each tank. An injection point for optional formic acid dosing using a mobile dosing station will be installed on the supply air line of each tank and the riser pipe. The mobile dosing station is not part of this tender. The agitator in each of the activated sludge tanks facing the aeration field is to be operated as a VFD-controlled continuous runner. The agitator facing away from the aeration field will be switched off during the aeration phases. The switching frequency will be limited. The necessary changes to the control system of the aeration system for switching the operating mode must be carried out in the process control system. In normal operation, as before, two blowers will continue to be assigned to each activated sludge tank. The collecting lines must be adapted to the new blower configuration. To increase failure safety, a connection between the two blower groups will be created. The lines will be equipped with valves. Emergency operation will not be automated. Optimization of aeration control and regulation By continuously measuring the NH4 and NO3 concentrations in both activated sludge tanks in addition to oxygen and phosphorus content, the aeration can be adapted to the load-dependent demand based on the respective NH4 and NO3 concentration when integrated into the control system. The controllers, PD controllers, are read out via RTC software and can thus capture absolute concentrations as well as the rate of change. The control algorithm calculates a variable oxygen setpoint. The prerequisite for energy-efficient utilization of the generated air volumes. By defining the target values for the parameters NH4 and NO3, the cleaning goal is defined and specified as the first priority. The O2 controller, installed as a secondary element in the algorithm, controls the activated sludge tank assigned to it with a performance requirement of 0/20 - 100 %. Furthermore, the PO4-P concentration in the wastewater of each activated sludge tank is monitored to prevent excessive P-release during denitrification phases. In addition to stabilizing nitrogen removal performance, load-dependent aeration is expected to reduce aeration energy by 10% compared to the actual energy consumption of the biology. g) Information on the purpose of the building or contract, if planning services are also required Purpose of the building: Purpose of the contract: h) Division into lots (type and scope of lots see letter f) Award by lots: Yes Offers are possible: for one lot only: No for one or more lots: Yes for all lots only (all lots must be offered): No i) Execution deadlines Start of execution: 05.10.2026 Completion or duration of services: 17.12.2026 further deadlines: j) Ancillary offers only allowed in conjunction with a main offer k) Several main offers allowed l) Provision/request of tender documents Tender documents will be made available electronically at: https://www.evergabe.de/unterlagen/54321-Tender-19f1776161e-622
Data provenance
This notice is sourced from service.bund.de (Germany) and was originally published on July 13, 2026. Last refreshed 1 day ago. Original language: German. BidsFactory mirrors official procurement notices and links back to the source for full legal text.
About Abwasserzweckverband Wipper-Schlenze
Abwasserzweckverband Wipper-Schlenze has issued 8 procurement notices on BidsFactory, including 5 currently open and 0 awarded contracts. Activity concentrates in Water & Sanitation, Energy & Power, and Architecture & Engineering Services. All notices are published for Germany. Notices are distributed via service.bund.de (Germany). Most recent publication: July 28, 2026.
Frequently asked questions about this tender
How can I submit a bid?
Visit service.bund.de (Germany) to access the full notice, required documents, and submission instructions provided by the contracting authority.
When does this tender close?
The submission deadline is August 3, 2026. You have 5 days left to prepare and submit your proposal to the contracting authority.
Who is the contracting authority?
This notice was issued by Abwasserzweckverband Wipper-Schlenze in Germany. The authority is responsible for evaluating bids, awarding the contract, and managing performance.
What type of contract is this?
This is a Works contract in the Water & Sanitation sector. The classification helps bidders match the opportunity to their qualifications and registered scope of supply.
Where will the contract be performed?
The contract is for delivery in Germany. Foreign bidders should review local registration, taxation, and any in-country presence requirements before submitting.
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