abstract

The pilot study of advanced treatment of Huangpu River raw water by O32BAC process shows that O32BAC can keep the removal of organic matter in water for a long time, and the average removal rate of CODMn is 27 15%. The average removal rate of TOC is 3417%; The average removal rate of UV254 is 57%. The process can also remove manganese and chromaticity from water, and convert water with positive Ames test into water with negative Ames test.

Pilot test of ozone biological activated carbon; Polluted raw water

Because a large amount of industrial wastewater and domestic sewage can be diverted from the upper reaches of Huangpu River without proper treatment, the raw water is taken from the lower reaches of Huangpu River and discharged into the water body nearby, causing serious pollution of drinking water sources in many places, threatening the influence of wastewater pollution from nearby large iron and steel plants, and the quality of raw water is poor. Hygiene and safety of water. Facing the serious water pollution problem, Shanghai factory is equipped with ozone generating equipment to cope with the polluted raw water quality. On the one hand, the city invested heavily in the construction of the upper reaches of Huangpu River diversion project; Find another way. See figure 1 for the water purification process of Zhoujiadu Waterworks. On the one hand, it is also exploring the technological process of strengthening the treatment of polluted raw water. In the early 1980 s, the former Shanghai water supply company also carried out a small test of O32BAC process [1 ~ 2] Based on small-scale experiments, this paper studies the feasibility of advanced treatment of polluted raw water in the lower reaches of Huangpu River by O32BAC process. The experiment was completed in Shanghai Zhoujiadu Waterworks, with the number 1996.

1 Test conditions and equipment11/overview of Zhoujiadu Waterworks. Zhoujiadu Waterworks is located on the Huangpu River in Zhoujiadu District, Pudong, Shanghai, with a treatment capacity of about 20,000 m3/d.

Table 2 Comparison of coagulant use effect and benefit

Coagulant cost

After 20 minutes of precipitation,

Optimum dosage of coagulant

Clarifying layer turbidity /NTU

/yuan/cubic meter

2215mg/l PAC

2 1 103

0 10 18 0

12 10 mg/l PFS

10 120

0 1004 2

1 mg/l PAC+0 1 1 mg/l PAM-A

1 150

0 1002 0

1 mg/l PFS+0 1 1 mg/l PAM-A

1 120

0 100 1 6

Note: PFS 350 yuan/ton, PAC 800 yuan/ton, PAM-a 12000 Yuan/ton.

PAM -A, or the combination of PFS and PAM-A, can rapidly reduce the turbidity of Xijiang River from hundreds of N TU to less than 2N TU in a short time, and the cost is only about 65,438+00% of the cost of adding PAC alone in water plants (the amount of adding PAC alone in water plants is often 65,438+02 ~ 25 mg/L). In addition, by using the compound addition method of coagulant, floc precipitation is rapid and can be reduced.

3 Conclusion

For the coagulation and sedimentation of Xijiang River, the effect of adding polymeric iron and anionic polyacrylamide is better than adding polymeric aluminum and anionic polyacrylamide. However, the coagulation and sedimentation speed of the two composite dosing methods is several times faster than that of the single use of polyaluminum and polyiron, and the treatment cost is 50% ~ 92% lower than that of the original method. By improving the dosing method of coagulant, the content of aluminum salt and polyacrylamide monomer in water can be reduced, thus reducing the harm to human health.

The inlet water is directly lifted to the ozone contact chamber of this test by pipeline pump. The ozone contact room is! 400,4m high stainless steel tube, ozone contact time is 765438±05min, and the effluent from ozone contact chamber enters the activated carbon column. Activated carbon column is! 800 stainless steel cylinder, height 3 15m, made of Taiyuan ZJ-15 granular activated carbon, filling height 2m, empty column filtration rate 8 ~ 9m/h, EBCT 13 ~ 15min. The test flow is shown in Figure 2.

