Increasing water reuse at a client site to reduce operating costs

Since taking over the operation and maintenance of the wastewater treatment plant for a large food manufacturer in Tilmanstone - where over 70% of water is recycled for on-site reuse as part of their sustainable operation practices—Alpheus has focused on delivering optimal performance, reliability, and compliance.

As part of our ongoing commitment to operational optimisation and sustainability, we conducted a comprehensive review of the treatment process. This identified a key opportunity to enhance efficiency by reusing some of the rejected water from the WWTP’s final nanofiltration (NF) process to clean the two duty/standby drum screens to reduce reliance on towns water and reduce discharge costs.

Project Goals

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As part of a review water usage tests indicated that the two inlet screens use an average of 76 m3/day of water. We proposed that a solution to divert some of the rejected nanofiltration (NF) water to clean the screens would save the client in the region of £60 per year, through a reduction in water supply and trade effluent cost. With an investment of just under £90k, the estimated payback for the project is 16 months.

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Although this water is a by-product of the nanofiltration process, it has undergone extensive treatment - including screening, balancing, Dissolved Air Flotation, biological treatment, and ultrafiltration - before reaching this stage. This makes it highly suitable for controlled cleaning and a far better alternative to simply discharging it when a beneficial on-site use is available.

Design and Build Services Provided

Design basis

To achieve the diversion of 76m3/day of rejected Nanofiltration water for screen washing, a solution was designed to incorporate:

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A Booster set pump with a flow rate of 13.3m3/h at 9.5 bar pressure and 24 litres expansion vessel with isolating valves on the suction and isolating, and non-return valves on the discharge of each pump
A control panel and pressure switch
A break tank with a 1.5 m3 nominal capacity, float valve and low-level sensor.
A reinforced concrete plinth to support the break tank.
Pipework that would incorporate trace heating and lagging.

Delivery and Installation

Alpheus managed the supply and installation of the solution, including overseeing mechanical and electrical works whilst ensuring continuous plant operations.

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The treatment plant remained fully operational throughout the works, with Alpheus managing the works to ensure continued normal operation.
The new booster set and break tank were installed near the V-notch tank to enable gravitational overflow.
High-level pipework was connected to collect reject water from the NF discharge pipe and fitted with a manual valve to control inlet flow.
The new break tank was connected to the existing town line piping with an additional backup top-up line and float valve to maintain water delivery, where reject NF water is insufficient.
The vertical tank design shape ensures gravity takes the overflow from the break tank to the V-notch.
A brief shutdown of the mains water line to the rotary screens was required whilst connections were being made to the new line with the reject water.

The Outcome

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After completion of successful commissioning tests, the project was delivered safely, on time and within budget.

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The initial week of operation confirmed the reuse of greater than 76 m3 of water per day, which will lead to financial savings on mains water and discharge costs of around £164 per day – or £60k per year. After an investment of just under £90k, the targeted payback period of less than a year and a half should be easily achieved.

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As the outsourced operator of the plant, Alpheus will continue to maintain and operate the new system to maximise its performance and asset lifespan.

Increasing water reuse at a client site to reduce operating costs

Project Goals

Design and Build Services Provided

Design basis

Delivery and Installation

The Outcome

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