|
With the increase in the amount of urban waste water treatment, the expansion of the sewer connection rate to improve and activated sludge (AS) system to produce a lot of excess sludge the newborn excess sludge reduction and resource to become a new international trend. More economical compared with the currently mainly used at home and abroad ultrasound, ozone oxidation, chlorine oxidation, hot solution, hot alkali treatment sludge reduction technology, based on the growth of microorganisms recessive biological thermophilic enzymes were dissolved (S-TE) technology efficient, safe, easy operation and control, and investment, running costs and effects ideal combination of the follow-up process can be achieved not only sludge \good prospects. Screened from soil isolated a thermophilic bacteria AT07-1, and a preliminary identification of its morphological characteristics and physiological and biochemical properties. The test results show that the AT07-1 strains can secrete extracellular protease and amylase, growth optimum temperature between 45-70 ℃, the growth of the optimum pH of 5.5-8.5, the optimum growth temperature of 65 ° C was identified as Bacillus thermophilic bacteria AT07-1 (FJ231108), has a good the sludge dissolving effect, suitable as a S-TE sludge dissolved inoculum. Residual sludge in the culture of the thermophilic bacteria AT07-1 was inoculated into the different concentrations (TSS about 7.5,14.5,20.5 g · L-1) at 65 ℃ thermophilic bacteria dissolution test, and the unvaccinated test The contrast and VSS dissolved kinetic analysis. The results show that there are two kinds of reactions (enzyme-catalyzed reaction and the thermal hydrolysis reaction) and two processes, S-TE sludge dissolved. Thermophilic bacteria extracellular enzymes (mainly proteases and amylases) the first depolymerization sludge micelles, the bacterial cell wall and then dissolved organic substance in the intracellular hydrolysis inoculation thermophilic bacteria AT07-1 to promote the dissolution of the sludge suspended solids. 60h when inoculated with VSS dissolution rate were 61.41%, 53.79%, 41.86% and the than without vaccination trials over the same period increased by 27.57%, 25.24% and 16.26%, respectively. FSS dissolution rate difference in the vaccinated and unvaccinated tiny, TSS dissolution of the reduction depends on the composition ratio of the VSS and FSS. VSS dissolution process under the test conditions found a kinetic model in the initial stage (t = 3d) after inoculation, significantly increased the dissolution rate constant Kd, were increased from 0.12 d-1, 0.08 d-1, 0.09 d-1 0.27 d-1, 0.24 d-1, 0.13 d-1. This study investigated the impact of the changes of various nutrients in the remaining the sludge dissolved and sludge in S-TE pretreatment at 65 ℃, micro-aeration conditions. Bacillus thermophilic bacteria AT07-1 culture was inoculated into two different concentrations (TSS were 14,21 g · L-1), the remaining sludge and compared with unvaccinated test results showed that inoculation of thermophilic bacteria AT07 -1 than non-inoculated promote the dissolution of the suspended solids in the sludge; micro-aeration inoculation conditions under the greatest accumulation of soluble COD (SCOD) and volatile fatty acids (VFA), the maximum cumulative amount of SCOD to 8222 mg / L, respectively, 11265mg / L; VFA were 4285 mg / L, 5578mg / L, which is conducive to anaerobic digestion gas production; Protein the sludge dissolved generate the rapid hydrolysis by proteases, protein concentration first increased and then decreased; overall total sugar concentration first rose high and then decreased; slightly lower pH increased at first. The study also explores the application of S-TE the pretreatment remaining sludge, either vaccination hydrogen-producing bacteria (Enterococcus sp.LG1) and unvaccinated hydrogen-producing bacteria, anaerobic fermentation hydrogen production, and the corresponding temperature (65 ° C) heat pretreated sludge fermentation hydrogen production compared. The results show that, by the S-TE pretreatment, sludge in unvaccinated external hydrogen-producing bacteria, hydrogen production, the maximum hydrogen production rate (H2/VS) is up to 16.3 mLH2 / g, higher than the 65 ° C heat pretreatment sewage mud vaccination hydrogen-producing bacteria (Enterococcus sp.LG1) 15.6%, higher than the 65 ° C heat pretreatment sludge unvaccinated 26.4% hydrogen-producing bacteria, the only fermentation gas containing H2 and CO2, free of CH4, hydrogen delay time is short (3 -4h), the maximum value of the hydrogen production rate was stable to maintain more than 10h; S-TE the pretreated sludge vaccination production of hydrogen bacteria, hydrogen production is ineffective, the maximum hydrogen production rate was only 10.7 mL / g.
|