Fig. 2 O32BAC process test flow

2 test results

The experiment is mainly divided into two stages, one is activated carbon adsorption stage, the other is O32BAC process stage. During the experiment, the activated carbon in the activated carbon pool has not been replaced. The division of the two stages mainly depends on whether ozone is added or not and the breakthrough of activated carbon adsorption. In the later stage of activated carbon adsorption, from the perspective of NH3-N degradation, there are microbial activities in the carbon layer, but the dissolved oxygen in the filtered water is only about 2mg/ L, so it is estimated that the influence of microorganisms is not obvious. 2 1 1 activated carbon adsorption stage

1March 2, 9961day activated carbon column was put into adsorption operation without ozone. In order to improve the coagulation effect, a small amount of chlorine gas was added at the entrance of the conventional reaction tank in the water plant. After reaction 2 precipitation 2 filtration, there is no residual chlorine in the water entering O32BAC process. At this stage, the influent and effluent chromaticity, CODMn, UV254 and NH3-N of the activated carbon column are mainly monitored, and the breakthrough point of the activated carbon column and the growth of microorganisms in the column are judged according to the measured data. The change curves of CODMn, UV254 and NH3-N at this stage are shown in Figure 3 ~ Figure 5 respectively.

As can be seen from Figure 3 and Figure 4, the removal rate of CODMn and UV254 by activated carbon is very high at the initial stage of adsorption, and with the gradual saturation of adsorption sites, the removal rate has an obvious decline process, and finally stabilizes in a lower value range. The end point of the descent process is within 35 ~ 40 days after operation. It can be seen from the ammonia nitrogen curve that the activated carbon column began to remove ammonia nitrogen from the water after 30 days of operation, indicating that there were microorganisms in the carbon layer.

Fig. 5 NH3-N activity curve in activated carbon adsorption stage. When the water temperature is low in March and April, it takes about a month for the activated carbon column to form a film naturally. Judging from the above curve, the adsorption of activated carbon column reached saturation after 40 days of continuous operation. 2 12 O32BAC stage

Ozone began to be added on June 3, and entered the O32BAC stage. The dosage of O3 is mainly between 2 10 ~ 3 10 mg/L, and the actual absorption is between115 ~ 210mg/L. During the experiment, in order to investigate the influence of O3 dosage, it will be added in a short time. The experiment also

It was found that with the increase of O3 dosage, the absorption rate gradually decreased from nearly 80% to slightly higher than 50%.

This stage lasted for more than three months from the beginning of June to the end of September, during which various data were analyzed. Daily analysis includes turbidity, chromaticity, pH value, CODMn, UV254, TOC, NH3-N, NO 2-N, NO 3-N and Mn. 2 12 1 1 routine analysis and statistical results

See table 1 for the statistical results of routine analysis.

Table 1 Statistical Table of Conventional Water Quality Analysis Data

Name of indicator Name of water sample Statistical days/day Maximum and minimum average removal rates of filtration level and ozone level

Turbidity /N TU filtered water O3 is carbonated water 2323231604172019060124401477010900/660.

The chroma/chroma filtered water O3 is 31313116281501313.

CODMn/mg/ L filtered water O3 is 31313161kloc-0/75145418631663. 3 167 12 1 1 % 27 15 % 17 15 %

UV254/1/ Cm filtered water O3 effluent charcoal effluent 25 25 25 0157 010501079 010820103/kloc. 5438+0075 0 1049 34 12 % 57 % 34 17 %

The water O3 after TOC/mg/ L filtration is 28 28 717 716617 21921135195.

NH3 -N/mg/ L O3 in filtered water is 3131316143615451501891. +0 130 - 12 17 % 48 14 % 54 12 %

Mn/mg/ L filtered water O3 is carbonated water 2828280130013001001201160.

It can be seen from the statistical results in table 1 that the average removal rates of turbidity, chromaticity, CODMn, VU254, TOC, NH3-N and Mn in the filtered water are 3 1 18%, 47 14% and 27/kl, respectively. This result is consistent with the small-scale test result of O32BAC process in this factory [1]. The average removal rate of CODMn in O32BAC stage is relatively low. The reason may be that the influent ammonia nitrogen concentration is high, and the nitrification reaction in the activated carbon pool consumes too much dissolved oxygen, which affects the effect of biodegradation and removal of organic matter in the activated carbon pool. See Table 2 for the statistical average value of dissolved oxygen detection at the upper, middle and lower positions of the activated carbon tank.

