Pioneering Real-time Observations with BioElectrochemical Systems

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The PRO-BES project (Pioneering Real-time Observations with BioElectrochemical Systems) will undertake simultaneous field trials of real-time water quality biosensors in wastewater treatment works spread across the UK. The project progresses an innovative collaboration between Newcastle University and University of South Wales, and is supported by end-users Welsh Water, Northumbrian Water and Chivas Brothers.

Building upon prior BBSRC funding, a laboratory proof-of-concept biosensor will be fully realised as a pre-commercial device ready for deployment and scaled-up manufacture. The biosensors incorporate tubular Bioelectrochemical Systems in which wastewater is flowed through a chamber containing a carbon anode on which a microbial biofilm is grown from wastewater. The electrogenic biofilm is capable of generating a voltage by oxidation of organic matter coupled to the reduction of oxygen to water at a platinised cathode (separated by an ion exchange membrane). The electricity generated is correlated with the Biochemical Oxygen Matter (BOM; or related organic load parameters e.g. BOD5, COD, TOC), whereas the presence of toxic compounds can be simultaneously detected by inhibition of the biofilm activity.

The biosensor consists of a sensing array of BES (to maximise dynamic range) and further includes online pH, conductivity, temperature sondes. The BES sensor demonstration system can be controlled to test under different flow rates, temperatures, and angle of orientation (venting of gases vs sludge accumulation). This maximises the research benefit by combining the controlled nature of experimental design with the variability of a real-world wastewater feed. An understanding will be gained of how biofilm microbial communities respond to key operational factors (temperature, flow rate, external resistance) and how changes in biofilm dynamics/activity affect response of the sensor, giving valuable insights for future research, development and optimisation.

The BES biosensor in the PRO-BES project will enable companies dealing with wastewater to modernise their existing water quality monitoring systems. The project will achieve impact by advancing development of a laboratory novelty towards a system that has been field tested for real-world application, taking the sensor to TRL 8+ as a prerequisite for commercial investment. Replicate biosensors will be tested in multiple locations across the UK by Newcastle University and University of South Wales providing valuable data regarding biofilm development in diverse wastewater environments.

Organic load monitoring is not only a benefit to Water companies treating municipal wastewater but also Food processing (Livestock, Seafood, Dairy, Bakery, Meat, Potato, Oil), Drinks processing (Soft drink, Brewery, Distillery), Oilfield and Refinery, Detergent, Pesticide, Textile, Rubber, Paper and Pharmaceutical industries.

Currently >1% of Europe's electrical consumption is used for wastewater treatment, of which aeration represents 55.6% of water company's usage. Water companies can therefore receive multiple benefits from real-time, online monitoring as they presently continuously aerate due to lack of process information. Monitoring incoming wastewater influents enables generation of a high-resolution historical record (c.f. monthly spot samples), and with this data treatment processes can be controlled and optimised. This brings about operational efficiencies so that treatment regimes can be tailored to loads and therefore cost savings (from lower aeration costs) and faster, pro-active reactions to incidents are enabled. Alarms and thresholds can be set to alert responsible parties to respond to pollution events immediately. This reduces the productivity burden of sending personnel to sites to perform checks end-users have informed us about, and allows workforces to be directed based on treatment demands. Trade effluents from smaller industries (such as those mentioned above) which feed into municipal treatment plants can be monitored for consent prior to exposure to the biological treatment systems. Monitoring discharged effluents can track treatment efficacy (and feedback to process control), indicate compliance with regulatory standards and therefore enable companies to avoid costly fines for consent breaches (£27m in 2016/17).

This also therefore brings about environmental benefit to the receiving water bodies which treated waters are discharged into. Pollution incidents can be identified in real-time without relying upon regulator monitoring or waiting for significant negative environmental consequences to arise, preventing severe environmental damage and with concomitant benefits to the public. Regulatory bodies such as the Environment Agency in the UK (and equivalent organisations in other international countries) could install sensors at strategic points within river systems to enable pollution source tracking and improve enforcement. This would allow these regulatory agencies to be more efficient in their work, and would provide the benefit of improving receiving water quality. As this is a concern of the EU Water Framework Directive which sets standards for receiving water quality, EU member states employing online sensors could therefore avoid sanctions for non-compliance owing to their more rapid and accurate response to emerging threats to water quality. In the long-term, real-time, online monitoring could lead to evidence-based policy change and become a requirement either in addition or superseding existing monthly offline spot sampling routines.

There is further societal impact for all users of water downstream of facilities or locations where online monitors are installed. Water can be used confidently in the knowledge that pollution incidents can be identified before harmful pollutants can accumulate. Water quality will improve due to the more frequent and accessible monitoring of the standard of water.