Acid production from lead smelting flue gas; high COD levels in the wastewater after purification
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The wastewater fed into our plant for treatment is waste acid generated from the purification of acid produced via lead smelting flue gas; the water used for purification and supplementation comes from rainwater as well as water recovered from cleaning floors and equipment. The sulfurization-lime neutralization-iron salt method is employed for wastewater treatment. Before 2008, the annual lead production volume was 30,000 tons, but it increased to 80,000 tons after technical upgrades; however, the wastewater treatment facilities were not upgraded accordingly. The quality of the incoming wastewater consists of As at levels of 80–500 mg/L, Cd at 30–80 mg/L, and F at 1,500–2,200 mg/L. Previously, the COD level in the water was always low, but last year it suddenly rose to around 2000, and this issue has not been resolved to date. In a previous attempt, a small sample of water was taken and inflated using an air compressor at a rate of 1 m³/min for 2 hours; testing before and after showed that there was basically no change in the COD level. Please ask an expert for advice; thanks.
What is the PH? What’s the BOD level? The biochemical quality is too poor, so aeration isn’t very effective
The pH value is around 1-2. BOD has not been measured due to logistical constraints; if the biodegradability is poor, what are some ways to address this issue?
With such a low pH, aeration is not very effective. Try iron-carbon electrolysis, or Fenton’s process
Thank you for your answer; I’ll give it a try when I get back.
By the way, the pH of the water after treatment is kept between 7 and 9; at this point the COD level is high. Is there any simple method for treating such wastewater?
Uh, I’ll try to handle it myself – is there anyone skilled who can help?:)
Smelting wastewater is generally not suitable for treatment using biochemical methods in the initial stage; its treatment relies mainly on physicochemical approaches, such as adjusting the pH value or adding certain ions that react with metal ions to form precipitates, which are then removed through solid-liquid separation. If organic matter is present in the wastewater, biochemical treatment must be carried out after removing metal ions or certain special ions such as fluoride ions.