CN101693575A - Ferrate pre-oxidation-bioactivity filter combined water treatment method - Google Patents

Abstract

The invention provides a ferrate preoxidation-biologically active filter combined water treatment method. First, add ferrate to pre-oxidize the slightly polluted water body. The dosage of ferrate is controlled at 0.3-1.5mg/L, and the pre-oxidation time is 5-30min; The top of the pond flows in, and the bottom flows out. The upper layer of the biologically active filter is an activated carbon layer with a height of 60-80cm, and the lower layer is a quartz sand layer with a filtration rate of 6-9m/h. The invention includes various processes such as chemical oxidation, adsorption, biological oxidation, etc. It can be applied in water supply treatment without changing the existing process flow, without adding large equipment, and showing good efficiency in removing organic pollutants. It is a project suitable for my country's national conditions. , Enhanced conventional pollution removal technology that can improve drinking water quality economically and with low consumption.

Description

Ferrate preoxidation-biologically active filter combined water treatment method

(1) Technical field

The invention relates to a treatment method, which is a water treatment method suitable for the transformation of old water plants.

(2) Background technology

Affected by the discharge of industrial wastewater and domestic sewage, the quality of drinking water sources in my country has gradually deteriorated. The pollution components in water are mainly organic matter containing natural organic and inorganic components. Among them, many trace organic pollutants are the most difficult to remove, which is very harmful to human health. In addition, the increase in the content of ammonia nitrogen and other pollutants in water also seriously affects Pollution removal efficiency of water treatment processes.

Activated carbon has been widely used in the advanced treatment of drinking water due to its well-developed pore structure, which can effectively adsorb organic matter. However, activated carbon has limited adsorption capacity and short service life, so it needs to be regenerated and replaced frequently. Aiming at the weakness of activated carbon, researchers use pre-oxidation method to improve the adsorption performance of activated carbon. Among them, the combination of ozone oxidation and biological activated carbon technology is the purification method of micro-polluted water commonly used in the world at present, that is, the micro-polluted water is firstly oxidized by ozone, and some organic matter is initially degraded, and the organic matter in the water is easily degraded by microorganisms. The ratio is increased, the biodegradability is improved, and then further purified by the bioactivated carbon method. However, there are certain problems in the actual application of the ozone oxidation process: (1) the investment in the ozone oxidation process equipment is large, the operating cost is relatively high, and the maintenance and management are complicated; (2) the high concentration of ozone will cause harm to the human body, and the ozone Exhaust gas needs to be strictly treated; (3) When the raw water contains bromide, it will form bromate harmful to human body under the oxidation of ozone. Bromate is classified as 2B level by the International Agency for Research on Cancer (higher carcinogenic possibility ), these deficiencies limit the application of the ozone process.

Ferrate is a new type of water treatment agent developed since the 1970s. Compared with ozone, ferrate is a hexavalent iron salt, which has strong oxidizing properties, especially under acidic conditions. Its standard oxidation-reduction potential (+2.20V) is higher than that of ozone (+2.07V), which is The most oxidizing oxidizing agent currently used in water and wastewater treatment. In addition, during the oxidation process, ferrate itself is reduced to a new substance Fe ³⁺ or (Fe(OH) ₃ ), and the product can be further hydrolyzed and has a coagulation effect. It is a good inorganic flocculant and can efficiently Remove fine suspended solids from water. Not only that, during the whole water disinfection and purification process, ferrate will not produce any harmful substances such as chloroform, and will not introduce secondary pollution of harmful organisms. Therefore, ferrate, as a dual-effect green new water treatment agent with strong oxidizing and coagulating effects, has attracted extensive attention of researchers.

Public reports related to the present invention are: 1, "ozone biological activated carbon process advanced treatment of slightly polluted raw water" ("Environmental Science and Technology", 2009, 32 (7): 125-127); 2, "chemical preoxidation/biological Activated carbon to remove ammonia nitrogen in slightly polluted raw water" ("Water Treatment Technology", 2005, 31(10): 37-39); 3. The application number is 03107814.1, and the name is "Permanganate pre-oxidation and biological activated carbon combined to remove pollution Process" patent documents, etc.

