Model And Optimization Of Organic Pollutants Flow In Agricultural And Industrial Circular Production System Based On Reed-Planting For Papermaking

Sustainable development put forward the concept of circular economy, the realization of which was further demonstrated by the ecological engineering. Wastewater disposal and recycle ecological engineering is booming in China, but the study of modeling of compound system analysis is far from satisfaction. Therefore attempt was made to model from the whole wastewater disposal ecological engineering system. The branch model is of dynamic simulation, and it is preponderant in imitating the trend of organic pollutants accumulation in reed field. The whole compound ecosystem was analyzed according to the model operation established, and then the results were simulated and optimized, which can be the reference for papermaking mills to improve the production and wastewater disposal control. What is also significant is to spread reed and papermaking integrative system, and to popularize wetland circular economy.The followings are the results obtained in the present work:1. The mode of reed-planting-papermaking-sewage irrigation-reed-planting cycle is of benefit for the reed constructed wetlands ecosystem. Experiment and fieldwork found that the reed was in better condition when irrigated by wastewater from papermaking process, which increased about twenty percents of the yields. The purification of wastewater amounted to 82.3%, and sewage irrigation increased the amount of microbe in the soil, which make the environment in a good condition. In addition, reed wetland irrigated by wastewater showed no harm to the red -crowned crane's life. Although sewage irrigation brought about a light pollution to the groundwater, the deep groundwater was not affected. The water quality of surface water adjacent to reed field was stable, and seawater quality kept being at a highstandard as in level I.2. Based on the result of experiment and fieldwork, the model of organic pollutants flow in agricultural and industrial circular production system by reed-planting for paper-making was established. The model operation result showed that the compound system was stable and had its equipoise point, which indicated the structure of the reed and papermaking compound system was reasonable. Perturbation analysis and parameter sensitive analysis to the compound system revealed that parameters f23 and f64 were significant to the whole organic pollutants circular flow and might be the governing parameters.3. The model was applied to the case of Sund and was optimized. Optimized simulation found the principles of organic pollutants accumulation in the reed field branch. In the first year, the organic pollutants accumulation velocity was high, which might be caused by the adaptability of reed wetland to the pollutants in wastewater from papermaking. The accumulation velocity trend line dropped suddenly from the second year to the fifth year, which showed that the wetland ecosystem was well-grown, and that the decontaminate ability was improved. Then after two obvious fluctuations, the accumulation velocity trend line tends to be stable, and the equipoise point is at the 31st year.4. According to the result of optimized simulation and analysis, organic pollutants flow governing countermeasures are given as follows: when the system structure is reasonable, governing parameters should be called for to reduce the amount of organic pollutants in wastewater emission from pulp process, and the concentration control before entering the reed field is important; when the model cannot find the system equipoise point, the system structure should be adjusted.