Acidic and Leady effluent @ 3.5m³/hr

1.0 Process

To treat leady and acidic effluent.

2.0 Process description

The effluent from the manufacturing centre is separated into two streams.

Streams must be kept separately from the manufacturing centre to the effluent plant.

Equipment can be sited in or out of doors and consist of holding pits, treatment modules, settlement module, pumping, filtration, lead removal and other associated pipe work and valves. The control console is sited close to the effluent plant and protected against weather conditions.

The following descriptions of the treatment process may be read in conjunction with our flow diagram.

Stream 1 - Acid Effluent 3.0 m³/Hour.

Flow of effluent from the manufacturing centre is piped or channeled to flow by gravity to the effluent treatment area, where is enters a suitable holding pit. Effluent is continuously stirred, and transferred at a slow continuous rate via a pump to the first neutralisation module

Effluent is continuously stirred and an addition of calcium hydroxide under pH control is added to neutralise a strong acid to approximately 2-4pH. Effluent will then overflow into the second neutralisation where it is continuously stirred and calcium hydroxide is added automatically under pH control. Effluent once again gravitates to the next stage flocculation tank where an addition of polyelectrolyte is added via a dosing pump so to precipitate the metal ions in the settlement module.

Effluent flows by gravity into a flat bottom settlement tank where all sludge will be concentrated and removed by tanker and disposed of by local authorities.

All clear water overflows to the pH adjustment tank to correct the pH to a value of approx. 6 which would be carried out by the addition of HCl and pH control. Effluent overflows to the pumping module  from which it is transferred automatically through the automatic sand filter through two deionisation columns and into the water storage tank. Clean water would be utilised for the rinsing of cation, sand filter and also back to service as per requirements. Tank is complete with an overflow facility so that if too much water is produced it will automatically overflow to discharge.

All backwash water from the sand filter will flow back to the flocculation tank. All regeneration water from the deionisation will flow to the acid pit .

Stream 2 - Leady Effluent 0.5 m³/hr.

Flow of effluent from the manufacturing centre is piped or channeled to flow by gravity to a suitable holding pit. Effluent is continuously stirred and transferred at a slow continuous rate by a pump to the settlement tank. Lead particles will settle in the bottom conical portion of the tank whilst clear water will overflow over the top of the tank in the peripheral weir and flow to flocculation tank for further treatment.

The sludge will be pumped at slow rate and at a predetermined time to an SG tank in the SG tank, which is continuously stirred and the SG adjusted by adding water and lead particles until the correct SG is achieved from which it will be pumped through a loop pipe work to the paste mixer as production requires. 

REAGENTS.

Calcium hydroxide reagent will be made up in one of two tanks which will be continuously and transferred to the second tank for continuous pumping through a recirculation loop and drawn off automatically by the pH signals in the neutralisation stage (2) and (3).

Flocculation would be made in thank which is continuously stirred and is pumped by a flow dosing pump directly into the flocculation tank.

Regeneration tank to be utilised in conjunction with the cation unit for lead removal at tanks and  hydrochloric acid and calcium hydroxide would be utilised and pumped via a dosing pump directly to the deionisation unit. The hydrochloric acid will be further utilised to dose pH adjustment tank.

3.0 Discharge limits

 4.0 Service requirements