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Wastewater from surface treatments

By 8 September 2016case, mechanical, pcf

The Client
Our Client is a company with a certified quality production process, working at an International level since 1960. They produce seamless cold-drawn steel tubes according to EN 10305-1 and welded cold-drawn precision steel tubes according to EN 10305-2, for automotive, hydraulic and mechanical applications.

The Challenge
The main requirements of the customer, usually found as one of the major problems for all the players of this sector, were related to the use of a chemical-physical wastewater treatment plant that did not allow to comply with the discharge limits required by law and producing a significant amount of sludge, with high operating costs, particularly due to the need to maintain the plant constantly monitored.

The Solution provided

We provided the customer with a ZLD solution (zero liquid discharge) that allows to reuse both the distillate and the concentrate, respecting the local environmental regulations and dramatically reducing the disposal costs and the presence of operational staff dedicated to monitoring system.
The sulfuric acid base pickling washing water is treated with a vacuum heat pump evaporator EVALED® PC E 12000.
The phosphating washing water is treated with an evaporator with mechanical recompression of the vapour EVALED® TC 15 000 AA.

Results & Benefits
The distillate obtained by the treatment of the sulfuric acid base pickling washing water, about 90% of the initial flow, is reused for new washing, while the concentrate is sent again to the bath and regenerated with a crystallizer that allows the separation of iron and offers the opportunity to obtain ferrous sulfate intended for sale. Total zero discharge.

The distillate obtained by the treatment of the phosphating washing water, about 90% of the initial stream, is recovered for new washing, while the concentrate is sent again to the baths to be reused. In the bath tanks, a filtering system of a mechanical type operates to keep clean the solution, avoiding the formation of precipitates. Total zero discharge.

Phosphating washing water analysis

Parameters (UM) Effluent Distillate Concentrate
Phosphorus (ppm) 150 <5 1600
Dry matter (%) 0,4 5
Heavy metals (ppm) 600 <0,1 7000
Conductivity (uScm) 2700 30