Arsenic removal process for acid wastewater

Abstract

The invention discloses an arsenic removal process for acid wastewater, and belongs to the technical field of smelting engineering sewage treatment processes. Comprising the following steps: adding a proper amount of potassium permanganate into an acidic wastewater stock solution, and stirring to react for 30 minutes; adding lime milk, adjusting the pH value to 2.0-2.5, stirring and reacting for 30 minutes, sampling and analyzing As; adding a proper amount of sodium sulfide, stirring and reacting for 30 minutes, sampling and analyzing As; lime milk is added, the pH value is adjusted to 10-11, stirring reaction is conducted for 30 min, filtering is conducted, and filtrate is taken to analyze As; a proper amount of potassium permanganate and ferrous sulfate are added into the filtrate, the pH value is adjusted back to 7-8 through the ferrous sulfate, meanwhile, a 3 # agent solution is added, the mixture is stirred to react for 30 min, a clarified solution is taken to analyze As, the pH value of production water is adjusted back to 7 through concentrated sulfuric acid, and the S-002 type biological agent is added and liquid returning treatment can serve as follow-up safeguard measures. According to the method, the requirements of discharge limits of heavy metals such as As, Cu, Pb, Zn, Cd and Hg in the acid wastewater can be met, the first-pass yield of the acid wastewater is increased to 99.2% from 93%, and the first-pass rate of arsenic in the acid wastewater is increased to 99.8% from 48%.

Description

Technical Field

[0001] The invention relates to the technical field of smelting engineering sewage treatment technology, and in particular to an acidic wastewater arsenic removal process. Background Art

[0002] Currently, the lime-iron salt, sulfide, and sodium hydrosulfide methods have low arsenic removal rates, and the treated arsenic levels fail to meet the special emission limit requirements. The As content in the waste acid after treatment using existing processes is approximately 5 mg / l, far below the special emission limit requirement of less than 0.1 mg / l. Optimizing the acidic wastewater treatment process will improve arsenic removal efficiency and reduce treatment costs, directly lowering a company's operating costs and improving its economic benefits. Furthermore, reducing the generation of secondary pollutants can also avoid the risks of fines and compensation faced by companies due to environmental pollution. The successful implementation of the acidic wastewater treatment system process optimization project can promote the progress and development of environmental protection efforts as a whole.

[0003] The research objectives and significance of the acidic wastewater treatment system process optimization technology research project are significant. It not only helps resolve arsenic contamination in acidic wastewater, improves arsenic removal efficiency, and promotes technological innovation, but also has significant environmental, economic, and social benefits. Therefore, conducting research on an optimized process for arsenic removal from acidic wastewater has significant economic and social significance for the economic, rational, and efficient utilization of energy and resources, turning harm into benefit, and advancing environmental protection efforts. Summary of the Invention

[0004] The object of the present invention is to provide a process for removing arsenic from acidic wastewater, thereby solving the problems raised in the background technology.

[0005] The technical solution adopted in the present invention is as follows: A process for removing arsenic from acidic wastewater comprises the following steps: Step 1: Preprocessing Add appropriate amount of potassium permanganate to the acidic wastewater solution and stir to react for 30 minutes; Step 2: Neutralization Add lime milk, adjust the pH to 2.0-2.5, stir and react for 30 minutes, and take samples for As analysis; Step 3: One-time arsenic removal Add appropriate amount of sodium sulfide, stir and react for 30 minutes, and take samples for analysis of As; Step 4: Secondary Neutralization Add lime milk, adjust the pH to 10-11, stir and react for 30 minutes, filter, and analyze the filtrate for As; Step 5: Secondary arsenic removal Add appropriate amount of potassium permanganate and ferrous sulfate to the filtrate, use ferrous sulfate to adjust the pH value back to 7-8, add 3# agent solution at the same time, stir and react for 30 minutes, take the clarified liquid for As analysis; adjust the pH value of the produced water back to 7 with concentrated sulfuric acid, add S-002 type biological agent and return liquid treatment as subsequent protection measures.

[0006] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention, implemented in a wastewater treatment plant, has yielded significant results in improving the first-pass compliance rate for acidic wastewater, reducing production costs, and reducing the amount of acidic wastewater discharged. This method not only meets the emission limits for heavy metals such as As, Cu, Pb, Zn, Cd, and Hg in acidic wastewater, but also increases the first-pass rate for acidic wastewater from 93% to 99.2%, and the first-pass compliance rate for arsenic in acidic wastewater from 48% to 99.8%. This invention successfully addresses the bottleneck issue of removing arsenic above 10 mg / l in acidic wastewater, effectively improving the compliance rate for arsenic in zinc smelting acidic wastewater.

