Study On The Effect Of Hydrothermal Method Combined With Bamboo Powder On Dewatering Performance Of Sewage Sludge

With the improvement of people’s quality of life and awareness of environmental protection,municipal wastewater treatment results in generating huge amount of sewage sludge,which has a bad effect on the environment.It requires economically and environmentally acceptable management before final disposal.On the one hand,it is difficult for Sludge dewatering because of the large amount of sludge and high moisture content.Generally.there is still has a moisture content of 80%in sewage sludge after mechanical dewatering.On the other hand,the composition of the sludge is complex because of containing a large amount of toxic and harmful substances.Therefore,sludge dewatering treatment is especially important for dewatering under low energy consumption and achieving resource-based final disposal.Three hydrothermal pretreatment methods were applied to this experiment.The dehydration performance of the sludge was improved by low temperature oxidation hydrolysis,thermal hydrolysis alone and alkaline thermal hydrolysis.Oxidant type,temperature,time,and alkali dosage are the process influencing factors.The mixed sludge with low moisture content and high calorific value is mixed with different amounts of bamboo powder to filter,it is defined as sludge solid fuel.It can achieve the effect of sludge hydrothermal carbonization after the natural air drying.Then further analyze its value as a fuel.Finally,using TG analysis the combustion characteristics of the mixed fuel,and calculate the energy consumption difference between the entire process and the traditional thermal drying method.The experimental results of different hydrothermal methods show that the method of low temperature oxidation of sludge using hydrogen peroxide and potassium persulfate needs to be improved.The optimum moisture content of hydrogen peroxide is 65.89%and 68.39%of potassium persulfate oxidation.According to the filtrate volume at 5 minutes,the sludge filtration performance is obviously improved by separate thermal hydrolysis and alkaline thermal hydrolysis,this leads to improved dewatering capacity.The water content change curve has the same trend which shows that moisture content decreases with increasing temperature and the moisture content first decreases and then changes slightly with time.The moisture content decreases first and then increases with the increase of the dosage in the alkaline hydrolysis experiment.The moisture content of the sludge filtered by suction can be reduced to 57.21%.After being treated for 90 minutes by adding 0.12 g of Ca（OH）₂ at 140°C.It achieves a similar suction filtration moisture content with a separate treatment at 180°C for 90 min.It is known from scanning electron microscope and infrared spectrum that proteins,polysaccharides,lipids and other substances are hydrolyzed into small molecules,the particles become smaller and the surface of the particles is broken during the hydrolysis of sludge.As a result,cells are destroyed and more bound water is released to improve sludge dewatering performance.A certain amount of bamboo powder can improve the filtration performance of sludge was obtained in the experiment.It can be known from the comparison of the moisture content calculated by mixing the sludge with bamboo powder alone.It further reduces the moisture content of the sludge while increasing the organic matter of the sludge and providing energy for the fuel.Moreover,the sludge combined with the bamboo powder is easily dried naturally and fully equipped with the value of fuel production.