| About 20 or 30 years there exists an efficient and economic new wastewater biological treatment in the field of wastewater treatment- the aerobic granular sludge(AGS) technology.The AGS is a granular aggregates of microorganisms which different from ordinary activated sludge formed by the microorganism condensed under the aerobic conditions in the wastewater treatment system, its shape like spherical or ellipsoidal. it has many features such as: regular shape, compact structure, excellent setting characteristic, rich biological flora,strong ability to deal toxic and hazardous substances, adapting the sudden organic load and hydraulic load, it also has the function of nitrogen and phosphorus removal efficiency at the same time degrade the organic carbon. These advantages have attracted the interest of experts and scholars all over the world and have done a lot of research in order to apply to actual wastewater treatment project.The experiments use a continuous-flow network board reactor to study rapid cultivation of aerobic granular sludge. At the initial study phase, during the process of AGS forming and hyphomycetoma expanding eventually disaggregation, analysis the sludge modality, physical properties and the contamination removal efficiency, also explore the mechanism of aerobic granules formation, hyphomycetoma expanding and stable operation in the main response district. Later through the improvement of reactor, the formation of aerobic granular sludge can run stable for a long time and maintained excellent physical performance and pollutant removal efficiency. Running to the 15 th day, the AGS can be formed in the main response district and maturated at the 22 th day. At the AGS maturated stage, the particle size distribute in the context of 0.5~5.0mm, the maximum subsidence rate can get up to 44.8M/h, sludge volume index is about 21mL/g, the highest concentration of sludge can get up to 5.8g/L, all these reflects the excellent settling properties of AGS. The reactor’s removal rate of COD, TN,NH3-N, TP can get up to 91.75%、82.34%、91.04%、71.45% perspectively.The "promotion district" in the continuous-flow network board plays an important role in the procession of AGS. The biofilms in the network board of promotion district are fallen off under the hydraulic shear power, the fallen biofilms flow to the main reaction district as the initial kernel of microorganism gathered and adhere it to grow which can produce AGS quickly. The hydraulic shear power not only can supply the promotion of fallen biofilms in promotion district, but also plays an key role in AGS formation and maturation in main reaction district. When the surface gas velocity is 2.5cm/s, the growth and fallen of biofilms in promotion district can get balance, also the AGS of the main reaction district has smooth surface, shape, clear boundaries, compact structure; different microorganisms within the reactor in different operation stages, with stair-way to increase water flow to gradually raisethe water organic load which can produce AGS quickly. When the organic water load increased to 4.0 kgCOD/(m~3·d), with the mature of running particle sludge in reactor, matured AGS can run stable about one week with better physical characteristic and pollutants removal efficiency.In the initial research phase, the main reason of hyphomycetoma expanding in AGS is:the hyphomycetoma has bigger specific surface area, better transfer performance. With the reactor running, the sludge loading, the nitrogen and phosphorus content become gradually lower, When the concentration of nutrients is low, the hyphomycetoma has growth advantage,eventually lead to fhyphomycetoma expanding in AGS. When training again, take measures to increase the sludge loading and nitrogen and phosphorus nutrients, the AGS can run stably in long-term. Sludge concentration remained stably at around 5.8g/L, sludge volume load remained stably at around 21mL/g, all these show AGS’s better settling property; the reactor on COD, TN, TP removal rate remained constant at around 90%, 80%, 70% perspectively.Add a constant flow pump directly supply the water to the main reaction area which make the disposal of the pollutants higher than the amount of contaminants in the inlet water, so the real pollutants removal efficiency is better than actual data displaying which showing AGS has a better stable and higher removal efficiency to the pollutants. |
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