20 water supply and drainage, vol. 126,No. 1 12, 2000

Table 2 Changes of statistical average value of dissolved oxygen concentration at different carbon layer heights

Statistics high dissolved oxygen/mg/L medium dissolved oxygen/mg/L low dissolved oxygen/mg/L.

22 9 109 2 126 0 129

Removal effect of 2 12 12 O32BAC process on organic matter 212121organic comprehensive index.

In the study of water treatment, permanganate index (CODMn), ultraviolet extinction value (UV254) and total organic carbon (TOC) are commonly used to represent the comprehensive indicators of organic matter in water. During the research, all three indicators were monitored, and the results are shown in Figure 6 ~ Figure 8 respectively.

As can be seen from Figure 6 to Figure 8, the removal rate of UV254 is the highest and most stable among the three indicators. It is generally believed that UV254 represents an organic compound containing unsaturated double bonds and benzene rings, which has a strong absorption of ultraviolet light. Due to the strong oxidation of ozone, the unsaturated double bond can be broken and the benzene ring can be opened, which makes UV254 decrease rapidly. The removal of CODMn and TOC is interfered by many factors. In addition to ozone oxidation, activated carbon adsorption and microbial degradation are also very important, so the removal rate is slightly lower and fluctuates greatly. 2 12 12 12 to remove chloroform, carbon tetrachloride, total organic halides and polycyclic aromatic hydrocarbons.

After the activated carbon adsorption stage and O32BAC process mature, two samples were taken to analyze the removal effect of organic matter. The results are shown in Table 3.

As can be seen from Table 3, activated carbon adsorption has a good removal effect on various organic substances. O32BAC process also has good removal effect on TOX, phenanthrene, anthracene and fluoranthene. After O32BAC treatment, CHCl3 and CCl4 not only did not decrease, but increased slightly. The reason may be that once CHCl3 and CCl4 are formed, O32BAC cannot be decomposed and can only be removed by activated carbon adsorption. When the activated carbon is saturated, if the influent CHCl3 and CCl4 are low, CHCl3 and CCl4 on the activated carbon will precipitate, resulting in a slight increase in effluent CHCl3 and CCl4. 2 12 13 to remove chroma and manganese

During the test, the chromaticity and manganese in the inlet and outlet water of O32BAC process were also monitored for a long time. Because Zhoujiadu Waterworks is located near the iron and steel plant, the chromaticity and manganese content of raw water are high, and the chromaticity and manganese content of factory water often exceed the standard. After O32BAC treatment, the chromaticity and manganese are greatly reduced, and the effluent quality is greatly improved. The curves of chromaticity and manganese are shown in Figure 9 and Figure 10. 2 12 14 Ames test

Samples collected on September 2nd 1996 were entrusted to the Environmental Health Department of Shanghai Medical University for Ames test. The water samples collected are raw water, filtered water, factory water and effluent from activated carbon column. The difference between factory water and filtered water is that factory water is filtered water, which is chlorinated by 1 15mg/L and stays in Qingshui Reservoir for 30 ~ 40 min, and is taken from the factory-specific factory water sample faucet. The effluent of activated carbon column is the filtered effluent after O32BAC process. Two strains TA 100 (base substitution mutation) and TA98 (frameshift mutation) were selected for Ames test. Results Ames test was not detected in all water samples of TA 100 strain.

Table 3 Some organic indicators

Name of water sample test date: chcl3/μ g/lcl4/μ g/ltox/μ g/l; Naphthphenanthrene anthracene pyrene, pyrobenzo (b) pyroanthracene benzo (k) pyroanthracene benzo (a) pyrene benzo (ghi) pyrene indeno (1, 2,32 cd).

