Nitrogen Transformation In The Land Treatment Process Of Demestic Sewage

As a kind of innovation and replacing technology , land treatment has advantages:the cost of operation is low,the management is easy,the operation is simple,the handing effect is better and so on.In recent years,land treatment has been utilized extensively in the treatments of town wastewater,low COD concentration industrial wastewater, wastewater from farm and third stage treatments of some high density wastewater.Now the study about transformation way of contaminant in land treatment is few. The study adopted three kinds of packing:clay, clay with 15% husk of rice, clay with 30% husk of rice were used by author, to make the packing columns of different heights, through this way discussed the regular patters of nitrogen transformation and movement during the processes of the land trentment, The major conclusions are as follows.(1)To establish the transformation model of TN in the land treatment equipments through the rate model of NOx-N transformation in biological filter beds. The model is statistical remarkable and to described the transformation rates of TN in the experimential land treatments by the model, most of NH4+-N have been nitrified in the packing surface from 20cm to 30cm, the transformation model of NH4+-N is suitable dynamics model. The highest concentrations of NO3--N is at the 30cm sites of packing columns. Bio-reacting rate of NH4+-N accords with zero-order kinetics in the ordinary treatment devices. Compared with the ordinary treatment devices,the regular patter of the experiment shows: Transformation of NH4+-N has own oxidative mechanism and condition.(2)Through the change of method of finite difference analyize calculation of COD and TN in the research result of this experiment, suggest that SND may occur in the upper proportion of the experimental devices.(3) In the clay columns, from 40cm to 50cm section ,accoding to traditional nitrification and denitrification reaction,the changes of TN needed COD quantity that to estimate accoding to the traditional nitrification and denitrification reaction patters are more than that to obtain in the experiments, both oxygen concentration and carbon source are very low in the section, suggest that ANAMMOX reaction may occurred to be conculed, which maybe explained the transformation rate of NO3--N can not good use of the TN. Through the test ways of biochemistry next phase, the conjecture need walidate the existence of anaerobic-oxidation bacteria.(4) In land treatment,the transformation and transference of nitrogen are combination of several rections,COD is one of influence factors,and C/N is other,therefore the study concerned the transformation of COD in land treatment,the ex shows the rection is suitale a level dynamics model,the respond constant k2 is biger,the treating effect is better.C/N of thewastewater used in this study is low, the study had two ways:one is to fix COD and change NH4+-N,the other is to fix NH4+-N and change COD,the result shows:fix the COD density of into wastewater 300 mg/L, NH4+-N vary in range of 30～100 mg/L, NH4+-N density of out water is less than 9 mg/L; fix the NH4+-N density of into wastewater40 mg/L,COD vary in range of 180～420 mg/L, COD density of out water is more than 100 mg/L, and have exceed standard. The test show the handle effect of TN is the best when C/N is 8.(5) The clay as materials of the wastewaters land treatment divices may contain heavy metals such as manganese in this experiment. It may not be to meet the stantards of environmental mangement department of government. This paper reserched the methods to control the concentrations of manganese in the effluent of the divices. To compare that adding 5% lime and 15% rice husk with that adding nothing by leaching experiments with water, the results of experiments show the packing with lime had no manganese leached out within the period of 2 months, the concentrations of Mn always keep in the sphere of national environmental standard requirement. The concentrations of Mn in the efflences from the packing with clay or clay+rice husk were increasing linearly within one week, The concentrations of Mn after 21 days leached. In the effluents of short period manganese content exceed, in order to reach emission requirement,contact oxidize way to exclude is usually used.The results show, selecting soil as stuff,pay attention to the pollution of heavy mental,especially,in abnormity area.