Optimization Research On Treatment Of Landfill Leachate Combination Of Diatomite, Zeolite And Activated Carbon

With the rapid development of economy, the consumption of resources is increasingly growing. Consequently, garbage problems are increasingly prominent, especially household garbage problem in the city. In China, the urban household garbage production is huge, and the bio-safety disposal degree is low, which lead to the dilemma that many cities have been surrounded by garbage. At present, sanitary landfill is the main method of disposing garbage in China, but this method will generate landfill leachate of higher levels of pollutants, and the water quality is complex, which have these characteristics of high COD concentration, high metal ions and high ammonia nitrogen content. This kind of waste water belongs to one of the hard-to-dispose waste water, and improper handling of it will harm the environment. In the last dozen years, scholars, at home and abroad, have been doing a lot of exploration on leachate treatment and think the filtration adsorption process within physio-chemical treatment methods is a pre-processing method, which has the characteristics of low cost and better removal efficiency of metal ions and refractory organics. Filtration adsorbent is the key in the filtration adsorption method. Finding a cheap and efficient filtration adsorbent becomes a current problem for environmentalist.In this study, we adopt the organic combination of diatomite, zeolite, and activated carbon to develop a new and efficient material or way of filtration, aiming to take full advantages of these materials, and improve the treatment effect. Adopting the method of orthogonal experiment, we optimize an appropriate proportion of diatomite, zeolite, and activated carbon. Using physical and chemical methods, we recycle and modify the filtered and abandoned filter material, which make it, to some extent, resume filtering performance and eliminate the fear of troubles from behind.This is a new method.In this study, we regard diatomite, artificial zeolite and activated carbon as filtration adsorbents. By mixing and layering the three kinds of filter material, we conduct filtration adsorption experiments on leachate. The results prove that diatomite has certain removal efficiency on each indicator, but it has better permeability and helps the process of filtration; artificial zeolite has better removal efficiency on ammonia nitrogen and COD, activated carbon has prominent removal efficiency on metal ions, turbidity and COD, but both of which have poor permeability. Mixing and layering process give full play to the advantages of the three kinds of filter material and various kinds of indicators have better comprehensive removal efficiency. In mixing process, removal rate of ammonia nitrogen metal ions, turbidity and COD respectively are 63.3%、81%、95%、50%; comparing to zeolite and activated carbon, the permeability improve substantially. In layering process, removal rate of ammonia nitrogen metal ions, turbidity and COD respectively are 88.8%、95%、100%、76.9%, but the filtration rate is greatly influenced by zeolite and activated carbon.In this study, through optimal experiments, we learn that when the leachate is over 180 ml, the proportion of activated carbon should be relatively low, and the proportion of zeolite should be relatively high; when the leachate is over 360 ml, the amount of diatomite in the filter material should be relatively small, and the proportion of activated carbon and zeolite should be equal. According to orthogonal range analysis, when filtering the capacity of 180 ml and 360 ml, activated carbon and zeolite have greater removal impact on pollutants, and diatomite have smaller removal impact on pollutants; among them, zeolite have the biggest impact on ammonia nitrogen, and activated carbon have bigger removal impact on COD and metal ions.In this study, through modifying and recycling experiments, in terms of COD, the ultrasonic recovery process have the best desorption effect; mixing and pickling recycle process have better removal effect on recycled filter material. Ultrasonic pickling and ultrasonic alkali cleaning processes can wash out lots of ammonia nitrogen from abandoned filter material; what’s more, the abandoned filter material which undergoes the ultrasonic alkali cleaning process helps to recover the removal rate of ammonia nitrogen to 89.5%, far more than the removal ability of new filter material; namely, for ammonia nitrogen, the ultrasonic alkali cleaning process is a good recycle method. Although ultrasonic pickling desorbs a small quantity of metal ions, recycled filter material have better removal ability on metal ions than new filter material; namely ultrasonic pickling is a better process of recycling. Ultrasonic pickling and ultrasonic alkali cleaning processes can wash out lots of turbidity. The recycled filter material which undergoes the ultrasonic pickling process have the best recovery effect on turbidity-removing process, exceeding the removal ability of new filter material; ultrasonic alkali cleaning process have the worst effect, and other modifying and recycling processes are all better. Based on the above comparison, ultrasonic pickling is the better process of recycling.