Ammonia Recovery and Hydrogen Generation

by Patrick McClead, Organics Group

Located in the central region of the UK, the Midlands Living Lab, hosted by Severn Trent Water (STW), in collaboration with Coventry University, Organics Group, and Environmental Monitoring Solutions (EMS), has three streams of activity;

  • Leakage detection module – implementing live trials of fibre as a means of leakage; a no-dig leakage repair technique; smart meters trials and analysing the best use of smart meter data; a smart valve solution (valve optimisation & automation); and proving an AI-based leakage robot.
  • Smart wastewater management – demonstrating the power of IWANs in addressing hydraulic capacity issues in wastewater networks.
  • Ammonia recovery and hydrogen generation – ammonia scrubbing and electrolyser demonstrators; processing centrate WW to recover ammonia and generate ‘green’ hydrogen.

STW has committed to research, explore, and develop opportunities for ammonia extraction and hydrogen generation to enhance environmental and financial performance.  A recovery process would avoid circa 3.7KtCO2 of process emissions from our conventional biological treatment processes, generating an ammonia product that could either eliminate the release of 15KtCO2 associated with the production of ammonia or be converted to 400t of hydrogen to displace three million litres of diesel road vehicle fuel.  STW is collaborating with Coventry University and Organics to deliver this project.

Coventry University has been developing a lab-scale electrolyser designed to convert recovered ammonia to hydrogen.  

 To date, various electrolyser cells have been designed, built and trialled with the aim of finalising the most effective cells for the pilot electrolyser. 

Design for electroyser, Coventry University

Organics Thermal Ammonia Recovery (OTAR) Technology

Organics has been providing thermal ammonia removal technology as a nonbiological application, for over two decades to sites in Hong Kong. These sites have some of Asia’s most challenging contaminated wastewater issues and are very restricted on land availability, with undulating topography, and highly populated areas. A combination of 14 landfill and one AD site in Hong Kong presently use the technology, some have been operating for 20 years, and there are two new sites coming online.

Figure 1: Organics Thermal Ammonia Removal Plant – Hong Kong

The REWAISE OTAR builds upon advances in energy efficiency measures developed over the twenty years, making the thermal process more efficient and sustainable, using appropriately scaled and sequenced economisers and heat exchangers.  OTAR can operate using various energy formats such as biogas, natural gas, exhaust heat, and low-grade waste heat from jacket waters.

The OTAR plant differs from the Hong Kong plant as, alongside the standard stripping and scrubbing columns, it includes a rectifier column, for ammonia concentration.

The OTAR operating philosophy is based upon a ‘switch on and monitor approach’ using the skill sets of operatives/technicians familiar with standard electrical and mechanical plant.  Therefore, the plant requires very little intervention post start up, other than the recording of data for trials and the occasional visual inspection of the plant.

Figure 2: OTAR Process

Organics is also supporting Coventry University with the design and build of a prototype, pilot-scale, electrolyser that will generate hydrogen from the recovered ammonia. 

The recovered ammonia solution will be used as a source of hydrogen to be produced using the electrolyser. The ammonia solution will also be investigated as a source of carbon free fertilizer.

The design and build of the ammonia recovery system has been completed and the OTAR Pilot plant is presently being shipped to the REWAISE Atlantic Hub located at STWs Resource Recovery Innovation Centre (R2IC) at Spernal, to assess its performance and the efficacy of the recovered ammonia and generated hydrogen.

Figure 3: OTAR Pilot Plant



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