CN108328800A - A kind of removal waste water of heat-engine plant heavy metal ion method - Google Patents

Abstract

The invention belongs to waste water of heat-engine plant water treatment field more particularly to a kind of removal waste water of heat-engine plant heavy metal ion methods.A kind of removal waste water of heat-engine plant heavy metal ion method, this method are applied to desulfurization wastewater and are completed before entering recovery processing, be as follows：(1) desulfurization wastewater is entered into the first fluidized bed from bottom, is wherein filled with quartz sand filter media in the first fluidized bed, connection NaOH solution tank, KMnO in the bottom of the first fluidized bed₄NaOH solution tank NaOH, while desulfurization wastewater enters the first fluidized bed from bottom, NaOH solution, KMnO₄Solution enters the first fluidized bed together from first fluidized bed bottom；Conventionally the pH in the first fluidized bed is controlled between 7.5~11.The sludge density that the method for the invention enables the technique to generate reaches 2.5~3.0kg/L, and dewatered moisture is less than 20%, and compared with the traditional chemical precipitation method, the sludge quantity that fluidized bed process generates will be less than 25%.

Description

A method for removing heavy metal ions from thermal power plant wastewater

technical field

The invention belongs to the field of thermal power plant wastewater treatment, and in particular relates to a method for removing heavy metal ions from thermal power plant wastewater.

Background technique

Heavy metals in industrial wastewater are the most harmful to the environment. After heavy metal wastewater undergoes multiple metal chemical and electrochemical processes, metal elements such as zinc, copper, chromium, nickel, and cadmium in the water appear in atomic valence and are directly discharged into the environment. , will endanger people's health through long-term cumulative effects. Minamata disease and Pain disease are caused by mercury-containing and cadmium-containing wastewater polluting the environment respectively. Therefore, effective measures must be taken to deal with heavy metal wastewater.

The wastewater containing heavy metal ions in thermal power plants is mainly desulfurization wastewater, which contains a large amount of heavy metal elements, such as Cr, As, Cd, Pb, Hg, Cu, etc.

The conventional treatment method is: put the desulfurization wastewater directly into the neutralization reaction tank, add alkaline substances such as NaOH or Ca(OH) ₂ into the reaction tank, and remove Fe ³⁺ , Zn ²⁺ , Ni ²⁺ , Most of the heavy metal ions such as Cu ²⁺ and Cr ³⁺ are removed by forming hydroxides; adding organic sulfur to make Hg ²⁺ and Pb ²⁺ ions in the wastewater become sulfide precipitation; adding flocculants to remove the fine and dispersed particles in the wastewater Colloidal substances condense into large particles and settle down; the coagulated wastewater enters the clarification tank for sedimentation, and the supernatant is discharged after reaching the standard, and the sludge is concentrated.

However, using the above methods to treat desulfurization wastewater requires complicated process routes, and the operating conditions of desulfurization wastewater in many power plants are not stable in the actual use control process. Therefore, it is inevitable to develop new processes to reduce operating costs and improve operational stability.

Contents of the invention

In order to effectively remove heavy metal ions in desulfurization wastewater, the present invention provides a method for removing heavy metal ions from thermal power plant desulfurization wastewater in view of the current problems of complex process routes, unstable operating conditions and the defects of solutions for removing heavy metal ions in desulfurization wastewater , using the method of the invention can conveniently control the process conditions, especially improve the safe and stable operation quality of desulfurization wastewater treatment.

A method for removing heavy metal ions from thermal power plant waste water of the present invention comprises the following steps:

A method for removing heavy metal ions from thermal power plant wastewater, which is applied to desulfurization wastewater before it enters recycling treatment, and its specific steps are as follows:

(1) Desulfurization waste water enters the first fluidized bed from the bottom, wherein the quartz sand filter material is filled in the first fluidized bed, connects NaOH solution tank, _KMnO solution tank at the bottom of the first fluidized bed, and desulfurization waste water is from When the bottom enters the first fluidized bed, NaOH solution, _KMnO Solution enters the first fluidized bed together from the bottom of the first fluidized bed; By controlling the addition of NaOH solution, the pH in the first fluidized bed is controlled at Between 7.5 and 11;

(2) The desulfurization wastewater treated in step (1) enters the second fluidized bed; the pH in the first fluidized bed is controlled between 4.5 and 7.0 by controlling the amount of NaOH solution added;

(3) The desulfurization wastewater treated in step (2) enters the buffer pool, buffers and circulates in the buffer pool, and takes samples to measure the desulfurization wastewater treated by the buffer pool at the same time. If the following conditions are all met at the same time, recycle it; Under any one condition, carry out the cycle treatment of next step; Said condition comprises: Ni content is less than 1mg/L; Cd content is less than 1.5mg/L; Zn content is less than 1mg/L; Hg content is less than 0.05mg/L;

(4) Repeat steps (1)-(3) for the desulfurization wastewater that does not meet the recovery conditions in step (3) until the desulfurization wastewater is sampled and measured to meet the recovery conditions.

