The core challenge of beer wastewater pretreatment lies in the efficient removal of suspended spent grains (SS 800-5000mg/L) and hot and cold coagulants. However, the traditional process has low sedimentation efficiency and poor sludge removal effect, which leads to the subsequent biochemical system paralysis.
1. Source and characteristics
Beer wastewater mainly comes from saccharification workshop, fermentation workshop and filling workshop. The wastewater indicators of the three workshops are different. The wastewater from saccharification workshop and fermentation workshop accounts for about 30% of the total wastewater. The COD is high and it belongs to high-concentration wastewater, while the wastewater from the filling workshop belongs to low-concentration wastewater.
Beer wastewater contains organic matter such as sugar and alcohol. The organic matter has a high concentration and is non-toxic, but it is easy to corrupt. It consumes a lot of dissolved oxygen when discharged into the water body, which causes serious harm to the water environment.
2. Process selection
At present, most breweries mainly use traditional biochemical methods to treat wastewater, and many newly built breweries use combined processes for treatment. The combined process can save costs and reduce energy consumption, and has a broader development prospect.
Anaerobic-aerobic combined process
A brewery uses IC reactor and aeration tank in series to treat beer wastewater. The economic analysis of the treatment shows that the process has high stability, small footprint, high degree of automation, and cost savings. The residual granular sludge formed in the IC reactor can be sold. The COD value of the treated wastewater is 30mg/L~45mg/L, the removal rate is 86%, and the average SS concentration is 40mg/L. The average SS concentration is 40mg/L~45mg/L, and the average removal rate can reach more than 95%, which can be used for irrigation and greening.
Anaerobic-anoxic-aerobic combined process
The use of this process to treat high-concentration beer wastewater has the following advantages: it has a wider adaptability to wastewater quality than a single treatment process, can shorten the hydraulic retention time (HRT) of wastewater, prevent sludge swelling, has a high organic matter degradation rate, and has good sludge settling performance.
The brewery wastewater is treated by the hydrolysis acidification-sequencing batch sludge process (SBR)-biological adsorption (aeration) series process, which is a typical anaerobic-anoxic-aerobic combination process.
The hydrolysis acidification tank can reduce the pH value of the wastewater and remove part of the COD, improving the biodegradability of the wastewater; the aeration tank can reduce the BOD concentration and reduce the load of subsequent treatment; the biological adsorption can remove about 50% of the organic matter in a shorter aeration time, and the effluent COD and BOD are stable, with removal rates of 98.6% and 93.8% respectively. The entire treatment system is simple and compact, with a short HRT and energy saving and consumption reduction.
In addition, the commonly used combined processes include: hydrolysis acidification-biological contact oxidation process, UASB and oxidation ditch series process, UASB-anoxic tank-contact oxidation process, hydrolysis acidification-biological contact oxidation-external circulation (EC) anaerobic process.
