4 Cases to Help You Solve the Problem of Inorganic Waste Acid Treatment

1. Current Situation of Waste Acid Treatment

According to statistics, China produces over 100 million tons of waste acid annually, of which about 40 million tons of waste acid of various concentrations are generated by chemical industries such as electroplating, metallurgy, and surface treatment. Among them, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid are the main ones. These acid washes have strong acidity (pH<1), and if they enter the natural world, they pose great harm to groundwater, soil, and disrupt ecological balance.

The traditional neutralization precipitation method is not only expensive and incomplete in treatment, but also cannot recycle acid, resulting in resource waste. The methods of recycling include heating evaporation method, extraction method, permeable membrane method, etc. These methods have disadvantages such as high processing cost, high maintenance cost, and complex operation steps (as shown in the table below). Compared with these methods, adsorption method has obvious advantages.

Table 1 Comparison of Various Governance Methods

Method	Characteristic	Shortcoming
Zhonghe Law	Simple operation, reliable technology, and pH value compliant discharge	Generate a large amount of solid slag and require subsequent treatment; For highly acidic waste acids, the treatment cost is high
Extraction method	Good separation effect	High technical requirements and complex operation steps; Suitable extractants are difficult to obtain and have high operating costs
Evaporation concentration method	Mature technology, high concentration of recovered acid	High requirements for equipment, requiring corrosion-resistant materials; Equipment is prone to scaling and requires frequent cleaning
Spray roasting	No secondary pollution, high regeneration rate of hydrochloric acid	Large land area and high investment; Consuming a large amount of cooling water, electricity, fuel, etc., resulting in high operating costs

2. Technical Introduction

Our company's independently developed inorganic acid adsorbent is used for efficient separation of acids and metal ions. By utilizing the high selectivity of the adsorbent for inorganic acids, inorganic acids are adsorbed during the adsorption process, while metal ions can pass through. The adsorbed inorganic acids can be regenerated and recovered with water. The final acid and metal ions are effectively separated and recycled separately. The material has a long service life and low operating costs.

Process Flow Diagram

Figure 1 Process Flow Diagram

3. Technical Features

Short process flow and easy operation.
Low energy consumption, treated at room temperature, improves the service life of equipment.
Good separation effect, capable of achieving a recovery rate of over 90% for inorganic acids.
Less post maintenance and lower operating costs.

4. Application Cases

The treatment requirement for nickel containing waste acid produced by a chemical plant manufacturer in Shandong is to separate nickel from acid. Our company adopts adsorption method to achieve efficient separation of nickel and acid. The effluent is nickel salt, which is recovered after appropriate treatment. The purified acid solution obtained by pure water desorption can be reused in the production process. This solution has significant economic benefits, not only solving the problem of concentrated waste acid treatment, but also saving acid consumption in production for manufacturers.

Table 2 Data before and after waste acid treatment

Source	Water volume (m³/day)	Sulphuric acid	Nickel ion (mg/L)	Colour
Original waste acid	100	20%	7860	Blue
Effluent	100	2%	6680	Blue
Purified acid	100	18%	1180	Near colorless

Treatment effect (from left to right, the original waste acid, effluent, purified acid)

Figure 2 Treatment effect (from left to right, the original waste acid, effluent, purified acid)

A certain enterprise in Jiangsu province produces waste acid containing lead and iron, and the treatment requirements are as follows: lead and iron are separated. Our company uses adsorption method to achieve efficient separation of lead and iron. Finally, the lead acid containing liquid is recovered, and the iron acid containing liquid is used as a water purification agent.

Table 3 Data before and after waste acid treatment

Source	Water volume (m³/day)	Lead ion (mg/L)	Iron ion (mg/L)	Colour
Original waste acid	10	1080	50000	Dark yellow
Effluent	10	<150	45000	Light yellow

The treatment requirements for copper containing waste acid generated by a chemical plant in Henan are as follows: 3. The treatment requirements for copper containing waste acid generated by a chemical plant in Henan are: copper ≤ 500mg/L, COD ≤ 3300mg/L. Our company adopts a two-step adsorption method, first using special copper removal adsorbents to remove copper, and then using organic matter removal adsorbents to remove COD. The final effluent can be reused in production.

Table 4 Data before and after waste acid treatment

Source	Water volume (m³/day)	COD(mg/L)	Acidity (calculated as HCI)	Copper	Appearance
Original waste acid	200	-23000	17%	-5000 mg/L	Green
Effluent	200	1865	14%	6	Colourless

Treatment effect diagram (including raw water, copper removal effluent, and organic matter removal effluent in sequence)

Figure 3 Treatment effect diagram (including raw water, copper removal effluent, and organic matter removal effluent in sequence)

A chemical plant in Jiangsu Province produces waste acid using concentrated sulfuric acid as a catalyst. The treatment requirements are: COD ≤ 3500mg/L, sulfuric acid recovery, and concentration step carbonization. Our company uses adsorption method to remove organic matter, and the effluent is reused in catalyst production.

Table 5 Data before and after waste acid treatment

Source	Water volume (m³/day)	COD(mg/L)	Sulfuric acid	Organic compound	Appearance
Original waste acid	22	-29000	35-40%	2.50%	Orange yellow color
Effluent	22	<2800	35-40%	Not detected	Colourless