Study On The Treatment Of Black And Odorous Water Body Based On Agricultural Waste

Water resource is an indispensable part for human survival,but with phenomenonof stealing,leaking,and people's weak consciousness of water pollution,black and smelly water bodies appear frequently,especially in cities.Urban water body,an important part of urban system,is urgently to be repaired.The treatment and restoration technology of black and odorous water includes physical method,chemical method,biological method and comprehensive method.Nowadays,the utilization of agricultural wastes is considered more common because straw,fruit shell and leaves are inexpensive and convenient,besides that they also enjoy great utilization potentiality.This project is based on the method of agricultural waste,aiming to control the black and odorous water body in the city.In this paper,the flocculant is prepared through the modification of corncob,and thus obtain the best experimental conditions:when the NaOH concentration is 20%,the swelling temperature is 20?,and the dosage of CS₂ was 1.5 ml,corncob xanthate holds the best removal effect on ammonia nitrogen,COD and simulated Cu²⁺waste water.At the same time,when the dosage of corn cob modified flocculant is 0.7 mg/L,it enjoys the best removal effect on ammonia nitrogen,COD and simulated Cu²⁺waste water.When the pH value of black smelly water is 7,corn cob modified flocculant has the best treatment effect on ammonia nitrogen and cod.For simulated Cu²⁺waste water,when the pH of waste water is between 7 and 9,the flocculation and adsorption effect improve.The charcoal,gained by straw,is aimed to absorb the heavy mental in river sediment.With the increase of time,the quality of biochar and the initial concentration,the removal rate of Pb²⁺,Hg²⁺,Cr⁶⁺increased gradually.After reaching a certain value,when the adsorption time is 48 h,240 min and 48 h,the dosage of biochar was 0.5 g,5.0 mg and 0.7 g respectively,the adsorption rate reached the maximum value.When the initial concentration of lead ion is 20 mg/L,the adsorption efficiency is the highest,reaching 87.52%,with the absorbing capacity of 1.7503 mg/g.When the initial concentration of mercury ion is 240?g/L,the efficiency reaches the highest,reaching 87.83%,with the capacity of 2.1079 mg/g.When the initial concentration of chromium ions is 2.4 mg/L,the adsorption efficiency is the highest,reaching 86.01%,with the absorbing capacity of 0.0412 mg/g.With the increase of pH value,adsorption time,activated carbon and adsorption temperature,the removal rate of heavy metals will be improved.After reaching a certain value,it remains steady,reaching the maximum adsorption rate when the pH is 6 and temperature is 25?.For the adsorption kinetics and thermodynamics,the research shows that at the adsorption of Pb²⁺,Hg²⁺,Cr⁶⁺follows the second-order kinetic model,and the adsorption conforms to Freundlich adsorption isotherm and Langmuir isotherm.Finally,through the experiment of agricultural waste and earthworm engineering bed,it shows that the straw biochar mixed filler is conducive to the reduction of ammonia nitrogen and COD in the black and odorous water.The average reduction rate of characteristic pollutants in the straw biochar mixed filler bioengineering bed is COD 37.65%and ammonia nitrogen is 90.46%.After adding earthworm,the straw biochar mixed filler bioengineering bed is beneficial to the black and odorous water body.The average reduction rates of the characteristic pollutants were COD 71.90%,ammonia nitrogen91.31%,COD 34.25%and ammonia nitrogen 0.85%.When earthworm was added to the bio engineering bed,the removal rate of ammonia nitrogen and COD in the black and odorous water of the city improved obviously,and the pH value of the effluent increased markedly.