Advanced Treatment Research Of Wastewater In Nylon Production

The water all over the world is polluted badly at the present time. It is reported that about 400,000,000,000 ton polluted water is drained to rivers or lakers, which occupies around 21.4% in total flux in the world. The seven great water systems, including the Yangtze River and the Yellow river, are polluted in different extent, and most lakes, such as Taihu Lake, are in eutrophic state. Go with the rapid development of economy and improvement standard of people's living, the total flux is growing year after year, that makes the pollution of surface water resource worse directly. If the wastewater can be treated to the cleaner water which arrives at the environmental tolerance limitl, it will add water source which is propitious to slove the promblem of water shortage, and it has effect on treating pollution, too. So, the reuse of sewage is an effective way to save and utilize water source rational. At the same time, it is also an important aspect of preventing water polluting and boosting human curecontinuable development, that has crucial practical significance.In the dissertation, Biological Aerated Filter(BAF) process is used to advanced treat wastewater in nylon production, and it cleans the wastewater to satisfy the water quality criteria for discharge. Biological Aerated Filter runs to a new method to treat the sewage inland and outland these years. It has merits such as smaller cubage and bulk, higher quality discharged water, more simple treatment process, cheaper expense of capital construction and operation, more convenient management, and it can run fitful etc. When the process is in the different condition, the removal ratios of the pollutants, such as COD_cr, NH₃-N and TN, is also diverse. Study is made on it, and the best parameter for run is determinated. It provides theory for the process design, run, management in the furture, and it also offers a new thinking when a wastewater plant treats this sewage.The thing which is demonstrated by the experiment as follows: 1. The gas-water ratio has an effect on the efficiency when the process treats the sewage. With a small gas-water ratio, the process can gain a high efficiency. When the gas-water ratio is 2:1, the average removal ratios of COD_cr, NH₃-N and TN reaches 48.30%, 84.24% and 42.18%. 2. The hydraulic loading is also an improtant aspect when the prcocess runs. The removal ratios of the pollutants is decreasing with the hydraulic loading increasing. When the hydraulic loading is 0.39m³Â·m^-2·h^-1, the average removal ratios of COD_cr, NH₃-N and TN arrives at 48.53%, 84.81% and 42.55%. 3. Alongside the depth of filter bed, the removal characteristics of pollutants differ each other. The main region of COD_Cr removal is between the distance from water inlet to 60cm, and the removal ratios is 40.22%, which occupies about 83.27% in total removal ratios. The main region of NH₃-N removal between the distance from 20cm to 80cm, and the removal ratios is 81.33%, which occupies about 95.85% in total removal ratios. The main region of TN removal is between the distance from 20cm to 80cm, and the removal ratios is 39.63%, which occupies about 91.67% in total removal ratios. 4. The backwashing way which is gas combined with water is quite effective. The backwashing has a converse effect on remove of the pollutants, but it will reach the normal level when it re-run.After the wastewater which is in nylon production is advanced treated by the Biological Aerated Filter process, the concentration of COD_cr, NH₃-N and TN descends largely. The pollutants in the sewage is below the national water criteria for discharge. When the wastewater is discharged into the environment, it won't do badly harm.