The Upflow Anaerobic Sludge Blanket (UASB) method is an energy-saving, highly efficient and new anaerobic bio-treatment technology. In our country, Kurita Water Industries and FUJIKASUI ENGINEERING have been developing technical improvement independently on the UASB method since the middle of the 1980s. The companies can mount and commercialize the method. Similarly, the Sumitomo pile machine and Ishikawajima-Harima Heavy Industries (IHI), which obtained license from overseas, have developed the technology.

The UASB method is the optimal technology for effective & efficient processing of biodegradable organic matter by means of anaerobic microorganisms at a higher speed using a compact facility. Such organic matter includes effluents of industrial products like beer, various beverages, commodities from sugar and potato, etc., in which the main ingredients are carbohydrates, volatile fatty acids, and lower alcohol. Among them, beer effluent is a typical example of wastewater which can be degraded anaerobically using the UASB method.

Since a treatment scale is large enough and the economic advantage of anaerobic treatment is easily ensured, the UASB method is being introduced positively compared with other industries. Although there are 33 domestic breweries under operation in Japan as of December 2003, anaerobic treatment facility has been installed in some way or another, except for three breweries.

In the procedure, the general effluent from a brewery is mixed with wastewater from each process, such as mashing, maturing, and packaging. CODcr is between 1,500?5,000mg/L, BOD5 is between 1,000?3,000mg/L ,and SS is between 500?2,000mg/L. There is a considerable wide range between them. The general effluent is composed of the main ingredients, namely volatile fatty acids, such as acetic and propionic acids, as well as carbohydrates, which can be easily decomposed by anaerobic microorganisms into ethanol. In addition, the little inflow of a heavy metal and an inhibitor makes it very suitable for anaerobic treatment.

In this study, the economic efficiency is compared with the processing performance and conventional activated sludge at the Musashino Brewery of Suntory Breweries. In the brewing process, the total amount of general effluent (6000m3/day) can be anaerobically treated by high rate EGSB (High rate UASB: Expanded Granular Sludge Bed). Due to SS (approximately 1,000?1,200mg/L) derivation from malt and hop in the water, it is flown into an EGSB reactor (Super BioSaverR) via an acid formation tank after SS disposal by rough separation screen and high-speed pretreatment precipitation at upward flow speed 6m/hr. (Fig.1) In contrast to the entrance to the reaction tank (CODcr4400mg/L), the capacity of Super BioSaverR is 525m3 x 2 tanks (floor area 35m2 x height 15m x 2 tanks), staying time is 4.2 hours, and the maximum capacity of the total CODcr is approximately 24 kg/ m3/day.

(Fig.1) Super BioSaverR for the Musashino Brewery of Suntory Breweries

Super BioSaverR raises the capacity efficiently by making the reactor oblong, which removes the dead space of the base and makes the capacity of the sludge zone more than 60 to 70% of the total contributing to the reaction. (Fig.2) However, since Water LV (upward flow speed) and Gas LV in a reactor become markedly large as compared with UASB by making a reactor’s cross section area small under high rate conditions, a high-efficient settler becomes indispensable, which can stabilize, segregate, and recollect granules under such severe conditions.

(Fig.2) Super BioSaverR Visual Description

Although the load changed according to the time Super BioSaverR was operated, it was driven basically at 15-20kg CODcr/m3/d, except for two months during the ramp-up period. CODcr removal efficiency was sustained stably with more than 90% if the granule is soluble. Granule multiplied stably from 25tVSS to 40tVSS in two years. However, actual increase was 20tVSS because 5tVSS granule for theother equipments, launched during the period, was extracted and was used effectively.

On the other hand, in the total operation cost for the wastewater treatment equipments, electric power cost was reduced by 53% and sludge was reduced by 57% compared with purely aerobic wastewater treatment before 1987. Furthermore, if gas collection profits due to steam are considered, the total cost for the wastewater treatment equipments indicated approximately 55% reduction after deducting an increase in the cost related to agents, as compared with aerobic treatment. Thus, economic efficiency of anaerobic treatment is demonstrated by UASB in various brewery industries.

UASB has spread rapidly in only 10 years or so after having been introduced into Japan’s breweries in 1987. The environmental person as well as the person in charge of generating the machineries / facilities in each brewery industry has advanced toward environmental improvement and the creation of large cost-cutting measures. This advantage of anaerobic treatment by UASB method outfaces new technology, which was initially pictured as a dream, and is now the fruit of their hard work. Anaerobic treatment is indeed an increasingly noticeable technology in terms of prevention of global warming, which is an ace in the hole for the reduction of CO2 emissions. Continuous technical evolution is expected in simplification of pretreatment, reduction of polluted sludge during post-treatment, nutrient removal, and effective utilization of gas.