CN107162159A - The method that bromate generation is controlled in ozone and active carbon depth-averaged model technique - Google Patents

Abstract

The invention provides a method for controlling the generation of bromate in an ozone/activated carbon advanced water treatment process, which comprises the following steps: adding available chlorine to the raw water body, and performing ozone/activated carbon after the bromide ion in the raw water body is converted into hypobromous acid. Activated carbon advanced water treatment process. The generation method of controlling bromate in the ozone/activated carbon advanced water treatment process of the present invention overcomes the problems such as poor economy and low treatment efficiency in the prior art, and it has the characteristics of low cost, obvious control effect and simple operation, thereby It has a wide range of applications and has been applied to a certain extent in actual production.

Description

Method for controlling bromate generation in ozone/activated carbon advanced water treatment process

technical field

The invention belongs to the technical field of ozone advanced treatment, and in particular relates to a method for controlling bromate generation in an ozone/activated carbon advanced water treatment process.

Background technique

The ozone/activated carbon process is one of the most commonly used advanced treatment processes for drinking water. This process can effectively inactivate microorganisms and oxidize refractory organic matter. However, when the raw water contains bromide ions (Br ^‐ ), bromate (BrO ₃ ^‐ ), which is difficult to remove by conventional water treatment processes, will be generated after ozone oxidation. Br ^‐ concentrations of up to 1 mg/L and 80 mg/L have been reported in freshwater and seawater, respectively. In recent years, due to seawater intrusion, the concentration of Br in the raw water of water plants has increased, ^and the concentration of BrO ₃ ^- in the effluent has also increased. Studies have found that the concentration of BrO ₃ ⁱⁿ drinking water can be as high as 127 μg/L. Because BrO ₃ ^‐has a high possibility of carcinogenicity, it has been designated as a 2B-level potential carcinogen by the International Agency for Research on Cancer. According to the calculation of the risk of cancer as 1 in 10,000, a standard adult (with a body weight of 70kg and drinking 2L per day Water) can withstand a maximum concentration of BrO ₃ ^-5μg /L. The World Health Organization (WHO), the US Environmental Protection Agency (US EPA), the European Union and China all require that the concentration of BrO ₃ ^‐ in drinking water not exceed 10 μg/L. In addition, due to the scarcity of fresh water resources in many parts of China, drinking water treatment processes using desalinated seawater containing high concentrations ^of Br- as raw water are becoming more and more common.

At present, the control technologies for bromate mainly include reducing solution pH, membrane filtration, ion exchange, ammonia addition, ultraviolet irradiation and free radical scavengers. There are certain limitations in each of these methods, such as reducing the pH of the solution to control the generation of bromate in raw water containing high alkalinity requires adding a large amount of reagents, and the operating cost increases thereupon; membrane filtration and ion exchange methods, etc. In the actual production process, it is easy to suffer from membrane fouling, which leads to a decrease in water flux and increases the cost of water treatment; although the ammonia addition method controls the formation of bromate to a certain extent, it may produce toxic nitrogen-containing disinfection by-products; Ultraviolet irradiation consumes more energy and is less economical; the free radical scavenger method reduces the oxidation capacity of the oxidation system while reducing the amount of bromate generated. Lowering the solution pH method, membrane filtration method and ion exchange method are less economical, the ammonia addition method may lead to the generation of toxic nitrogen-containing disinfection by-products, the treatment cost of the ultraviolet irradiation method is relatively high, and the free radical scavenger method is effective in reducing bromine. Therefore, how to control the generation of bromate in the water body is very important when the ozone/activated carbon process is used for advanced treatment of drinking water.

Contents of the invention

The invention aims at the deficiencies of the prior art, and aims to provide a method for controlling bromate generation in an ozone/activated carbon advanced water treatment process.

To achieve the above object, the solution of the present invention is:

A method for controlling bromate generation in ozone/activated carbon advanced water treatment process, it may further comprise the steps:

Add available chlorine to the raw water body, and carry out the ozone/activated carbon advanced water treatment process after the bromide ion in the raw water body is converted into hypobromous acid.

Preferably, the dosage of available chlorine is less than 5mg/L.

Preferably, the pre-chlorination time of available chlorine is 1-180mim.

Preferably, the pre-chlorination time of available chlorine is 30-120min.