[0007] The present invention has found widespread application in various industries, including non-ferrous metal smelting and the chemical industry. In particular, copper and zinc smelting processes generate large amounts of arsenic-containing acidic wastewater. If discharged directly without treatment, this acidic wastewater can cause serious environmental pollution. Therefore, the application of this acidic wastewater arsenic removal process in the copper and zinc smelting industry is particularly important. The reagents selected in the present invention offer high cost-effectiveness, excellent arsenic removal efficiency, low production costs, and a simple and easy-to-implement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a process flow chart of the present invention; DETAILED DESCRIPTION

[0009] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0010] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0011] The arsenic content of the acidic wastewater in the present invention is: As: 100-500 mg / l. Example 1

[0012] like Figure 1 This embodiment provides a process for removing arsenic from acidic wastewater. The main component content of the acidic wastewater in this embodiment is: As: 300 mg / l. The process includes the following specific steps: (1) First, prepare 1L of arsenic removal reagent with a 16% concentration of a mixture of potassium permanganate and iron salt; add 0.69g of potassium permanganate reagent to 1L of acidic wastewater stock solution for pretreatment, and stir the reaction for 30min; (2) Add lime milk to the pretreated acidic wastewater for neutralization, stir thoroughly for 30 minutes to react, adjust the final pH value of the acidic wastewater to 2, and sample and analyze the As content of the acidic wastewater to 18.75 mg / l; (3) Add 1.43 g of sodium sulfide reagent to the neutralized acidic wastewater for arsenic removal. Stir the reaction for 30 minutes. Sampling and analysis of the acidic wastewater showed an As content of 7.66 mg / l. (4) The acidic wastewater in (3) was neutralized twice with lime milk, and the pH value was adjusted to 11. The mixture was stirred for 30 min and filtered. The filtrate was analyzed for As content, which was 1.4 mg / l.

[0013] (5) Secondary arsenic removal: add 8.67 ml of arsenic removal reagent to the filtrate, adjust the pH value back to 7 with ferrous sulfate, and at the same time add flocculant solution to accelerate sedimentation. Stir the reaction for 30 minutes, and take the clarified liquid for analysis. As 0.027 mg / l; adjust the pH value of the produced water back to 7 with concentrated sulfuric acid. Add S-002 biological agent and return liquid treatment as subsequent safeguard measures.

[0014] Finally, after the acidic wastewater is treated as above, production water that meets the standards is obtained.

[0015] The arsenic content in the production water was detected to be: As: 0.027 mg / l. Example 2

[0016] This embodiment provides a process for removing arsenic from acidic wastewater. The main component content of the acidic wastewater is: As: 260 mg / l. The process includes the following specific steps: (1) First, prepare 1L of arsenic removal reagent with a 16% concentration of a mixture of potassium permanganate and iron salt; add 1.4g of potassium permanganate reagent to 2L of acidic wastewater stock solution for pretreatment, and stir the reaction for 60min; (2) Add lime milk to the pretreated acidic wastewater for neutralization, stir thoroughly for 60 minutes to react, adjust the final pH value of the acidic wastewater to 2.5, and sample and analyze the As content in the acidic wastewater to 15.32 mg / l; (3) Add 2.9 g of sodium sulfide reagent to the neutralized acidic wastewater to remove arsenic. Stir the reaction for 60 min. Sampling and analysis of the acidic wastewater showed an As content of 4.35 mg / l. (4) The acidic wastewater in (3) was neutralized twice with lime milk, and the pH value was adjusted to 10. The mixture was stirred for 60 min and filtered. The filtrate was analyzed for As content, which was 1.22 mg / l.

[0017] (5) Secondary arsenic removal: add 17.35 ml of arsenic removal reagent to the filtrate, adjust the pH value back to 7 with ferrous sulfate, and at the same time add flocculant solution to accelerate sedimentation. Stir the reaction for 60 minutes, take the clarified liquid for analysis and find As 0.011 mg / l. Add concentrated sulfuric acid to adjust the pH value of the produced water back to 7. Add S-002 biological agent and return liquid treatment as subsequent safeguard measures.

[0018] Finally, after the acidic wastewater is treated as above, production water that meets the standards is obtained.

[0019] The arsenic content in the production water was detected to be: As: 0.011 mg / l.

Claims

1. A process for removing arsenic from acidic wastewater, characterized in that: The following steps are involved: Step 1: Preprocessing Add appropriate amount of potassium permanganate to the acidic wastewater solution and stir to react for 30 minutes; Step 2: Neutralization Add lime milk, adjust the pH to 2.0-2.5, stir and react for 30 minutes, and take samples for As analysis; Step 3: One-time arsenic removal Add appropriate amount of sodium sulfide, stir and react for 30 minutes, and take samples for analysis of As; Step 4: Secondary Neutralization Add lime milk, adjust the pH to 10-11, stir and react for 30 minutes, filter, and analyze the filtrate for As; Step 5: Secondary arsenic removal Add appropriate amount of potassium permanganate and ferrous sulfate to the filtrate, use ferrous sulfate to adjust the pH value to 7-8, and add 3# agent solution at the same time, stir and react for 30 minutes, and take the clarified liquid for As analysis.

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