CN107445390A - A kind of " three-stage process " biodegradation method for being used to administer heavy metal - Google Patents

Abstract

The invention discloses a "three-stage method" biodegradation method for treating heavy metals. The treatment steps are as follows: 1) Enter the discharged heavy metal wastewater from the bottom of the straw tank into the straw tank, and properly control the flow rate of the water inflow to ensure 3 hours 2) The clear liquid flowing out from the straw trough enters the constructed wetland system, and uses its unique substrate-plant-microbial ecosystem to reduce heavy metals in wastewater through adsorption, precipitation and enrichment; 3 ) The wastewater treated by the constructed wetland system enters the aerobic pool, and the heavy metal content in the wastewater is further reduced through surface complexation, biosorption and flocculation of microorganisms in the activated sludge in the pool. The invention adopts the three-stage biodegradation method of "abandoned straw-aquatic plants-microbes" to treat heavy metal wastewater, effectively utilizes agricultural waste, has low cost, thoroughly treats heavy metals, is environmentally friendly and has no secondary pollution, and has simple process and convenient operation and management.

Description

A "three-stage method" biodegradation method for treating heavy metals

technical field

The invention relates to the field of heavy metal sewage treatment, in particular to a "three-stage method" biodegradation method for treating heavy metals.

Background technique

At present, heavy metal wastewater has a wide range of sources and a large amount of water. Heavy metal wastewater mainly comes from industries such as electroplating, mining, chemical industry, electrolysis, pesticides, medicine, tobacco, paint, and pigments. This type of wastewater has the characteristics of long-term toxic effects and non-biological degradation. It enters the human body through the food chain and accumulates in the human body, causing various diseases and dysfunction, and finally causing serious harm to human health. With the rapid development of my country's industry, a large amount of heavy metal wastewater is discharged, and heavy metal pollution is becoming more and more serious. How to effectively treat and recycle it has become a common concern of people.

There are three commonly used methods for heavy metal treatment: 1) chemical method, by adding chemicals to convert heavy metal ions into precipitates, thereby removing them. This method has high treatment efficiency for high-concentration heavy metal wastewater, and it is easy to produce harmful by-products, and a large amount of waste residue is generated to cause secondary pollution; 2) Physical and chemical methods, which do not change the chemical form of heavy metals in wastewater, and can be adsorbed and concentrated , separation, and even recycling, but the treatment cost is high and it is difficult to be widely used; 3) biological method, through the adsorption, flocculation and enrichment of heavy metal ions in water by organisms and their derivatives to remove them. The biological method has a strong ability to adsorb and transform heavy metal ions, and has good tolerance to organic matter. When the organic matter pollution is ≤5000mg/L, it will not affect the adsorption of heavy metal ions; it has the characteristics of economy, high efficiency, and environmental protection, but it is only suitable for medium Low concentration heavy metal wastewater treatment. The existing single heavy metal wastewater treatment method has various deficiencies, and one or several methods need to be used in combination to solve the problem of heavy metal pollution more effectively.

my country is a big agricultural country, and the agricultural waste produced every year is as high as hundreds of millions of tons. Most of these wastes are directly discarded, and some are incinerated, which has a great impact on the environment, production and life. However, there have been a large number of researches on the treatment of wastewater by agricultural waste in foreign countries. Agricultural waste has a high porosity and a large specific surface area, which can physically adsorb metal ions. The main components of agricultural waste are cellulose, hemicellulose, and wood. The surface of pectin and pectin contains a large number of active groups, such as carboxyl, hydroxyl, etc. These active groups can be combined with heavy metal ions through ion exchange, chelation, etc., to achieve the purpose of removing heavy metal ions. In order to make this kind of natural organic adsorbent have a better adsorption capacity, it is necessary to introduce more active groups such as hydroxyl, carboxyl, sulfhydryl, phosphate, amine through chemical modification, such as citric acid modification, alkalization treatment, sulfhydryl, etc. modified etc. As a highly efficient natural organic adsorbent, the chemically modified agricultural waste not only recycles agricultural waste and reduces environmental pollution, but also has abundant raw material sources, many varieties, low cost, large adsorption capacity, and high adsorption capacity. The equipment is simple and the product is easy to degrade, which has a broader market prospect than activated carbon with good adsorption performance but expensive price.

Contents of the invention

The technical problem solved by the present invention is to provide a "three-stage method" biodegradation method for treating heavy metals, so as to solve the above-mentioned shortcomings in the background technology.

