CN1186779A

CN1186779A - New technology for treating waste water by lime causticization

Info

Publication number: CN1186779A
Application number: CN96123502A
Authority: CN
Inventors: 王钦河
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-12-31
Filing date: 1996-12-31
Publication date: 1998-07-08
Anticipated expiration: 2016-12-31
Also published as: CN1087004C

Abstract

The treating technology is suitable for treating waste water containing suspension and colloid and it is adding lime and CO2 gas into waste water. Through physical and chemical reaction, the hydrophilic radical in suspension is destroyed, the suspension produces precipitate together with CaCO3 and solid matter is separated from liquid for elimination. The said method is especially suitable for treating waste water from paper making plant adopting chemical pulp making process, and it is also suitable for treating waste water from milk product, food product, leather product producers.

Description

Novel process for treating waste water by lime causticization method

The invention relates to an environment protection process, in particular to an industrial wastewater treatment process. It is a new process for treating organic waste water by causticizing neutralization reaction with lime, and is specially applicable to waste water treatment in lime paper mill.

At present, many small and medium-sized paper mills are available at home and abroad, most of the small and medium-sized paper mills adopt lime process for pulping and making paper, the generated waste water seriously pollutes the surrounding environment, and the production, life and body health of people are greatly threatened, so that the country treats the sewage generated by some small and medium-sized paper mills withserious pollution for a long time. In view of the situation, many small and medium-sized plants generally treat organic wastewater by using various processes such as flocculation with inorganic and inorganic flocculants, air floatation, sedimentation, aeration oxidation, biological oxidation, etc. These methods generally have long operation period, high cost, large occupied land area, large capital investment, poor economic benefit and unsatisfactory effect, so that the methods are difficult to adopt in medium and small sized paper mills. The wastewater still seriously pollutes water areas such as rivers, lakes and seas and pollutes air, so that the health of people is seriously harmed all the time, therefore, the country is forced to stop part of factories which seriously pollute the environment, thereby causing great economic loss, and leading the factories to be irresistible to be opened.

The invention aims to overcome the defects of the prior art and provide a novel wastewater treatment process, the organic matters of the wastewater treated by the novel wastewater treatment process can be reduced by about 95 percent, the full closed-loop circulation of production is realized, and the wastewater can reach the national specified discharge standard after further exposure.

The task of the invention is implemented in the following way: a new process for causticizing waste water with lime features that a certain quantity of lime is added to organic waste water to make it saturated or supersaturated; after being stirred evenly, CO is introduced₂Gas, after reaction, CaCO is formed₃↓, which destroys the suspended state of the organic matter and the specific gravity of the hydrophilic radical, thereby generating precipitation and separating solid and liquid matters; the wastewater treatment process is carried out at normal temperature and normal pressure, and the main reaction equation is as follows:

(1)

(2)

(3)

compared with the prior art, the invention has the following advantages:

1. the invention uses high-efficiency and low-price precipitator through physical and chemical reactions, thereby achieving the purposes of precipitating impurities in the wastewater and solid-liquid separation.

2. The equipment is simple, the investment is low, the treatment capacity is large, the operation cost is low, and the use effect is good; the clearance rate of the waste water is about 95 percent, and zero discharge or most of the waste water reaching the standard can be achieved in a factory.

3. The clear water after precipitation can be returned to the factory for production, and can also be pumped into an aeration oxidation pond, and is discharged after the oxidation reaches the standard.

4. The precipitate is filtered and calcined to obtain high-quality lime which can be reused.

5. The method also has good treatment effect on other organic wastewater, such as organic wastewater discharged by food, dairy products, leather products and the like.

The present invention will be described in further detail by way of examples below:

the principle of the invention is as follows: the waste water of paper mill produced by lime method contains lignin, fiber and fine suspended particles, and the organic matter will deteriorate, decay and smell for a long time,and produce harmful substance to pollute environment. The organic substances in the waste water are Ca and partial hydroxyl groups of lignin, fiber and other organic substances separated from paper raw materials (such as wood or grass) by lime causticization in the pulping process⁺⁺The reaction produces hydrophilic colloid which forms hydrophilic group and has small specific gravity, so that it is not easy to precipitate, and in particular, some microfine fibres are easy to suspend in water, so that when the waste water is treated, lime (or flocculant) is added to increase Ca content in the waste water⁺⁺Concentration and hydrophilic groups, and then filling a large amount of CO₂After the gas is generated, the chemical reaction is generated, and Ca in the hydrophilic groups of the organic matters⁺⁺With Ca in the wastewater⁺⁺Generates CaCO₃And ↓toform water insoluble carbonate, which can be separated out in great amount and attached to organic matter to increase specific weight and destroy hydrophilic colloid state to form common precipitate for solid and liquid phase separation. Because of CaCO₃The particles of ↓ are small, the total surface area is large, and the micro organic and inorganic matters in the water can be adsorbed in a large amount to precipitate, so that the water becomes clear, and the purpose of wastewater treatment is achieved. The wastewater treated by the method is reacted at normal temperature and normal pressure, and the main reaction equation is as follows:

the implementation process comprises the following steps:

1. discharging the waste watertoThe reservoir is first filled with emulsified Ca (OH) with super concentration₂The solution is stirred to reach saturation or supersaturation.

2. After being stirred evenly, CO can be introduced₂Gas, reacting with Ca (OH) in water₂Reaction to produce CaCO₃And ↓, after the reaction is finished, the natural sedimentation can be finished after about half an hour, and the clearance rate reaches about 95 percent.

3. The clear water after precipitation can be recovered and reused for production. Or pumping into an aeration oxidation tank, and discharging after the oxidation reaches the standard.

Claims

1. A new process for causticizing waste water with lime features that a certain quantity of lime is added to organic waste water to make it saturated or supersaturated; after being stirred evenly, CO is introduced₂Gas, after reaction, CaCO is formed₃↓, which destroys the suspended state of the organic matter and the specific gravity of the hydrophilic radical, thereby generating precipitation and separating solid and liquid matters; the wastewater treatment process is carried out at normal temperature and normal pressure, and the main reaction equation is as follows:

(1)

(2)

(3)