“LIKE WATCHING PAINT DRY”: WATER RECYCLING IN THE PAINT INDUSTRY : Using chemistry to design & develop processes, which will help to create a "circular economy" in paint manufacturing

Wardrop, Joshua Thomas Lees and Fielden, Peter and Martin, Alastair and Platel, Rachel and Coote, Ian and Demaine, Rachel and Bowker, David (2022) “LIKE WATCHING PAINT DRY”: WATER RECYCLING IN THE PAINT INDUSTRY : Using chemistry to design & develop processes, which will help to create a "circular economy" in paint manufacturing. PhD thesis, Lancaster University.

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This thesis represents the cumulation of an industrially based project (KTP 10134) to find resource within manufacturing waste and develop a circular economy within industry. This work documents this collaborative project between Lancaster University’s Chemistry and Engineering departments and an industrial partner (Crown Paints), highlighting specific milestones and outcomes of the project which may be of interest to wider industry and academia. The manufacture of aqueous based paint (also known as emulsion, water based or latex paint) produces large volumes of waste, the largest stream by far is industrial effluent (estimated at Crown Paints alone to be approx. 30,000,000 l annually); produced primarily from the washing of production vessels. Crown Paints is a leading UK based decorative paint manufacturer and part of the global Hempel Group. Crown Paints operates two production sites situated in Hull and Darwen, UK. The Hull site produces much more aqueous-based product and produces a larger volume of effluent waste (16,000 m3, 2015). Currently, this effluent is pre-treated at each of the two sites’ effluent plants, which flocculate any particulates producing an inert filtercake, which is currently sent for disposal in landfill. To fully assess the paint manufacturing process, from a waste generation perspective a simple Value Stream Analysis (VSA) of the process was performed. This uses an already established Lean Six Sigma tool (i.e., VSA), which was applied from a unique wastewater perspective. Thus, a novel environmental application of VSA for establishing the origin of excessive water useage in industrial processes is presented. Laboratory based modelling (via jar testing) of the current coagulation and flocculation based effluent process and subsequent plant trials suggested an ability to reduce the consumable useage of flocculant by 50%. To improve the laboratory testing further and to focus on the filtration aspect of the process a novel automated stepped pressure filtration method was developed. This included an innovative design of a filtration apparatus and a new method to further characterise the process of filtration. The data interpretation method presented applies a multi-step systematic approach, with each step supported by statistical justification, to characterise filter cake particle stress, filtration diffusivity and cake hydraulic resistivity from a single stepped pressure experiment. Experimentally this new method showed no impact of the 50% flocculant reduction on the filtration parameters of interest. Additionally, it was also shown that the raw effluent could be utilised as the “solvent” within the paint production process with limited effect on the paint’s physical properties. From laboratory testing this was scaled to production volumes (circa. 9,000-19,000 l) and a method was developed to reduce virgin raw materials by up to 5%. A production batch (9,000 l) with 4% extra product (360 l) was produced. Testing of this trial batch showed no difference with a standardised paint formulation. This presents an exciting opportunity for water reuse within various Fast Moving Consumer Goods (FMCG) manufacturing processes.

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Thesis (PhD)
Uncontrolled Keywords:
?? flocculationcoagulationeffluentwaterwastewatereffluent treatmentwater treatmentwastewater treatmentwater reusesolid liquid separationfiltration and separationfiltrationfilterpressfiltercakestepped pressure filtrationyield stressresistivitydiffusibilityfil ??
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26 Sep 2022 11:25
Last Modified:
16 Mar 2024 00:06