Smart Water Filters for Pesticide Removal

Background

Pesticides used to treat crops enter water courses via surface water run-offs. These can persist in water bodies for long periods and they have a significant impact on water quality and the environment. The legal framework that needs to be fulfilled is set by the EU Water Framework Directive, which limits their single concentrations to 0.1 micrograms per litre and 0.5 micrograms per litre for the sum of all pesticides. Removing Plant Protection Products (PPPs) from water masses is challenging, costly and energy-intensive. Moreover, some are UNTREATABLE and require additional treatments to ameliorate their impact and the problems they cause to the water treatment plants. Also, there is the added problem of historical contamination. Some will not simply disappear if they are banned, as they will be in sediments and ground waters for years. So, there is still an urgent need to find a solution for the cost effective removal of pesticides from potable water. An example of a pesticide that presents a problem, likely to remain with us for a while, is metaldehyde. Metaldehyde will be banned from 2022. It is presently widely applied to wheat and oilseed rape to treat slugs. Water companies estimated that the cost to build a plant just to deal with this one would be £600 million with an annual operating cost of £17M. This is just an example of how expensive pesticide water treatment can be. Other PPPs pose a more long lasting problem as they are also untreatable and there are no alternative products for growers to use.

Technology Overview

For the last 10 years, the University of Lincoln’s researchers have developed expertise on the production of materials to aid in the selective trapping of compounds. The Universities team has already developed smart materials based on polymeric compounds that effectively detect and trap other dangerous substances, such as explosives, organophosphate insecticides and heavy metals. As an example, the researchers have just recently finished a project, funded by the University of Cambridge, for the elimination of pesticides in water masses that constitutes the backbone of this proposal for the IN‑PART Global Challenge. Also, the same basic technology was very much behind one of the case studies submitted by the University of Lincoln to the recent Government’s evaluation of research (REF2021). The main researcher’s case was given scores with elements of world class and internationally excellent research. Moreover, one of the examples of the university’s purification and trapping technology (purification of vanadium electrolytes) has been selected as finalist for this year’s RSC Emerging Technologies competition (July 2022). The University of Lincoln’s group can produce these selective smart materials, using computational calculations and they can tailor synthetic routes to produce them, so they are highly specific to the target compound. Based on this technology, the researchers have created a proof-of-concept- smart water filter (TRL 4) capable of selectively trapping five of the most common UK’s pesticides and a plant growth regulator. These are: Aminopyralid, isoxaflutole, metaldehyde, quinmerac and chlormequat. A single smart filter can incorporate a mix of the selective materials, allowing effective removal of several pesticides using a single cartridge or the researchers can produce specific filters for each target. This filter is a unique and sustainable solution to trap PPPs at volume with the advantage they are recyclable and can be reused after appropriate cleaning and disposal of the PPPs. An important factor is the fact this technology is compatible and complements present water treatments as they can be added to existing water purification lines. To date, no existing on-site technology used in the purification of water can specifically target a specific compound that may be a problem.

Stage of Development

Technology is at TRL4, with demonstrators for each of the pesticides produced. The University’s production process allows for an easy scale up, and the University has industrial partners that can fulfil that role. Work done includes: (a) the design and production; (b) characterisation of the materials using Raman/Infrared spectroscopy and Scanning Electron Microscopy; (c) sorption/desorption capabilities, using liquid chromatography/mass spectrometry to track the pesticides in the water and extraction liquids. Work needed to be done includes: (1) further study of number of cycles the material can withstand binding/desorbing processes; (2) tests in real environments; (3) an accurate estimation of capacity of trapping per mass unit; (4) a degradation study to assess environmental and toxicological impact (Though the researchers have used bio-compatible materials).

Benefits

• Ability to target selected compounds
• Complementing present water treatment methodology
• Easy to fit/unfit without causing major disruption to existing water treatments
• Economic given its reusable nature

Applications

To date, the group has designed several materials but the major applications have involved the production of filter materials for water treatments dedicated to:

• Pesticides removal
• Heavy metal removal (without the need of flocculation)
• Organophosphorus compounds

the potential to adapt the materials to other target compounds is very high.

Opportunity

The University’s aim is to find a partner that can implement the technology in real environment and could help commercialising. A partner with the capacity to scale up would be very interesting, although the researchers have access to industries that could do the job, if necessary. Licensing the technology is the University’s preferred option. In this scenario, the researchers can design and produce proof-of-concept materials, developing sufficient amounts to develop a comprehensive study of viability before proceeding to scaling up and commercialisation.