Preferably, the pH value of the raw water body is 5-9, the temperature is 0-40°C, and the oxygen consumption is 0.2-6.0mg/L.

Preferably, the concentration of ammonia nitrogen in the raw water is 0-3mg/L.

Preferably, the concentration of bromide ions in the raw water is 50-500 μg/L.

Preferably, the mass ratio of ozone input to available chlorine in the ozone/activated carbon advanced water treatment process is (1‐10):1.

Preferably, the mass ratio of ozone input to available chlorine in the ozone/activated carbon advanced water treatment process is (1.5-6):1.

Preferably, the concentration of ozone introduced into the ozone/activated carbon advanced water treatment process is 1.5-40mg/L, and the reaction time is 30-60min.

Owing to adopting said scheme, the beneficial effect of the present invention is:

First, before the bromate precursor is subjected to the ozone/activated carbon advanced water treatment process, available chlorine is added to react, so that the generation of bromate is well controlled, so that its concentration meets the "Drinking Water Hygienic Standard" (GB5749-2006) below 10μg/L.

Second, the reaction conditions of the present invention are simple, no special equipment is required, and there is no special temperature requirement, thereby making it widely applicable.

Third, the present invention is based on the existing water treatment process of the water plant, does not require large-scale technical transformation, and has high operability.

In a word, the method for controlling the generation of bromate in the ozone/activated carbon advanced water treatment process of the present invention overcomes the problems of poor economy and low treatment efficiency in the prior art, and has the characteristics of low cost, obvious control effect and simple operation. , so that it has a wide range of applications, and has achieved a certain degree of application in actual production.

detailed description

The invention provides a method for controlling bromate generation in an ozone/activated carbon advanced water treatment process.

A method for controlling bromate generation in ozone/activated carbon advanced water treatment process, it may further comprise the steps:

Before the bromide precursor bromide ions are oxidized by ozone, available chlorine is added to the raw water body, so that chlorine gas and the raw water body fully react to generate hypochlorous acid, and the hypochlorous acid converts the bromide precursor bromide ions into hypobromous acid, and then Introduce ozone into the raw water body for ozone/activated carbon advanced water treatment process.

In fact, the reaction rate of ozone with hypobromous acid (HBrO) is significantly lower than that with hypobromite (BrO ^- ), and hypobromous acid hinders the generation of hydroxyl radicals in water, thereby controlling Oxidation with hydroxyl radicals leads to the formation of bromate.

Wherein, the dosage of available chlorine can be less than 5mg/L, preferably 4mg/L.

The pre-chlorination time of available chlorine can be 1-180min, preferably 30-120min, more preferably 60min.

The pH value of the raw water body can be 5-9, preferably 8.15; the temperature can be 0-40°C, preferably 16°C; the oxygen consumption (COD _Mn ) can be 0.2-6.0mg/L, preferably 3.4mg/L ; The concentration of ammonia nitrogen in the raw water is 0‐3mg/L.

The concentration of bromide ions in the raw water can be 50-500 μg/L, preferably 110 μg/L.

The mass ratio of ozone input to available chlorine in the ozone/activated carbon advanced water treatment process can be (1‐10):1, preferably (1.5‐6):1.

The concentration of ozone introduced into the ozone/activated carbon advanced water treatment process can be 1.5-40mg/L, preferably 3mg/L; the reaction time can be 30-60min, preferably 30min.

The present invention will be further described below in conjunction with the shown embodiments.

Example 1:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample. The temperature of the raw water body was 16°C, the pH value was 8.15, the oxygen consumption was 3.4 mg/L, and the concentration of the bromate precursor bromide ion was 110 μg/L. Add 4mg/L of available chlorine in the water to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Among them, the dosage of available chlorine is less than 5mg/L, and the pre-chlorination time of available chlorine is within 1-180mim.

The pH value of the raw water is within 5-9, the temperature is within 0-40°C, and the oxygen consumption (COD _Mn ) is within 0.2-6.0mg/L.

The concentration of bromide ion is within 50-500μg/L.

In the above process, the concentration of ozone introduced is within 1.5-40mg/L, and the reaction time is within 30-60min.

