Treatment of Steel Cold Rolling Wastewater

This wastewater treatment plant is located to the north of the main cold rolling plant building, occupying a total area of 107m×62m. The wastewater is discharged through a wastewater pipe channel for each process production line to the wastewater treatment plant. The wastewater streams containing acid, chromium, concentrated oil & emulsion and diluted oil wastewater.

The wastewater can be divided into 5 main wastewater streams containing neutral salt & chromium, acid, concentrated alkaline & emulsion, diluted alkaline & oil, and finishing wastewater.

This project is divided into two construction phases with the total discharge of wastewater in both phases shown as follows:

Phase one wastewater treatment plant
chromium wastewater: 30m³/h
acid wastewater: 120m³/h
Sludge treatment: installed two filter presses during phase one, and one filter press during phase two.
The waste water containing neutral salt and chromium is first treated with waste acid or NaHSO₃ to reduce the Cr⁶⁺ to Cr³⁺, and then mixed with acidic wastewater for further treatment.
Acidic wastewater is first treated by aeration to oxidize Fe²⁺ to Fe³⁺; then lime is used as a neutralizer to form hydroxide metal participates.
All imported equipment for the phase one project has been? in operation since Aug 27, 2007 and meets the discharge standards shown below:

Phase two wastewater treatment plant
Phase two wastewater treatment plant is now the design stage for concentrated alkali emulsion, diluted alkali oil, and finishing wastewater treatment system, the treatment capacity are as follows:
concentrated alkali emulsion：18m³/h
diluted alkali oil： 110m³/h
finishing wastewater： 12m³/h
The wastewater is mainly treated with ultra-filtration, CAF, bio-treatment, and MRB, all equipments and measuring devices will be imported, the treated wastewater is anticipated to meet the follows standards:

In conclusion
MEEG is responsible for the process flow, the automation and other basic to detail designs, purchasing all equipment, installation, commissioning, and etc. Following the Ningbo Baoxin Stainless Steel Co and Jinan Iron and Steel Co., this project is another large scale steel mill wastewater treatment system project for our company; it is also one of our milestones in steel mill wastewater treatment industry.