Project Background

The original electrolytic aluminum flue gas desulfurization system is not equipped with desulfurization wastewater treatment system. The desulfurization wastewater is discharged into the sewage treatment system of the whole plant after comprehensive treatment. Due to the high suspended solids content and high TDS content of desulfurization wastewater, it has a great impact on the original sewage treatment system of the whole plant. In order to meet the treatment requirements and reduce the environmental protection risk, the company will build a desulfurization wastewater treatment system in 2022 in the renovation project of ultra-clean discharge of electrolytic aluminum flue gas.

The overall process is as follows: the desulfurization wastewater is pumped into the primary HDCY integrated desulfurization wastewater treatment system, through the addition of lime and integrated adsorption flocculant, the suspended solids in the effluent are guaranteed to be ≤ 70ppm, at the same time, the fluoride content in the water is pretreated to control its fluoride content ≤ 15mg/L, and the desulfurization wastewater treatment system is fed into the secondary HDCY integrated desulfurization wastewater treatment system, the effluent fluoride shall be ≤ 5mg/L, and the content of suspended solids shall be ≤ 50mg/L. The clean water shall be supplied to the clean water tank for reuse or discharge. The sludge shall be pumped to the gypsum dewatering belt machine for dehydration and then transported out together with the desulfurization gypsum to realize comprehensive utilization.

To achieve the effect

The effect of the modified desulfurization wastewater treatment system:

1) Stable operating conditions, strong impact resistance to fluctuations in influent suspended solids, which can ensure stable operation in the range of influent SS 0-100000mg/L, fluoride ≤ 200mg/L, and effluent SS ≤ 50mg/L fluoride ≤ 50mg/L;

2) The effluent water quality is stable, and the overflow water after HDCY integrated desulfurization wastewater treatment is stable to meet the implementation requirements of the new standard (indirect discharge limit) in Table 2 of the GB25465-2010 Pollutant Discharge Standard for Aluminum Industry;

3) The pharmaceutical system is simple, the process flow is simplified, and the whole process flow runs automatically without personnel intervention;

4) The underflow sludge does not need to be treated separately, and is directly pumped to the gypsum dehydration system to complete dehydration, simplifying the process flow and improving the reliability of operation.