Iron oxide red wastewater treatment and recycling of iron-containing sludge

The paper presents a wastewater treatment process and recycling of iron sludge from wastewater treatment for iron oxide red production. Results show that: (1) Sludge from wastewater treatment process under the operating parameters: 1.84 g/L of NaOH dosage, 10 mins of aeration with flow rate of 1 L/min and 150 mins of sediment time is potential for seed crystal preparation and excellent iron oxide red product can be obtained in the secondary oxidation under condition of 85 °C, 68 h of reaction time and 150 mL/min of airflow rate, (2) In practical engineering, the average removal rate of Fe2+ and SS and chroma of effluent is 99.75%, 86.7% and less than 40 times, respectively, and all items of product satisfy demands of industrial standards, (3) Compared with the original wastewater treatment, the new process can save the cost of wastewater treatment and earn extra 20.0 dollars for a ton of iron oxide red product and then both economic benefit and environmental protection can be realized by this process. It is proved that the novel method is reliable, economical and promising in iron oxide red industry and cleaner production of iron oxide red is feasible.