Using the method of the present invention, when the desulfurization wastewater passes through the first fluidized bed, the divalent manganese ions and ferrous ions are adsorbed on the heavy metal ions dissolved in the desulfurization wastewater, and are oxidized into manganese dioxide under the action of the oxidant _KMnO and ferric hydroxide, and form a covering layer on the metal surface. Since manganese dioxide and ferric hydroxide have strong adsorption characteristics for inorganic soluble ions, by continuously increasing this covering layer, the adsorbed soluble ions are copolymerized Granules settle down to form sludge. The method of the present invention makes the sludge produced by the process reach a density of 2.5-3.0kg/L, and the moisture after dehydration is lower than 20%. Compared with the traditional chemical precipitation method, the fluidized bed method The amount of sludge produced will reach 22-25%.

Description of drawings

Fig. 1 is a schematic diagram of the connection structure of the equipment involved in the method of the present invention.

Figure 1-First fluidized bed; 2-Second fluidized bed; 3-Buffer tank; 4-KMnO ₄ solution tank; 5-NaOH solution tank.

Detailed ways

A method for removing heavy metal ions from thermal power plant wastewater, which is applied to desulfurization wastewater before it enters recycling treatment, and its specific steps are as follows:

(1) Desulfurization waste water enters the first fluidized bed 1 from the bottom, wherein the quartz sand filter material is filled in the first fluidized bed 1, and NaOH solution tank 5 and KMnO solution tank 4 are connected at the bottom of the first fluidized bed 1 , while the desulfurization waste water enters the first fluidized bed 1 from the bottom, NaOH solution and _KMnO solution enter the first fluidized bed 1 from the bottom of the first fluidized bed 1 together; The pH in the chemical bed 1 is controlled between 7.5 and 11; heavy metal ions such as Ni, Cd, and Zn in the detached wastewater are removed for the first time;

(2) The desulfurization waste water after step (1) treatment enters the second fluidized bed 2; By controlling the addition of NaOH solution, the pH in the first fluidized bed 1 is controlled between 4.5～7.0; Cl ion and Hg ions form complex complexes under the action of fluidized bed.

(3) The desulfurization wastewater treated in step (2) enters the buffer pool 3, buffers and circulates in the buffer pool 3, and simultaneously samples and measures the desulfurization wastewater treated by the buffer pool 3, and if the following conditions are all met at the same time, perform recycling treatment; If any of the conditions are not met, carry out the next step of circulation processing; said conditions include: Ni content is less than 1mg/L; Cd content is less than 1.5mg/L; Zn content is less than 1mg/L; Hg content is less than 0.05mg/L L;

(4) Repeat steps (1)-(3) for the desulfurization wastewater that does not meet the recovery conditions in step (3) until the desulfurization wastewater is sampled and measured to meet the recovery conditions.

After repeated treatment of desulfurization wastewater by the method of the present invention, the removal rates of heavy metals such as Ni, Cd, and Zn are over 99%, 92%, and 97% respectively, and the removal rate of Hg can also reach over 96%.

The system for removing heavy metal ions from thermal power plant waste water of the present invention comprises a first fluidized bed 1, a second fluidized bed 2 and a buffer pool 3 connected in sequence, wherein the first fluidized bed 1 is provided with a desulfurization waste water that links to each other At the inlet end, the NaOH solution tank 5 and the KMnO4 solution tank 4 are respectively connected to the bottom of the first fluidized bed 1 through pipelines, and the first fluidized bed 1 is filled with quartz sand filter material.

Claims (1)

1. a kind of removal waste water of heat-engine plant heavy metal ion method, it is characterised in that this method is entering back applied to desulfurization wastewater It completes, is as follows before receiving processing：

(1) desulfurization wastewater is entered into the first fluidized bed from bottom, wherein quartz sand filter media is filled in the first fluidized bed, first Bottom connection NaOH solution tank, the KMnO of fluid bed₄NaOH solution tank NaOH, while desulfurization wastewater enters the first fluidized bed from bottom, NaOH solution, KMnO₄Solution enters the first fluidized bed together from first fluidized bed bottom；By the addition for controlling NaOH solution PH in the first fluidized bed is controlled between 7.5~11；

(2) treated, and desulfurization wastewater enters second fluidized bed to step (1),；By controlling the addition of NaOH solution by first PH in fluid bed is controlled between 4.5~7.0；

(3) treated, and desulfurization wastewater enters buffer pool to step (2), the buffer cycles in buffer pool, while sampling and measuring is through slow Rush pond treated that desulfurization wastewater is recycled if the following conditions meet simultaneously；If being unsatisfactory for any of which When one condition, the circular treatment of next step is carried out；The condition includes：Ni contents are less than 1mg/L；Cd contents are less than 1.5mg/L；Zn contents are less than 1mg/L；Hg contents are less than 0.05mg/L；

(4) desulfurization wastewater that recycling condition is unsatisfactory in step (3) is repeated into step (1)-(3), until sampling and measuring desulfurization is useless Until water meets recycling condition.