Water conservation

Case studies

1. West African Brewery

A study was carried out in a West African Brewery were the water to product ratio was 30 to 40. This should more typically be 15 to 20 for this region and type of brewery and preferably closer to 10.

An assessment of the plant users was made and water consumption for each area either measured or estimated. Several areas were identified as high water users based on design data or previous experience of similar equipment. Process modifications were made to the bottle washers, pasteurisers and CIP operations to reduce water use.
A water balance was carried out across the site and it was discovered that there was a significant difference between the measured water being pumped to the site from the boreholes and the estimated water consumption on the plant.
Further investigations led to the discovery of several underground water mains failures accounting for a significant quantity of the water overuse.


2. Caribbean Brewery 1

This brewery used both mains water and a reverse osmosis (RO) treated well water. Although the general water usage was low. (water to product ratio of 12) the water costs were high because of the high usage and unit cost of mains water.
A survey of the site uses was carried out and it was proposed to provide R O water to all possible areas in place of mains water. The RO plant was unreliable and badly designed and maintained. Modifications were made to the operation and design of the plant which increased the reliability and drastically reduced the operating costs . A different antiscalent and cleaning chemicals were used resulting in cheaper less frequent cleans and the membranes were replaced with ultra low pressure membranes which produced a 2 year payback on electricity cost savings alone. In addition, water usage was reduced by recycling wort cooling liquor and a fully automated CIP plant was installed with rinse water reuse. The annual savings in water costs were of the order of £100,000 p.a


3. Caribbean Brewery 2

This brewery used a substantial amount of water (Reverse Osmosis treated and softened water) for wort cooling and boiler make up . It was established that the wort chiller was inefficient and needed replacing. Condensate could not be returned easily because the plant was using an old pressurised steam dearator/hotwell and the pressure was too high to return the condensate. The excess treated water used for wort cooling was recycled as boiler feed make up and secondly a new atmospheric hotwell was installed to enable condensate to be returned.


4. Alumina Producers

This production facility was wasting a lot of secondary condensate because of sporadic process contamination. After some very expensive boiler tube failures caused by this contamination the site decided to dump all of the condensate and to make up the difference using treated mains water at a rate of 100 m3/hr. This solved the problem but was very expensive in terms of water and effluent costs. A scheme was designed to monitor and treat the condensate which was at high temperature and had caustic and organic contamination using ultrafiltration and TOC monitoring.