• Tertiary filtration of wastewater from chemical manufacturer
• Toveko Continuous Moving Bed Sand Filters supplied in SAF 2205 duplex alloy
• Target value for suspended solids is 20 mg/l

Project Need

Requirement for tertiary filtration to improve the quality of the effluent from treatment plant handling wastewater arising from various manufacturing processes in the factory.

Since 1915, Hickson & Welch have been synthesising organic chemical intermediates and have two principal businesses involved in contract manufacture and the production of fine chemical intermediates for a very wide range of applications including pharmaceuticals manufacture and dye & pigment production.

At their manufacturing site in Castleford, they have a treatment plant to handle the wastewater arising from the various production processes within the factory. The plant is owned and operated by BOC Gases. Since the company’s products are organic chemicals, the heart of the wastewater treatment plant involves biological reduction of the relatively high oxygen demand continued in up to 150m 3 of wastewater entering the plant every hour. Due to the nature of the manufacturing processes, the quality of the incoming wastewater is rather variable, which can affect the operational efficiency of the treatment plant.

Organo supplied two TOVEKO continuous gravity sand filters to provide tertiary filtration of the treated wastewater prior to its final discharge to river. The filters (an S-600 and a T-1200) were supplied in SAF 2205 duplex alloy to provide long-term resistance against corrosion by the relatively high chloride concentration present.

The filtration system was designed to handle flow rates varying from 75 – 150m 3 per hour with solids concentration varying from 75 – 250mg/l. The target value for suspended solids is 20mg/l.

Prior to placing the contract for the filters with Organo, BOC Gases undertook an extended trial of the TOVEKO filter using a test unit. The results persuaded both BOC and Hickson & Welch that TOVEKO filters were the best solution for this application. One of the factors that influenced this decision is the ability of TOVEKO filters to react to changes in inlet solids load by automatically changing the rate at which the sand is removed from the filter bed and washed, thereby ensuring that the filter operates at peak efficiency at all times.

Key Elements

• 2 No Sand Filters (S-600 and a T-1200)
• Wash water pumps
• Control Panel
• Compressor
• O & M Manuals