Study On Anaerobic Digestion Of Primary Sludge And Desulfuration

Anaerobic digestion is a conventional sludge stabilized method for treatingsewage sludge as this method can reduce organics, kill pathogens, stabilize sludge andproduce biogas. The sulfide generated during the reaction would restrain the digestionprocess and reduce the effective use of biogas. In this study, the primary sludge wasdigested at mesophilic conditions. The reagent iron salts was used to restrain theproduction of H₂S. Experimental findings are as follows:⑴Equivalent relationship between the COD and VSS of primary sludge is1gVSS=1.52gCOD, VSS/SS≈0.51, With the organic matters decreased, VSS/SS wasreduced, ultimately stabilized at0.37.⑵the digestion efficiency of primary sludge is43.64%, gas production unit VSSis0.25g/L, the decomposition unit VSS gas production is0.73g/L,the average dailybiogas yields of primary sludge was3.92m³/m³sludge.It was accountable that60.68%theoretic specific biogas generation.⑶different sludges have different component in the biogas, the biogas producedfrom the primary sludge digested from the fourth WWTP in Xi’an contains2800ppmof H₂S; CH₄:68%; CO₂:31%; N₂＜1%; H₂＜1%.⑷The SMA of digested sludge was0.061LCH₄/（gVSS·d）, the average SMA ofthe digested sludge was0.011LCH₄/（gVSS·d）. This shows that the hydrolysis was theinhibition phase during the sludge anaerobic digestion.⑸The experiment improved that added iron salts can inhibit the production ofH₂S.The concentration of hydrogen sulfide in the biogas decreased from2800ppm to1053.1ppm when iron salt was added. The removal efficiency was62.38%.