Alkaline and silty wastewater treatment at Tummel Bridge Station, Pitlochry
Background
Global Infrastructure were tasked with demolishing concrete inside a generator house to allow for refurbishment. The work generates water continuously which needs to be collected and pumped to maintain a dry working area. The water mixing with the fine concrete particles results in an effluent with an elevated pH of around 11 and contains a significant suspended solids loading.
Overall Objective
Dewater the work area, treat the alkaline water with CO2 to correct the pH to a near neutral pH7 and settle out the suspended solids prior to safely discharging to the environment.
Solution
A small submersible pump in a sump transfers water from the active work area to the Siltbuster pH correction and settlement system positioned outside. The DS4 unit equipped with a CO2 vaporiser and pH probe automatically doses CO2 to adjust the pH to a near-neutral setpoint in the mixing chamber. The flow rate and therefore residence time in the chamber is important to provide enough contact time to with the CO2 for pH correction before overflowing into the FB50 lamella clarifier.
The precipitant from the pH adjustment and the solids already in the water from the sump can settle out as the water is slowly distributed across the lamella plates. The solids collect in the bottom of the FB50 unit and clean water overflows from the weir to the discharge point. The solids in the sludge hopper are routinely decanted for optimum performance.
