Release Characteristics Of Odors During Sewage Sludge Stabilization

During the treatment and disposal process of sludge,there are different kinds of odor gases released.There is not many studies about odours from sludge.Adding lime is a widely used measure in sludge stabilization.But it could release a lot of ammonia.In order to control pollution,we need to know about the mechanism and release characteristics.This paper takes ammonia from city sewage treatment plant sludge as object.The result showes temperature is a very important factor.In the same temperature condition,when ratio of lime was 5%,the release amount of ammonia of 70? was 1.5 times of 50?,and 2.6 times of 30 ?.The higher temperature was,the more ammonia released.The overall trend of ammonia release curve at 30? was low.About 50? and 70?,the process could be divided into two stages.Firstly,ammonia generated in strong alkaline conditions at the beginning of lime added.When water content of sludge decreased to a certain level,the particles gradually exposed in the air.Ammonia adsorbed in pore started to volatilize.Secondly,complex molecules took part in the reaction with consumption of readily available nitrogen in sludge.Ammonia curve showed a trend of slow decline finally smooth.In general,the amount of lime exerted obvious effect on the sludge ammonia emission,the more lime added,the more ammonia released.Moreover,the promotion was observed to be correlated with temperature elevation.The influence of temperature on sludge ammonia release was stronger than lime.Besides,potassium propionate is a very good stabilizer in sludge odours releasing.Based on the mechanism of release of hydrogen sulfide as theoretical basis,we surveyed the different of hydrogen sulfide volatilization between air and nitrogen environment after adding potassium propionate into sludge.Moreover,we analyzed the mechanism and effectiveness of propionic acid potassium inhibition sludge decay.The result indicated that the amount of potassium propionate exerted obvious effect on the sludge and hydrogen sulfide emission,the more potassium propionate added,the less hydrogen sulfide released.Moreover,the inhibition was observed to be prominent with the increasing of pH value as well as the extension of time.In addition,the effect of sludge stabilization was better in nitrogen environment.2.5% potassium propionate in nitrogen could reach the efficiency of 3% in air condition.The inhibition mechanism of potassium propionate on hydrogen sulfide can be divided into two parts.Firstly,potassium propionate maintains the water content of sludge,so that free hydrogen sulfide is adsorpted in sludge pores.Secondly,potassium propionate inhibits bacteria producing hydrogen sulfide.