Study On The Applicability Of High Pressure Homogenization-hydrolytic Acidification Treated Primary Sludge As Denitrification Carbon Source

The carbon source shortage problems have become increasingly prominent in the urban sewage treatment process, the sludge reduction and resource utilization have also been concerns. In this paper, the key factors that affect primary sludge high-pressure homogenization-hydrolytic acidification (HPH-HA) process were investigated and optimized; The applicability of high pressure homogenization-hydrolytic acidification treated primary sludge as denitrification carbon source was evaluated by simulating the SBR model and examining the nitrogen removal efficiency.The primary sludge HPH-HA process investigation showed that, the optimal hydrolytic acidification conditions for primary sludge were:the optimum high pressure was 40 MPa, pH not required to be adjusted, medium temperature 35℃, rotatation speed 100 rpm. The SCOD concentration was 2313.75 mg/L, after the hydrolytic acidification for sludge homogenized at a pressure of 40 MPa,, far more than that of untreated sludge (600.5 mg/L), and VFA production was 1147.347 mg/L. The sludge disintegration degree increased with pressure, the highest disintegration degree could reach 4.71%, but also declined as sludge concentration increased. The ammonia nitrogen releases increased with pressure, the largest release was 267.9 mg/L, while the phosphorus releases were relatively lower, mostly below 25 mg/L.The hydrolytic acidification of primary sludge might mainly reacted on the first three days, partial acidity or alkalinity, higher or lower temperature were not suitable for sludge acid production:The VFA production from unadjusted sludge was the highest, the VFA production, SCOD, nitrogen and phosphorus releases concentration were 643.8 mg/L,830.5 mg/L,59.2 mg/L and 7.33 mg/L, respectively; Acetate, propionate and n-butyric acids constituted 57.0-73.5%,11.0-18.5% and 4.7-8.8% of the total VFAs, the proportions of acetate acid increased as alkaline addition increased, but the propionate and n-butyric acids proportions generally decreased with pH. The higher the temperature, the more nitrogen and phosphorus releases, The effect of sludge concentration was significant on sludge acid production, acid production and nitrogen release increased with sludge solid content, the VFA production from primary sludge with 21 g/L solid content was 2028.9 mg/L, the SCOD concentration was 3326.0 mg/L.The applicability investigation of high pressure homogenization-hydrolytic acidification treated primary sludge as denitrification carbon source showed that:The hydrolysis acidification liquid of primary sludge homogenized at 40 MPa was the opitimal carbon source, the optimal nitrogen removal condition was:The carbon source was controlled at a C:N ratio of=7.5:1, added at 40 min after stirring, the COD removal could be around 92.9%, the effluent ammonia can be reduced to about 2.7 mg/L; The effluent TN concentration was 13.4-17.0 mg/L, the highest total nitrogen removal could reach 76.7%, finally fluctuated between 71.1%-74.0%; The nitrate concentration finally stabled between 10.5-13.9 mg/L, the effluent concentrations were close to urban sewage discharge level A standard.