(3) Contents of the invention

The purpose of the present invention is to provide a ferrate preoxidation-biologically active filter combined water treatment method that reduces the cost of the entire water treatment process while ensuring the safety of effluent.

The purpose of the present invention is achieved like this:

First, a certain amount of ferrate is added to pretreat slightly polluted water. Ferrate is added at the front end of the coagulation process, which can simultaneously play the dual role of oxidizing organic pollutants and strengthening coagulation. It can be added by wet method or directly by dry method. According to the water pollution, the dosage of ferrate is controlled at 0.3-1.5mg/L, the pre-oxidation time is 5-30min, and the coagulation is added after pre-oxidation agent for coagulation and sedimentation;

The pre-oxidized precipitated water flows in from the top of the biologically active filter and flows out from the bottom. The biologically active filter is transformed from a quartz sand filter, and the upper layer of quartz sand is replaced by fine-grained activated carbon. The height of the activated carbon layer is It is 60-80cm, and the lower quartz sand layer is reserved, and its height is 10-40cm. The modified bioactive filter strengthens the filtration process.

The present invention may also include:

1. The activated carbon in the activated carbon layer is fine granular activated carbon with a particle size of 5-80 mesh.

2. The activated carbon in the activated carbon layer is fine granular activated carbon with a particle size of 5-60 mesh.

The present invention replaces the ozone oxidation process with ferrate and combines it with the biologically active filter process to provide a ferrate-biologically active filter process for treating micro-polluted water bodies. The cost of the treatment process.

In the present invention, it is necessary to determine whether to add an aeration device before the biologically active filter according to the pollution degree of the raw water. It is generally believed that the removal effect of the biologically activated carbon process will be affected when the dissolved oxygen concentration in the effluent of the biologically activated carbon is lower than 2.0mg/L, so , the dissolved oxygen concentration in the effluent of the biological activated carbon filter can be used as a monitoring index to measure whether aeration is required.

Owing to adopting above-mentioned technical scheme, the present invention has following beneficial effect:

1. Ferrate has strong oxidizing properties, which can effectively decompose the pollutants in the polluted water body and reduce the pollutant content.

2. Ferrate is reduced to Fe ³⁺ or (Fe(OH) ₃ ) during the oxidation process, and the product is further hydrolyzed to have the effect of coagulation, without any toxic side effects, and will not cause any secondary pollution to the water body.

3. The equipment required for the ferrate oxidation process includes stirring, dosing and metering equipment, etc. The equipment is simple and easy to automatically control. The bioactive filter is transformed on the basis of the original sand filter, which can not only ensure the effect of the filter on turbidity removal, but also enable the filter to have the ability to remove ammonia nitrogen, nitrite nitrogen and organic matter, and has an empty bed It has the advantages of short contact time, small footprint and high processing efficiency. Therefore, the combination technology of ferrate pre-oxidation and bioactive filter has the characteristics of no need to add large equipment, less capital investment, low operating cost, and high treatment efficiency, and is suitable for the construction of new water plants and the transformation of old water plants Features;

4. This technology is suitable for the treatment of water bodies with different pollution degrees, with good effect and wide application range.

The combined process of ferrate pre-oxidation and biological active filter includes chemical oxidation, adsorption, biological oxidation and other processes. It can be used in water treatment without changing the existing process flow and without adding large equipment, showing good removal efficiency. The efficiency of organic pollutants is an enhanced conventional pollution removal technology that is suitable for my country's national conditions and can improve the quality of drinking water economically and with low consumption.

(4) Description of drawings

Fig. 1 is a process flow diagram of the present invention;

Figure 2 is a schematic diagram of the structure of a biologically active filter.

(5) Specific implementation methods

The following examples describe the present invention in more detail:

Embodiment: Taking a certain surface water as the source water of the experiment, the water body is seriously polluted, wherein the typical pollutants are ammonia nitrogen 0.8mg/L, COD _Mn 7.5mg/L, and the smell is earthy (V).

The polluted water body was treated by the combination process of ferrate preoxidation and bioactive filter.

