| Aerobic granular sludge is self-aggregated bio-particles by microorganisms under certain conditions, which has compact structure, good settling ability and perfect biological activity. Because of the mass transfer limit induced by the complex structure and big particle size of granular sludge, there could be different kinds of oxygen and substrate conditions in single granule, which could be propitious to various microorganisms. So different metabolism could simultaneously happen inside of granules, which makes the aerobic granular sludge become a perfect carrier realized the simultaneous biological nutrient removal. The aerobic granular sludge is hard to promote, because its formation time is too long and the H/D of reactor is too large. In this study, a pilot-scale and low H/D SBR is used to treat sewage. The characteristics of granular sludge is investigated. In order to shorten the formation time of aerobic granular sludge, we study the formation process and characteristics under the strengthening granulation conditions by putting coagulant into the SBR at the preliminary stage of the formation.The H/D of SBR is 3.75 and 5. Granular sludge is directly cultivated through activated sludge acted as seed sludge and NaAC acted as nutrients. During the acclimation period and the stable operation period, COD organic load is 2.47-3.84 kg/(m3·d), C:N:P=100:5:1, surface upflow air veloeity is 0.053～0.110 cm/s. The granules are tawny, looks like fine sand. Activated sludge and Granular sludge are both in the reactor. Sludge settling performance has been greatly improved by 144.82 ml/g dropped to 62.74 ml/g. The reactor biological degradation ability in the process is studied by monitoring the COD, NH4+-N and TP of the effluent. The average removal efficiencies of COD, NH4+-N and TP were 85.61%,90.48% and 64.82%, respective.Coagulation and urban water treatment technology combined together to strengthen the formation of granular sludge by adding PAC. It is found that when the concentration of PAC was 180 mg/L, with the aeration to provide shear stirring, granular sludge settle ability is further improved. PAC dosing has some influence on the removal rate of carbon, nitrogen and phosphorus in SBR. PAC effectively improves the removal of COD and TP, but depress the removal of NH4+-N to certain extent.In order to improve the effectiveness of stirring, using patented technology of Jiangyu company, we do the experiments to test the removal of turbidity with two glass reactors. The results show that in the situation of small cross section and fast flow rate, which can have a good effect on the stirring action of the diaphragm. We put the diaphragm into a casing. After this cycle, aerobic granular sludge forms quickly, and we trained visible aerobic granular sludge. The average date nearly reaches 0.65 mm, SVI reaches 52 ml/g. The average removal efficiencies of COD, NH4+-N and TP were 90.27%,72.65% and 89.46%.In order to find a better operating condition, the dissolved oxygen of SBR reator is studied when the air flow is 0.3m3/h,0.5m3/h and 0.8m3/h. We measure the reactor effluent at different air flow in a cycle, and analyze its effect on the removal of contaminants. Pollutant removal efficiency increase with the aeration. Pollutant removal rate increase is not unlimited, it reaches a certain value will not increase.Aerobic granules SBR had been stably operated for 100days, with the perfect pollutant simultaneous removal performances during the operation process. Researches show that in the SBR reactor which is low height-diameter ratio, the low amount of aeration, adding PAC to strengthen sludge granulation and diaphragm stirring are beneficial to the formation of aerobic granular sludge and processing performance of system. |
PDF Full Text Request