The Problem

This effluent arises from a range of processes on site which are combined prior to treatment on a conventional clarifier. The major issue was suspended solids and these were finely dispersed and they were historically difficult to treat.

These typically have ranged from 150 to 350 mg/l against a discharge limit of 100 mg/l.

The Solution

Vale Water introduced a number of key changes to the treatment process and also introduced a balance tank prior to the clarifier which enabled the pH to be monitored and controlled more closely.

Vale Water introduced a combination of the “ValePac“ and the “ValeF” series of products into the regime as well as changing the “ValeFloc” series polymer to a higher charge.

The Result

The changes have resulted in a significant reduction in suspended solids to within the discharge limit of 100 mg/l combined with improved performance of the filter press as a result of the reduction in the sludge production with the new chemical regime.

The Future

As part of the review undertaken by Vale Water work is now focussed on reducing the quantity of “lost” raw material into the effluent stream and also moving towards a fully automated control system to replace the current manual operation.