The technical problem solved by the present invention is achieved by the following technical solutions: a "three-stage method" biodegradation method for treating heavy metals, the processing steps are as follows:

1) A straw tank is provided at the outlet of the heavy metal waste water tank with a heavy metal content of 50-500mg/L, and the heavy metal waste water discharged from the heavy metal waste water tank will enter the straw tank from the bottom of the straw tank, and the The flow rate of the heavy metal wastewater is controlled to ensure an effective adsorption time of 3 hours; 2) The clear liquid flowing out from the straw tank enters the constructed wetland system, and the substrate-plant-microbial ecosystem in the constructed wetland system will be absorbed through adsorption, precipitation 3) the treated wastewater in the constructed wetland system further enters the aerobic pool, and microorganisms are cultivated in the activated sludge in the aerobic pool, and the sludge in the aerobic pool is inoculated The volume is 20% of the tank volume, the tank is continuously aerated, the dissolved oxygen is controlled to 2-4mg/L, the pH is adjusted to 6.5-8.5, and the hydraulic retention time is set to 10-24 hours according to the content of organic matter in the heavy metal wastewater. Through the surface complexation, biosorption and flocculation of microorganisms in the activated sludge in the pool, the heavy metal content in the wastewater is further reduced, so that it can stably meet the first-level standard of the "Comprehensive Wastewater Discharge Standard".

In the present invention, further, the straw trough can be put in a kind of agricultural waste from corn stalks, wheat straws, peanut shells, sugar beet pulp or rice husks, and these agricultural wastes are subjected to primary cutting treatment, these In order to make this kind of natural organic adsorbents have better adsorption capacity, the treated agricultural wastes are subjected to secondary treatment through chemical modification methods such as citric acid modification, alkalization treatment and sulfhydryl modification. Introduce more active groups of hydroxyl, carboxyl, mercapto, phosphate, and amine into these agricultural wastes.

In the present invention, further, the wetland substrate in the constructed wetland system is composed of gravel and soil at a ratio of 1:1, and the aquatic plants planted on the wetland substrate are composed of reeds, cattails, cannas, Composed of windmill grass, through the physical precipitation, filtration, chemical precipitation, adsorption, microbial interaction and absorption of plants in the constructed wetland, the effective removal of heavy metals is realized.

In the present invention, further, after the heavy metal wastewater is absorbed, precipitated and enriched by "abandoned straw-aquatic plants", the heavy metal content is far lower than the first-level standard of the "Comprehensive Wastewater Discharge Standard".

Beneficial effects of the present invention:

1. The present invention adopts the "waste straw-aquatic plant-microbe" three-stage biodegradation technology to treat medium and low concentration heavy metal wastewater, through the efficient adsorption of modified straw, the absorption and enrichment of aquatic plants and the complexation of microorganisms in the aerobic pool The synergistic effect of , metabolism and biological flocculation can reduce the heavy metals in the wastewater to an extremely low level, and the whole process is environmentally friendly without secondary pollution, the process is simple, and the operation and management are convenient.

2. As a new environment-friendly bio-adsorption material, the modified crop straw has a rich pore structure, a huge specific surface area, and good adsorption performance. It also has the advantages of a wide range of raw material sources, low cost, and easy biodegradation. The utilization of agricultural waste resources reduces environmental pollution.

Description of drawings

Fig. 1 is a schematic diagram of a "three-stage method" biodegradation method for controlling heavy metals according to the present invention.

detailed description

In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the present invention will be further described below in conjunction with specific illustrations.

Embodiment: As shown in Figure 1, implementation method: a kind of " three-stage method " biodegradation method for controlling heavy metal, its steps are as follows:

1. The heavy metal wastewater is fed from the bottom of the straw tank, and the flow rate is controlled to ensure an effective adsorption time of 3 hours. In order to improve the adsorption performance of straw, it needs to be chemically modified to increase its active groups;

2. The clear liquid flowing out of the straw trough enters the constructed wetland system, and uses its unique substrate-plant-microbial ecosystem to reduce heavy metals in wastewater through adsorption, precipitation and enrichment;

3. Then enter the aerobic pool, and further reduce the heavy metal content through the surface complexation, biosorption and flocculation of microorganisms in the activated sludge to meet the discharge standard.

The heavy metal content in the heavy metal wastewater treated in the step 1 is between 50-500mg/L.

