Study On Microwave Modified Bentonite For Phosphorus Removal From Wastewater

With the growing of the production of industry and agriculture, the great growing ofpopulation, the abundant usage to the detergent which containing phosphorus, the use ofpesticide veterinary drug and chemical fertilizer, the phosphorus in the water is growinggreatly day after day. At present the urban wastewater treatment usually use sludge process, sothe water is also contain many phosphorus. And the chemical flocculation is a good methodbut it is expensive, so the use of chemical flocculation is being limited.Bentonite is a kind of clay mineral that is abundant in our country. It has uniquesandwich structure and powerful adsorption ability. Modification to the bentonite can enhanceits adsorption ability greatly and so makes it adsorb the contaminants such as heavy metalions and organic substances in wastewater more effectively, and it also can absorb phosphorusand so on. Microwave modified can enhance the absorption of the bentonite. The experimentresulted in three modified methods under the best preparation conditions. Microwaveactivated bentonite;the mixed bentonite with FeSO4 and the immersed bentonite.The facts affect the modified bentonite are the power of microwave, the time of heating,the quantity of FeSO4. The most important is the power of microwave, the experimentshowed that 480W is the most;when the time is 6min the removal ration is reach 90.0%, andin the 8min the removal ration is good, is 94.8% and 95.9%;the quantity of FeSO4 is alsoaffect distinctly, followed the grow of the quantity the removal ration is also grow. At 50mgthe solid modified bentonite is 82.0%, the liquid modified bentonite is reach 88.2% at only30mg.The facts affect the removal ration are stiring time, stiring speed, the initial phosphorusconcentration and the PH. At 5min, 180r/min, the removal ratio is higher than 90.0%;the PHis another fact that can affect the removal ratio greatly. PH between 6 and 8, the ration is morethan 80.0%;the initial phosphorus concentration grow the ration is drop gradually, but whenthe initial phosphorus concentration below 15mg/L, the ratio is also more than 70.0%.Experiment showed that throw 3g modified bentonite into 10mg/L wastewater theefficiency of removal ration is from 8.9% to 12.4%;and the bentonite append FeSO4 theefficiency are 90.9% and 93.4%. So the modified bentonite is good for the lower initialphosphorus concentration.