UASB reaction equipment

详细：

ShengLiuShi UASB Anaerobic Sludge Bed (Up flow Anaerobic Sludge Bed, note: hereinafter referred to as UASB) process with Anaerobic 

filter and the dual characteristics of Anaerobic activated Sludge process, as to be able to convert the pollutants in wastewater into a 

renewable clean energy, biogas technology.It also has a strong adaptability to sewage with different solids, and its structure, operation, 

maintenance and management is relatively simple, the cost is relatively low, the technology has been mature, is getting more and more 

attention from the sewage treatment industry, has been widely welcomed and applied. 

In 1971, professor Lettinga of Wageningen agricultural university in the Netherlands invented the three-phase separator by means of 

physical structure design and taking advantage of the difference in the action of gravity field on materials of different densities.The 

residence time of activated sludge was separated from that of wastewater to form a prototype of UASB reactor.CSM company in the 

Netherlands in 1974 when its 6 m3 reactor beet sugar refinery wastewater treatment, found that the formation mechanism of immobilized

 activated sludge itself biological polymer structure, the granular sludge (granular sludge).The appearance of granular sludge not only

 promotes the application and development of the second generation anaerobic reactor represented by UASB, but also lays a foundation 

for the birth of the third generation anaerobic reactor.

UASB consists of three parts: sludge reaction zone, gas-liquid-solid three-phase separator (including precipitation zone) and gas chamber.

There are a lot of anaerobic sludge in the bottom reaction zone, and the sludge with good settling and condensing properties forms the 

sludge layer at the bottom.The sewage to be treated flows from the bottom of the anaerobic sludge bed into the sludge layer where the 

sludge is mixed with contact. The microorganisms in the sludge decompose the organic matter in the sewage and convert it into methane.

Biogas constantly released in the form of tiny air bubbles, small bubbles in the process of rise, merger, gradually form a larger bubbles, 

upper part in the sludge bed due to gas stirring a lower a sludge concentration of sludge and water together up into three phase separator

, biogas encounter a baffle plate at the bottom of the separator, folding to the sides of the baffle, and across the water into the air 

chamber, concentrated in the gas chamber biogas, catheter is used to derive the, solid-liquid mixture after reflection into the three-phase 

separator of precipitation area, in sewage sludge flocculation, particles increases gradually, and under the effect of gravity settlement.

Sludge deposited on the inclined wall slides back to the anaerobic reaction zone along the inclined wall, so that a large amount of sludge 

is accumulated in the reaction zone. The treated effluent after separation from the sludge overflows from the overflow weir in the 

sedimentation zone, and then drains out of the sludge bed.

(1) provide favorable physical, chemical and mechanical conditions for sludge flocculation, so as to obtain and maintain good precipitation

 performance of anaerobic sludge;(2) a good sludge bed can often form a fairly stable biological phase, maintain a specific micro-ecological

 environment, can resist strong disturbing force, the larger floc has a good precipitation performance, so as to improve the sludge 

concentration in the equipment;(3) by setting a sedimentation zone in the sludge bed equipment, the sludge fine particles are further

flocculated and precipitated in the sludge layer of the sedimentation zone, and then flow back into the sludge bed.

The difficulty of starting UASB equipment is to obtain a large amount of anaerobic granular sludge with good sedimentation performance.

The best way to acclimate, generally take 3-6 months, if the equipment on its own accumulation, the production period can be as long as

 1-2 years.The practice shows that adding a small amount of carrier is conducive to the attachment of anaerobic bacteria and the

 formation of granular sludge in the early stage.Granulation is easier than that of major flocculent sludge;Anaerobic sludge with higher 

activity than methane can shorten the start-up period.

(1) it is better to add enough inoculation sludge at one time;

(2) the sludge flowing out of the sludge bed at the initial stage of start-up can not be returned, so that the especially light and fine sludge

 and suspended solids can be continuously discharged from the sludge bed, so that the heavier activated sludge can accumulate in the bed

, and promote its proliferation to granulation;

(3) when the COD concentration of wastewater is relatively low, the sludge granulation speed may not be accelerated;

(4) the initial sludge load rate is generally about 0.1-0.2kgCOD/ kgtss. d is appropriate;

(5) before the original and anaerobic decomposition of various volatile acids in sewage can not be effectively decomposed, the organic 

volume load should not be arbitrarily increased, which requires follow-up observation and water sample analysis;

(6) when the removal rate of biodegradable COD reaches 70-80%, the loading rate of organic volume can be gradually increased;

(7) in order to promote sludge granulation, the minimum tower velocity in the reaction area should not be less than 1m/d. The higher 

surface hydraulic load is conducive to separating the small granular sludge from the sludge flocculation, so as to make the small granular

 sludge coagulate into large particles.