Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | augusT 2014 | 15 The plant was officially opened by Baron- ess Verma, pictured above with (l-r) Wyke Farms chairman John Clothier, MD Rich Clothier, dairy supervisor David Roswell and production director Tom Clothier Project focus: Wyke Farms food industry – to draw up the plans for the new plant. "We put together a specification based on capacity demands and water quality requirements," says the compa- ny's owner, Brian Rebbeck. "The plant capacity was set at 750m³ per day, with up to 70% for reuse as potable water. In October 2012, Aquabio was selected as the technology supplier, essentially because of their energy costs. Also, the Aquabio system comprises standard, commercially available units which we could go and see in operation at a major salad producer." So, how does it work? Well, in the primary treatment stage, factory trade effluent (wash water, no human waste) passes into an underground interceptor which allows any solids to settle inside integral chambers. The wastewater then overflows from the interceptor into a balance tank – the previously deployed aeration tank – where two aeration mix- ers do their work. From here, the aer- ated effluent is pumped into an existing DAF tank to remove further suspended matter and impart pH correction. A–er DAF, secondary treatment be- gins, which is where the new Aquabio plant takes over. Firstly, the wastewater is pumped into a bioreactor (feeder tank), which holds the biomass popula- tion that breaks down organic matter. The biomass requires oxygen to operate and this is provided by a jet aeration system and air blowers. The water is then separated from the biomass using an ultra-filtration mem- brane separation system. This involves the circulation of biomass through external membrane banks. Under pres- sure, the treated effluent is produced as permeate from the membranes, with the biomass retained and returned to the bioreactor. The permeate from the membrane system is subsequently dis- charged to a UF permeate tank which provides a reservoir for UF membrane plant should be investigated to ensure adequate capacity for future increases in production, as well as provide water for re-use in the cheese factory. A–er evaluating and costing the main options, then taking into ac- count the compliance standards, land requirement, and the fact the existing plant would have to continue in use until the new facility was fully commis- sioned, it was agreed to push forward with a £1.3 million wastewater recovery plant based on membrane technology. This would feature a series of processes including aeration and dissolved air flotation (DAF), followed by a bioreac- tor stage, ultra-filtration (UF), reverse osmosis (RO) and ultraviolet (UV) disinfection, ultimately allowing the company to recover up to 95% of its factory wastewater. Wyke Farms commissioned Brian Rebbeck Technical Services – a com- pany specialising in the provision of practical advice on the statutory, fi- nancial and technical aspects of water, wastewater and waste disposal in the • Challenges ● A litre of process water is re- quired to produce each litre of milk for use in Wyke Farms' products. ● The cheese factory and local dwellings are supplied with potable water from boreholes on Wyke farmland. There is no mains supply in the area. ● Mains water had to be tankered- in to supplement borehole supply in dry periods. ● The existing wastewater treat- ment plant had seen a number of upgrades over the past 10 years but was reaching its limit as peak production increased. ● To provide tertiary treat- ment (reverse osmosis and UV disinfection) to produce potable water for re-use. ● To extend the existing wastewater treatment plant by providing further biological treatment (UF and RO membrane systems), producing high quality wastewater for discharge to the river. • Drivers

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