Of anaerobic biotechnology because of its enormous processing power and potential applications, the hot water treatment technology. Anaerobic contact process from the traditional development of the current popularity of UASB process, anaerobic wastewater treatment technology has matured. Further highlight the development of production and resources, energy consumption, covering factors such as conflicts between the existing anaerobic process is facing serious challenges, especially how to deal with the production brought about by the development of a large number of high concentration organic wastewater, making the R & D necessary technical and economic optimization of the anaerobic process [1]. Efficient processing technology, internal circulation anaerobic treatment technologies (hereinafter referred to as the IC anaerobic technology) is in this context, it is the mid-1980s, has successfully developed by Dutch PAQUES company, and into the international wastewater treatment engineering market, the current been successfully applied to the processing of potatoes, beer, food, and citric acid wastewater treatment [2]. Practice has proved that the ability of the technology to remove organic matter far more than ordinary anaerobic treatment (UASB), and the IC reactor volume, less investment, land occupied, stable, efficient anaerobic treatment is a worthwhile promotion technology.
Anaerobic treatment is a biological wastewater treatment technology, a way to improve the rate and efficiency of anaerobic treatment, to provide a good growth of the microbial environment, maintain a high concentration of sludge in the reactor, and a good mass transfer is two key initiatives.
Anaerobic contact process as the representative of the first generation of anaerobic reactors, sludge retention time (SRT) and hydraulic retention time (HRT) in the same reactor sludge concentration is low, and deal with poor results. In order to achieve better treatment effect, the wastewater in the reactor usually stay a few days to the dozens of days long.
2nd generation anaerobic reactor UASB Process, relying on granular sludge formation and three-phase separator, so the sludge retention in the reactor to achieve the SRT> the HRT, thereby increasing the reactor sewage mud concentration, but the mass transfer process of the reactor is not ideal. To improve the mass transfer effects, the most effective way is to increase the surface hydraulic loading rate and surface gas load. However, the high loads generated by the churning of the reactor will sludge in a fully expanded state, so that the original SRT> HRT change to the direction of the SRT = HRT, sludge excessive loss of treatment effect of variation.
Two IC reactor working principle and technical advantages
1, IC reactor works
The basic structure of the IC reactor shown in Figure 1, it is similar to Layer 2 UASB reactors in series. By function, the bottom-up reactor is divided into five zones: the mixing zone, an anaerobic zone, the anaerobic zone, the settling zone and gas-liquid separation zone.
Mixing zone: the bottom of the reactor water, the mud mixture of granular sludge and gas-liquid separation zone backflow effectively mixed in this area.
An anaerobic zone: a mixture of mud formed by the mixing zone into the area in the sludge under high concentration, most of the organic matter into biogas. Severe disturbance of the mixture of upwelling and biogas sludge so that the reaction zone was the expansion and fluidization state, to strengthen the mud surface contact, the sludge which maintained high activity. With the increase in biogas production, part of the mud mixture biogas upgrading to the top of the gas-liquid separation zone.
Gas-liquid separation zone: mixture of methane was promoted with the mud separation and export processing system, mud and water mixture is returned along the return pipe to the bottom of the mixing zone with the bottom of the reactor sludge and water mixing, internal circulation of the mixture.
Anaerobic zone 2: an anaerobic treatment of wastewater, in addition to part of biogas upgrading, and the rest through the three-phase separator into the anaerobic zone. Lower sludge concentration of the area, and the majority of organic matter in the wastewater in an anaerobic degradation, the biogas produced is less. Biogas through biogas pipe to import gas-liquid separation zone, the anaerobic zone of disturbance is very small, provided favorable conditions for the sludge to stay.
Precipitation zone: two anaerobic mud mixture the solid-liquid separation in the settling zone, the supernatant from the outlet pipe to drain away, the precipitation of particles of sludge return to the anaerobic sludge bed.
Be seen from the works of the IC reactor, the reactor through two layer three-phase separator to achieve SRT> HRT, high sludge concentration; severe disturbance of the biogas and the inner loop, so that the mud full access, access to good mass transfer effect.
Three IC process technology advantages
Construction and working principle of the IC reactor determine the influencing factors in the control of anaerobic treatment has more advantages than any other reactor.
