Impact case study database

The accumulation of mussels and clams in waterways has become a key issue for water companies in the UK; the blockage that accumulation of zebra mussels can cause in waterways is shown in Figure 1, an image of a raw water pipe, half-filled with the animals. The adoption of BioBullets by UK water companies has changed how this industry approaches the control of existing zebra and quagga mussel infestations, leading to a reduction in the use of chlorine in water supplies and so reducing a major human and animal aquatic toxin. Further, , BioBullets are being used as the first approach to addressing new challenges as the mussels spread and invade previously unaffected systems. .

Figure 1. Blockage of a raw water pipe in southern England showing an accumulation of zebra mussels that have half-blocked the pipe.

Guidance and approvals

In 2018, based on underpinning University of Cambridge research, BioBullets created two revised formulations that showed substantial improvements over previous products:

1. the new products have a longer dissolution time (3 hours compared with 1-2 hours), enabling use in longer pipelines;

2. one of the products has elevated toxicity to mussels, requiring lower doses (5 mg/l compared with 25 mg/l) and shorter dosing times (3 days compared with 10 days) resulting in a 16x reduction in product application;

3. the particles are significantly smaller (7-25 μm) than previous formulations (101-105 μm) [R4] and more closely mimic natural food particles in size, enabling a much more targeted and efficient delivery to mussels, which prefer particles of 10-20 μm.

Product improvement was achieved by three key production innovations: (i) faster peripheral velocity using a rotary atomiser; (ii) refined machining, surface finish and profiling of the atomisation disc imparted more energy into the liquid film; (iii) improved rheological properties of the premix slurry created a lower viscosity premix [R6].

The two new formulations (Silver Bullets 1000 and Silver Bullets 2000) were approved by the UK Drinking Water Inspectorate in the same year under Regulation 31 of the Water Supply (Water Quality) Regulations [E1, page 18]; within this regulation, the BioBullet is the only mussel control solution that has been approved for use. At the same time, the products were assigned a new category, moving from Section A.4, which only allowed use while the waterworks is off-line, into Section A.9, which allows for use while the waterworks is online under standard operational conditions. This new listing dramatically enhances the commercial viability of the products as they can be used without having to temporarily stop the waterworks from supplying drinking water during treatment. As such, this new approval enables mussel control with minimal impact on standard operational procedures.

Impact on water supply companies

To date, BioBullets products have been used by seven UK water companies (Anglian Water, Bristol Water, Northern Ireland Water, Severn Trent Water, South Staffs Water, Thames Water, Welsh Water) which collectively supply 52% of the UK population (34.7 million people) with drinking water. [Text removed for publication], serving a population of 1.1 million people and all the associated businesses in an area of 2,400 square kilometres around [text removed for publication], has estimated BioBullets to be 69% cheaper than the pre-chlorination approach they previously used, saving them GBP188,000 per year [E2].

Bristol Waters' first trial of BioBullets took place in early September 2019 at Purton Treatment Works in Gloucestershire, which supplies over 400,000 people in the City of Bristol and surrounding areas. A survey undertaken at the canal abstraction point six weeks after dosing recorded a mussel mortality rate of 44% despite the trial taking place outside the optimum seasonal window. Encouraged by these results Bristol Water ran a further trial in October 2020, and data indicate that mussel mortality will exceed the desired target of 60%.

In addition to the commercial product itself, Bristol Water’s Quality Scientist and Sampling Technician Manager states that they have “received sound technical guidance from Dr David Aldridge at every stage and site support was provided prior to the trial to ensure correct application of the product and to confirm an appropriate, repeatable method for accurately quantifying mussel mortality.” [E3]

Thames Water is the UK’s largest water and wastewater services provider, supplying 2.6 billion litres of water a day to 15 million people within a 13,000 square km area, from parts of Gloucestershire in the west, to areas of Kent and Essex in the east (Thames Water, About Us). They outline that mussels growing in stored water tunnels present a double risk to the water supply by blocking flow and requiring tunnels to be taken out of service for cleaning, at a cost of around GBP1M per annum. Their lead research scientist says, “Following a review of possible control methods BioBullets were selected as the most attractive solution for mussels in our 96km of vulnerable tunnels. [They have] demonstrated that mussels can be controlled in stored water tunnels and pipes in a way that does not add risk to the water quality or downstream treatment process.” They describe it as an affordable solution that has the benefit of being deployed as a portable treatment plant for a limited number of weeks, in contrast to longer term storage of hazardous chemicals. The SB2000 product helped them clear an operationally critical supply pipe, which had become blocked with zebra and quagga mussels [E4].

[text removed for publication] provides water and sewerage in [text removed for publication]; daily, they supply 560 million litres of clean water for almost 1.8 million people and treat 320 million litres of wastewater ([text removed for publication] About Us). In their report on the use of BioBullets from July 2020, they state that dosing with BioBullets removed [text removed for publication]

Impacts on commerce

The formation of BioBullets has led to employment within Biobullets Ltd [text removed for publication] [E6], pages 56 and 59. There have also been commercial benefits for the product manufacturer, TasteTech Ltd, as follows. Since 2014, TasteTech Ltd, has successfully increased their annual turnover from GBP4.9M to GBP7.1M and increased their staff from 55 to 67. The Managing Director of the company says that their collaboration with BioBullets “has helped the company develop and grow in several ways”. These include: increasing their knowledge of microencapsulation particle construction, which has helped them improve products for the food industry; purchase of new equipment that would otherwise have not been acquired, and which has “proved invaluable” enabling them to predict and optimise performance; and development of their internal strategy to establish new alliances with several large companies and institutions [E7].

Research at the University of Cambridge, which generated the product of BioBullets, has enabled a novel approach to tackle a significant issue for the UK water supply industry, offering a cost-effective solution that avoids use of chlorine, a compound that can be harmful to animals and humans. As a commercial entity, BioBullets now provides employment and is a profitable company contributing to the UK economy.