0320 raw water filtration carbonized water 71171701212501610. 6 10 18 12 17 17 & lt； 1 10 12 1 13 0 18 1 16 5438+09 1 1 1 1 1 1 19 & lt； 1 10 14 13 10 12 & lt； 1 10 & lt； 1 15 & lt； 1 15 & lt； 1 15 & lt； 2 10 & lt； 2 10 & lt； 2 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 2 15 & lt； 2 15 & lt； 2 15 9 12 & lt； 5 10 & lt； 5 10

07 15 raw water filtered water O3 effluent carbonated water1111641201230/kloc. 2 148 19 48 10 30 16 554 & lt； 6 10 & lt； 6 10 & lt； 6 10 100 63 12 59 12 5 16 5438+05 5 12 2 18 16 5438+09 19 13 18 18 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 15 & lt； 1 15 & lt； 1 15 & lt； 1 15 & lt； 2 10 & lt； 2 10 & lt； 2 10 & lt； 2 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 1 10 & lt； 2 15 & lt； 2 15 & lt； 2 15 & lt； 2 15 & lt； 5 10 & lt； 5 10 & lt； 5 10 & lt； 5 10

Note: Unless otherwise specified, all data in the table are in nanograms per liter.

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Fig. 1 1 TA98 strain (+S9) Ames test results

Figure 12 TA98 strain (-S9) showed positive Ames test results. The detection results of TA98 strain are shown in figure 1 1 and figure 12.

As can be seen from Figures 1 1 and 12, the raw water of Zhoujiadu Waterworks has frameshift mutation, and the mutagenicity of the effluent after conventional treatment is enhanced, and the direct mutagenicity (-S9) of all water samples is stronger than the indirect mutagenicity (+S9). After the filtered water is treated by O32BAC process, it changes from mutagenic positive to mutagenic negative, which is obviously very beneficial to protect people's health. The results of Ames test in this experiment are basically consistent with the results of small-scale test [1], which shows that the conclusion that O32BAC process changes the Ames test properties of Huangpu River water is not accidental and repeatable. Removal of 2 12 15 ammonia nitrogen

O32BAC process has certain ability to remove ammonia nitrogen. See Figure 13 for the ammonia nitrogen removal effect in this experiment.

It is found that the ability of O32BAC process to remove ammonia nitrogen is limited due to the lack of dissolved oxygen. When the influent ammonia nitrogen concentration is high, the ammonia nitrogen removal rate is low, the oxidation is incomplete, and the effluent nitrite nitrogen concentration is increased, which affects the removal effect of organic matter. When the influent ammonia nitrogen concentration is low, the removal rate is high and oxidation is complete. Therefore, it is suggested that the influent ammonia nitrogen concentration of O32 biological activated carbon process should be controlled below 2 mg/L.

The study of (1) shows that the O32BAC advanced treatment process is effective.

22 Water Supply and Drainage VolumeNo. 126No. 1 12, 2000

Removal of organic matter from raw water of huangpu river. The experimental device has been running for more than half a year, and the activated carbon has not been replaced and regenerated, and the removal rate of CODMn is maintained at 20% ~ 40%. TOC removal rate is 20% ~ 45%; The removal rate of UV254 is 40% ~ 70%. The analysis of specific organic compounds shows that the process can partially remove polycyclic aromatic hydrocarbons and TOX from water, but it can not decompose and remove the formed CHCl3 and CCl4, and can only be removed by activated carbon adsorption. When the adsorption is saturated, the process has no ability to remove CHCl3 and CCl4.

1 (2) O32BAC process has a good removal effect on chroma and Mn in water. In the experiment, the average chromaticity decreased from 13 13 degrees to 7 degrees. When the influent Mn exceeds the standard, the removal rate is between 70% ~ 100%, and the qualified rate of effluent Mn reaches 100%.

2 (3) O32BAC process can transform Huangpu River water with positive Ames test into negative Ames test, thus improving the quality and safety of drinking water and protecting people's health.

3 (4) O32BAC process has a certain ability to remove ammonia nitrogen, but the concentration of ammonia nitrogen in influent should be controlled below 2 mg/L. ..

4 (5) O32BAC process is suitable for advanced treatment of raw water polluted by Huangpu River.

refer to

1 LV xiwu. Study on water purification technology of biological activated carbon: [dissertation]. Shanghai: Tongji University, 1987.

2 Lu Zaihong. Removal of organic matter from water by ozone -2 biological activated carbon process. Shanghai environmental science,1986,5 (3): 2 ~ 4