High volumetric loading (1): high sludge concentration in the IC reactor, large amount of micro-organisms, and there exists a cycle, the effect of mass transfer, the influent organic load can be more than three times more common anaerobic reactor.
(2) to save investment and covers an area of: IC reactor volumetric loading rate of ordinary UASB reactor about three times its volume equivalent to the ordinary reactor 1/4 to 1/3 greatly reduces the infrastructure of the reactor investment [5]. IC reactor height to diameter ratio is large (typically 4 to 8), it covers an area of particularly provinces, and is ideal for the shortage of land, industrial and mining enterprises.
(3) shock resistant capability: treating low strength wastewater (COD = 2000 ~ 3000mg / L) in the reactor loop flow up into the water 2 to 3 times; deal with high-strength wastewater (COD = 10 000 ~ 15000mg / L), within the circulating water flow of up to 10 ~ 20-fold [5]. A lot of recycled water and water well mixed, harmful substances in raw water are fully diluted, greatly reduces the impact of toxicants on the anaerobic digestion process.
(4) on the cold resistance: the impact of temperature on the anaerobic digestion digestion rate. IC reactor temperature on the anaerobic digestion because it contains large numbers of microorganisms, becomes no longer significant and serious. Usually the IC reactor, anaerobic digestion can be carried out at room temperature (20 ~ 25 ° C), thus reducing the digestion of the difficulties of insulation to save energy.
(5) has the ability to buffer pH: within the circulation flow is equivalent to an anaerobic effluent recycle, use the COD conversion of alkalinity, a dampening effect on the pH, and intracellular pH in the reactor to maintain the best condition, but can also reduce water investment and alkali content.
(6) internal automatic cycle, without external power: the return of the ordinary anaerobic reactor is achieved through external pressure, while the IC reactor to enhance the driving force to achieve self-generated biogas as the mixture within the cycle, do not set the pump to force cycle, saving power consumption.
(7), good water stability: the use of two the UASB series classification of anaerobic treatment, the adverse effects of high K s produce can compensate for the anaerobic process. Van Lier [6] proved in 1994, the classification of the reactor will reduce the effluent VFA concentration and prolong the biological residence time, to stabilize the reaction.
(8) start the cycle short: IC reactor sludge, rapid proliferation of biological, provide favorable conditions for the quick start of the reactor. IC reactor startup cycle is generally one to two months, while the ordinary UASB start the cycle up to 4 to 6 months.
(9), biogas utilization high value: the reactor to produce biogas with high purity, CH4, 70% to 80% of CO2 of 20% to 30%, other 1% to 5% organic, can be used as a fuel [8] .
4, IC processing technology and future prospects of
IC processing technology from its inception has been successfully applied to the processing of potatoes, chicory processing, beer, citric acid and papermaking wastewater treatment. The Netherlands in 1985 the first application of the IC reactor processing of potato processing wastewater, the volume load (as COD) of up to 35 ~ 50kg / (m3 · d), the residence time for 6 h [9]; the treatment of similar wastewater UASB reactor The volume load of only 10 to 15 kg / (m3 d), the residence time up to a dozen to tens of hours [3].
Beer wastewater treatment process, the IC technology used more, China has three breweries to the introduction of this technology. Run results, the IC process the volume load (total COD) of up to 15 to 30 kg / (m3 d), the residence time of 2 ~~ 4.2 h, COD removal efficiency ηCOD> 75% [9]; while the UASB reactor volume load of only 4 to 7 kg / (m3 d), the residence time of 10 h.
Organic wastewater for treatment of high concentration and high salinity, the IC reactor also has a successful experience. The COD of about 7900mg / L, SO42-250mg / L, Cl-is 4200mg / L 22m high, 1100m3 volume IC reactor volume load (as COD) of 31 kg / (m3 · d), ηCOD> 80%, the average residence time of 6.1 h,.
Five, the IC reactor Ordering Information
A. Ordering unit should provide detailed water quality information before placing an order.
Two. Our water quality, quantity, and the floor plan provided by the user, to design the layout of the systems engineering and water distribution structures dimension drawings.
3. The factory can manufacture special models and special equipment of water quality based on user needs.