First, add ferrate for pre-oxidation before the coagulation process, the dosage is 1.0mg/L, dosing in dry method, pre-oxidation time is 30min, after pre-oxidation, add aluminum sulfate for coagulation, coagulant The dosage is 25~30mg/L. The specific coagulation conditions are as follows: fast stirring for 1 min, with a rotation speed of 200-300 rpm; slow stirring for 10 min, with a rotation speed of 60 rpm; and a precipitation time of 30-45 min.

The precipitated water treated by ferrate oxidation is used as the influent of the biologically active filter. The biologically active filter is transformed from an ordinary sand filter. The upper layer of quartz sand is replaced by granular activated carbon 1. The biological activated carbon is fine-grained activated carbon with a particle size of 6-9 mesh and a height of 80cm. The lower layer of quartz sand 2 is retained. The height is 10cm, and the filtration rate is 6m/h. An aeration device is installed on the top of the biologically active filter to meet the demand of microorganisms for dissolved oxygen in the biological process. The backwash of the biologically active filter is washed with separate water, and the expansion height of the filter layer is 30%.

After the polluted water is treated by the ferrate-biologically active filter, the effluent quality meets the requirements of the "Drinking Water Sanitation Standard", including ammonia nitrogen 0.05mg/L, COD _Mn 1.15mg/L, and no smell.

The ferrate pre-oxidation and bioactive filter process improved the decontamination efficiency of the coagulation process and the filtration process respectively, and at the same time, the ferrate pre-oxidation can significantly improve the decontamination performance of the subsequent bioactive filter, thereby improving the pollution of the overall process. The removal of pollutants improves the safety of drinking water quality. The specific performance is:

(1) Long-term operation under high turbidity conditions will shorten the service life of activated carbon, which requires certain pretreatment of the influent of the biological activated carbon filter. The ferrate composite agent has the function of strengthening coagulation, which can effectively remove large particles and colloidal particles in water, and reduce the impact of particles on the subsequent biological activated carbon process.

(2) The ferrate and bioactive filter had a synergistic effect on the removal of organic matter with different molecular weights. The use of ferrate pre-oxidation can improve the coagulation effect and the removal efficiency of the coagulation process for macromolecular organic matter; while the biological treatment unit can significantly remove small molecular organic matter. From the perspective of molecular weight, the combined process of ferrate preoxidation and biological activated carbon has certain complementarity to the removal of organic matter. The combination of these two processes is helpful for the removal of organic matter with different molecular weights and improves the removal efficiency of the whole process for organic matter. .

(3) Ferrate pre-oxidation can convert some macromolecular organic matter into small molecular organic matter, which improves the biodegradability of raw water, promotes the biodegradation efficiency of the subsequent bioactive filter process, and is conducive to improving the pollution removal efficiency of the overall process.

(4) The redox product of ferrate, Fe ³⁺ , is a trace element necessary for the growth of microorganisms, which can stimulate the growth of microorganisms in the subsequent bioactive filter, especially significantly increasing the activity and quantity of nitrifying bacteria, thus strengthening the biological activity The nitrogen removal function of the filter.

Claims (3)

1. Ferrate Pre-Oxidation Positive-bioactivity filter combined water treatment method, it is characterized in that: at first, add ferrate micropollutant water is carried out preoxidation, the dosage of ferrate is controlled at 0.3-1.5mg/L, and preoxidation time is 5-30min; Through the water of pre-oxidation treatment, flow into from the bioactivity filter top, flow out the bottom, and the upper strata of described bioactivity filter is an active carbon layer, and the active carbon layer height is 60-80cm, and lower floor is a quartz sand layer, filtering velocity is 6-9m/h.

2. Ferrate Pre-Oxidation Positive-bioactivity filter combined water treatment method according to claim 1 is characterized in that: the gac of described active carbon layer is the fine particle gac, and its granularity is the 10-80 order.

3. Ferrate Pre-Oxidation Positive-bioactivity filter combined water treatment method according to claim 2 is characterized in that: the gac of described active carbon layer is the fine particle gac, and its granularity is the 10-60 order.

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