Impact case study database

4.1 Design and introduction of novel technologies for the measurement of suspended solids in liquids and its commercial uptake – Process Instruments

Process Instruments (PI) Ltd are a SME who specialise in the measurement and control of water disinfection (potable and swimming pools), and the measurement and control of particle removal from potable and wastewater through coagulation and flocculation methodology. The desire to manufacture their own particle sensors, instead of relying on other commercially available devices from third-party suppliers Stemmed from the fact that, prior to the KTP programme with Lancaster University, there was no single sensor on the market that could span the range of 2NTU to 8% particle concentration; two separate sensors were required to achieve the same effect.

Optimisation of the chemistry of the coagulation and flocculation processes by Lancaster University [3.5] within the KTP programme, led by Fielden, resulted in the successful development of a particle sensor that could monitor the range of 2 NTU to 8% particle concentration, with significantly superior stability, linearity and dynamic range compared with any current commercially available particle sensor for deployment in both potable and waste waters. This enabled PI to launch two new products: SoliSense® [5.1] and Turbsense® [5.2]. Turbsense® is a further variant of the SoliSense® device, which has given Process Instruments a sensor design that covers extremely low concentrations of particles in water (0 to 10NTU). The sensor designs are very similar but adjusted for very low particle concentrations and combined with a specialised water sampling device (developed internally by Process Instruments as a follow-on to the KTP project) to eliminate the errors associated with micro-bubbles.

SoliSense has the greatest dynamic range of any commercial particle sensor and is a unique selling point, since third-party end users only need to purchase a single sensor, which reduces both initial cost and halves maintenance costs thereafter. Furthermore, the linearity of the sensor developed through [G2] has enabled the subsequent development of a novel patented algorithm [5.3] that fully compensates for drift, which is a significant problem with conventional suspended solids sensors. Since their launch in 2018, both SoliSense® and Turbsense® are manufactured by PI at their Burnley factory, and have sold over 660 sensors with sales exceeding GBP620,000 to end users in 24 countries [5.4].

4.2 Improved awareness and understanding of waste generation in paint manufacture resulting in changes in practice and process at Crown Paints

The partnership between Lancaster University researchers and Crown Paints was initially motivated by the company’s ambition to reduce the waste it generated as part of the paint manufacturing process, with the goal of becoming a net-zero waste paint manufacturer [5.5i-ii]. New water metering systems were installed at critical points in the manufacturing plant to gain the first accurate inventory of clean water usage and wastewater generation. This inventory enabled a clearer understanding of the origins and volumes of the paint waste streams, and the frequency of their generation throughout a production cycle and over the calendar year. The findings showed that Crown generated around 30,000 tonnes of wastewater (effluent), and 120 tonnes of waste paint per year [5.5i].

Initial research focussed on the chemistry of particle removal from paint waste, through the addition of the key reagents of aluminium sulfate and polyclay, and on the importance of pH control. This research was carried out using a jar test in the Crown Paints analytical development laboratory. The understanding of how reagent dosing influenced the flocculation of the particulate waste was assisted through technical advice and drew on equipment provided by Process Instruments [5.4]. This important link between the companies was inaugurated by Fielden, as Principal Investigator to both research programmes, who realised the potential benefits to the Crown Paints project of the more effective particle-sensing technology developed by PI.

This detailed understanding allowed trials and optimisation of a modified dosing chemistry to be carried out (in particular, determination of the minimum amounts required of aluminium sulfate and polyclay to deliver efficient flocculation) within the treatment plants at Darwen and Hull. Consequently, the dosing chemistry practices were changed at both Darwen and Hull (affecting over a million litres of paint manufactured each week across the two sites) based on the KTP studies, grounded in the technical expertise provided by Process Instruments and the research expertise of Fielden and Martin from Lancaster University, which has given an annual saving in reagent costs of GBP113,000 pa. [5.6]. This may be broken down into Darwen: (GBP20,000 pa caustic washings; GBP10,000 pa polymer washings; GBP5,000 pa in lower polyclay dosing; GBP18,000 pa in the reduction of plant washing due to increased process efficiency) and Hull: (GBP40,000 pa in reduced polyclay and aluminium sulfate consumption due to optimisation of the reagent formulation in waste filter cake generation).

4.3 Fundamental research into the optimisation of the flocculation chemistry and the improved efficiency of dewatering by filter press.

Novel benchtop apparatus, designed and constructed by Fielden and Martin, allowed for systematic research by Crown and Lancaster University into the interplay between the reagent chemistry and a range of particle-laden paint waste from representative streams at the Darwen and Hull plants). This apparatus provided detailed data of the dewatering process, which led to the development of a mathematical model that could evaluate the compression data to yield the key physicochemical parameters of yield stress and diffusivity of the solid “cake” waste generated by the dewatering process [3.5]. The outcome of this fundamental research was an optimised formulation for the Crown Paints Effluent Treatment Plants.

Thanks to the insights granted by the benchtop test apparatus, alternative dewatering processes were considered as part of the KTP programme, including ultrasonic sedimentation and centrifugation. Centrifugation was considered the closest competitor to the filter press, which resulted in a 6-month evaluation of a pilot centrifuge system by Crown at their Darwen site. This study showed that the filter press was the most efficient dewatering technology for the removal of particulates from paint waste. Subsequently, the wastewater treatment plant at the Darwen site was renewed at a cost of GBP55,000, and at the Hull site for GBP70,000 to reflect the outcome of the main element of the KTP programme [5.6].

4.4 Applied research into the recycling of solid paint waste leading to a reduction is waste production

Another project investigated both the recycling of the paint waste “cake” generated by the filter press and the water filtrate. The cake waste is currently sent to landfill but has been shown through the KTP programme to have applications as a “bulking” agent in the manufacture of external masonry paint, which is being acted on by the company to “to realise the economic and environmental benefits” [5.5i-ii]. Laboratory-scale research showed that recycled water from the filter press process could be used in the manufacture of magnolia paint (the major paint type manufactured by the company) without detrimental effects on the paint colour and opacity. This finding has already shaped Crown’s knowledge of the process, has helped to reduce waste production in the paint manufacturing of particular products, and is being rolled out across Crown’s large-scale, complex manufacturing process which includes over a million litres of paint produced weekly [5.5i-ii] and [5.6].

Unplanned in the original KTP programme, it became apparent that the partnership between Crown and Lancaster University could also benefit the company through access to specialist equipment at the Chemistry Department at LU. Specifically, the polymer development scientists benefitted from access to our Field-Emission Scanning Electron Microscope (Jeol JSM-7800F plus Oxford Instruments Xmax-50 EDS) with which they were able to evaluate novel emulsion paint formulations for the structure of the emulsion and the distribution of fillers, such as TiO₂ [5.6]. Whilst it is difficult to quantify this element of impact, the findings have been presented to the parent Hempel Group by Craig Wood, and represent a new approach to the evaluation of future paint formulations, referenced in recent company reports as having, and the diagnosis of the failure of paint formulations [5.5ii and 5.6].