Example 2:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample. The temperature of the raw water body was 16°C, the pH value was 8.15, the oxygen consumption was 3.7mg/L, and the concentration of the bromate precursor bromide ion was 110μg/L. Add 2mg/L of available chlorine to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Example 3:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample, wherein the temperature of the raw water body was 10°C, the pH value was 7.0, the oxygen consumption was 3.6 mg/L, and the bromide precursor bromide ion concentration was 155 μg/L. Add 1mg/L of available chlorine in the water to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Example 4:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample, wherein the temperature of the raw water body was 10°C, the pH value was 8.1, the oxygen consumption was 3.5 mg/L, and the concentration of the bromate precursor bromide ion was 142 μg/L. Add 1mg/L of available chlorine to carry out pre-chlorination reaction, the time is 120min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Example 5:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample, in which the temperature of the raw water body was 10°C, the pH value was 8.1, the oxygen consumption was 3.3 mg/L, and the bromide precursor bromide ion concentration was 200 μg/L. Add 1mg/L of available chlorine in the water to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Embodiment 6:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample. The temperature of the raw water body was 10°C, the pH value was 8.1, the oxygen consumption was 3.4 mg/L, and the concentration of the bromate precursor bromide ion was 200 μg/L. Add 2mg/L of available chlorine to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Embodiment 7:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample, in which the temperature of the raw water body was 16°C, the pH value was 8.15, the oxygen consumption was 3.6 mg/L, and the bromide precursor bromide ion concentration was 110 μg/L. Add 1mg/L of available chlorine in the water to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Embodiment 8:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample, wherein the temperature of the raw water body was 10°C, the pH value was 8.5, the oxygen consumption was 3.6 mg/L, and the concentration of the bromate precursor bromide ion was 155 μg/L. Add 1mg/L of available chlorine in the water to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Embodiment 9:

The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process of the present embodiment may further comprise the steps:

The raw water body of Taihu Lake was taken as a water sample. The temperature of the raw water body was 30°C, the pH value was 8.1, the oxygen consumption was 3.4 mg/L, and the concentration of the bromide precursor bromide ion was 155 μg/L. Add 1mg/L of available chlorine in the water to carry out pre-chlorination reaction, the time is 60min, then feed 3mg/L of ozone, after reacting for 30min, test the content of bromate in the water sample, the test results are shown in Table 1.

Table 1 The content of bromate when adding available chlorine and not adding available chlorine

As can be seen from Table 1, by adding available chlorine to react, the generation of bromate is greatly reduced compared with that without adding available chlorine, and the production efficiency of bromate is controlled as high as 90.37%, and with the addition of available chlorine content The increase of bromate is constantly decreasing, which shows that the present invention has the characteristics of low cost, obvious control effect and simple operation, so that it has a wide range of applications and has achieved a certain degree of application in actual production. .

The above description of the embodiments is for those of ordinary skill in the art to understand and use the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. a method for controlling bromate generation in an ozone/activated carbon advanced water treatment process is characterized in that: it may further comprise the steps: Add available chlorine to the raw water body, and carry out the ozone/activated carbon advanced water treatment process after the bromide ion in the raw water body is converted into hypobromous acid. 2. the method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, is characterized in that: the dosage of described available chlorine is less than 5mg/L. 3. the method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, is characterized in that: the prechlorination time of described available chlorine is 1-180mim. 4. the method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, is characterized in that: the prechlorination time of described available chlorine is 30-120min. 5. the method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, is characterized in that: the pH value of described raw water body is 5-9, and temperature is 0-40 ℃, and oxygen consumption The amount is 0.2-6.0mg/L. 6. The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, characterized in that: the concentration of ammonia nitrogen in the raw water body is 0-3mg/L. 7. The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, characterized in that: the concentration of bromide ions in the raw water body is 50-500 μg/L. 8. the method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, is characterized in that: the ozone feed rate in the described ozone/activated carbon advanced water treatment process is the same as that of the available chlorine The mass ratio is (1‐10):1. 9. the method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, is characterized in that: the ozone feed rate in the described ozone/activated carbon advanced water treatment process is the same as that of the available chlorine The mass ratio is (1.5‐6):1. 10. The method for controlling bromate generation in the ozone/activated carbon advanced water treatment process according to claim 1, characterized in that: the concentration of ozone introduced in the ozone/activated carbon advanced water treatment process is 1.5-40mg/L , the reaction time is 30‐60min.