Odor Release During Alkaline-saline Soil Improvement With Sewage Sludge

The sludge land use is effective to solve the problem of the municipal sewagesludge way out,also bring a lot ecological benefits for environment. But theenvironmental problems cannot be neglected during the process.This paper take theHarbin municipal sewage dewatered sludge and alkali soil of Duiqing village on thenorth side of Songhua river as test objects to investigate the best mixing rotio ofmunicipal sewage sludge and alkali soil and the release law of odor in the process, onthe basis of the test,we use AERMOD model in EIA Professional Assistant SystemSpecial for Air to imitate odor release law and analysis the effect on odor bymeteorological factors.The test results of best mixing ratio of municipal sewage sludge and alkali soilshowed that: additive ratio of sewage sludge was10%~50%could reduce soil bulkdensity and pH value obviously, additive ratio of sewage sludge was10%~70%couldincrease of soil organic matter obviously and made the soil total nitrogen, totalphosphorus and total potassium content increased3.87times,6.38times and43.09times respectively. The heavy metal content in sludge and alkali soil were probablyless than the urban sewage sludge disposal in muddy land improvement (CJT291-2008);When additive ratio of sewage sludge was10%~50%seed germinationrate would rise with the sludge dosing proportion increase,then the best mixing ratioof1:1was determined.Five kinds of odor were released during the process of dewatered sludgeimproving alkali soil they were ammonia, hydrogen sulfide, methanthiol, two methyldisulfide, two methyl three sulfur, The researching of the main contributor ammoniaand hydrogen sulphide diffusion rule showed that the concentration of the odor wentupwards according to the best mixing ratio in the1th hour.Specially, the concentrationof ammonia increased from9.88to16.70mg/m~3, and that of sulfide was from0.82to1.43mg/m~3. The concentration of those two typical odors showed a gradual decreasingafter the initial1h operation. The concentration of ammonia and hydrogen decreasedto0.35mg/m~3and0.24mg/m~3.Odor release rate was positively related with additiveratio and temperature; In the the process of sludge land use, the absence of odor washarmful to the health of human body in the initial period of time, but in24h, ammoniaand hydrogen sulphide can achieve level3standards of the urban sewage treatmentplant emissions standards (GB18918-2002), odor concentration was45, odorl indexwas17, odor strength reach to level3, odor had a effect on human body olfactorysenses; A week later, ammonia and hydrogen sulphide concentration were0.18mg/m~3and0.0076mg/m~3which could achieve the residential area of harmful substances inthe atmosphere the maximum allowed concentration (TJ36-79), odor index was5, then odor strength would be2below level and the human body senses for barely smellsmell reflect, it was not easy to identify it checks threshold.The results of simulation the process of sludge improving alkali soil byAERMOD was reach a basic agreement with the measurement results. the summerNH3and H2S presented the highest concentration in summer and the pollution ofdownwind direction was relatively serious by the leading wind summer forsouthwest.Instead,it presented lowest concentration in winter, the spring and autumnwere the same and spring was a little higher. The NH3concentration in the process ofdewatered sludge improving alkali soil was beyond level3standards of the urbansewage treatment plant emissions standards (GB18918-2002), however H2Sconcentration reach the level3standards to the urban wastewater treatment p lantemissions standards GB18918-2002. After six months period of compost the NH3and H2S both reached the residential area of harmful substances in the atmospherethe maximum allowed concentration (TJ36-79). The diffusionofodor and wind speedrate positively related but negatively related with atmospheric stability andatmospheric mixing height.