In the first step, the straw trough can be put into a kind of agricultural waste such as corn stalks, wheat straws, peanut shells, beet pulp or rice husks, which are cut into small pieces of about 5 cm. The main components of agricultural waste, cellulose, hemicellulose, lignin and pectin, contain a large number of active groups on the surface, such as carboxyl, hydroxyl, etc. These active groups can combine with heavy metal ions through ion exchange, chelation, etc. to achieve The purpose of removing heavy metal ions. In order to make this kind of natural organic adsorbent have a better adsorption capacity, it is necessary to introduce more active groups such as hydroxyl, carboxyl, sulfhydryl, phosphate, amine through chemical modification, such as citric acid modification, alkalization treatment, sulfhydryl, etc. modified etc.

In the second step, the constructed wetland matrix is composed of gravel and soil at a ratio of 1:1, and the aquatic plants are composed of reeds, cattails, cannas, windmills, etc., which have a strong ability to absorb heavy metals. The effective removal of heavy metals is achieved through physical precipitation, filtration, chemical precipitation, adsorption, microbial interaction, and plant absorption in constructed wetlands. According to the concentration of heavy metal wastewater, the residence time of the constructed wetland can be adjusted to 20-48h.

In the third step, after the heavy metal wastewater is absorbed, precipitated and enriched by "abandoned straw-aquatic plants", the concentration of heavy metals is significantly reduced, and then the heavy metals can be reduced to an extremely low level under the action of microorganisms in the aerobic pool. The amount of sludge inoculum in the aerobic tank is 20% of the tank volume, the tank is continuously aerated, the dissolved oxygen is controlled at 2-4mg/L, the pH is adjusted to 6.5-8.5, and the hydraulic retention time is set to 10-24 hours.

Above shows and described basic principle of the present invention and main feature and the advantage of the present invention, those skilled in the art should understand that, the present invention is not limited by above-mentioned embodiment, what described in above-mentioned embodiment and specification sheet just illustrates the present invention Principle, under the premise of not departing from the spirit and scope of the present invention, the present invention also has various changes and improvements, and these changes and improvements all fall within the claimed scope of the present invention, and the claimed protection scope of the present invention is defined by the appended claims Requirements and their equivalents are defined.

Claims (3)

1. A "three-stage method" biodegradation method for controlling heavy metals is characterized in that the processing steps are as follows: 1) A straw tank is provided at the outlet of the heavy metal waste water tank with a heavy metal content of 50-500mg/L, and the heavy metal waste water discharged from the heavy metal waste water tank will enter the straw tank from the bottom of the straw tank, and the The flow rate of heavy metal wastewater is controlled to ensure an effective adsorption time of 3 hours; 2) The clear liquid flowing out from the straw trough enters the constructed wetland system, and the substrate-plant-microbial ecosystem in the constructed wetland system will reduce the heavy metals in the wastewater through adsorption, precipitation and enrichment; 3) The treated waste water in the artificial wetland system further enters the aerobic pool, and microorganisms are cultivated in the activated sludge in the aerobic pool. Aeration, control the dissolved oxygen 2-4mg/L, adjust the pH to 6.5-8.5, and set the hydraulic retention time to 10-24 hours according to the content of organic matter in the heavy metal wastewater. Through the surface complexation, biosorption and flocculation of microorganisms in the activated sludge in the pool, the heavy metal content in the wastewater is further reduced, so that it can stably meet the first-level standard of the "Comprehensive Wastewater Discharge Standard". 2. A "three-stage method" biodegradation method for controlling heavy metals according to claim 1, characterized in that: corn stalks, wheat straws, peanut shells, sugar beet pulp or rice stalks can be placed in the straw tank. A kind of agricultural waste in the shell, these agricultural wastes are subjected to primary cutting treatment, these processed agricultural wastes are used to make this kind of natural organic adsorbent have a better adsorption capacity, and these agricultural wastes are processed at the same time The secondary treatment involves introducing more hydroxyl, carboxyl, sulfhydryl, phosphate, and amine active groups into these agricultural wastes through chemical modification methods such as citric acid modification, alkalization treatment, and sulfhydryl modification. 3. A kind of " three-stage method " biodegradation method that is used to control heavy metal according to claim 1, it is characterized in that: the wetland substrate in the said artificial wetland system is made up of gravel, soil by 1:1, in said The aquatic plants planted on the wetland substrate are composed of reeds, cattails, cannas, and windmill grasses that have strong absorption capacity for heavy metals. Through the physical precipitation, filtration, chemical precipitation, adsorption, microbial interaction and plant absorption of the constructed wetland, heavy metals can be realized. effective removal.