System
Description
The UNOX-BNR System from Lotepro provides an effective solution to the problem
of phosphorus and nitrogen removal from wastewater. Depending upon the type
of nutrient to be removed, the UNOX-BNR System combines the high purity oxygen
activated sludge process with an anaerobic and/or anoxic process. The basic
elements of a UNOX-BNR System are shown in Figure 1.
The UNOX-BNR System configuration presented in Figure 1 combines the UNOX System
for carbonaceous BOD removal and nitrification, with an anaerobic
stage
for biological phosphorus removal and an anoxic stage for denitrification. Variations
of the UNOX-BNR System include elimination of the anaerobic stage if phosphorus
removal is not required or the elimination of the anoxic stage if denitrification
is not required. When applied, the anaerobic and anoxic stage typically consists
of multiple compartments to optimize operating conditions and assure achievement
of design effluent levels.
Typically an anaerobic process is combined with the UNOX System to provide a
competitive advantage for the polyphosphate storing microorganisms
that are responsible for biological phosphorus removal by absorbing BOD and
accumulating large quantities of phosphorus within their cell structure. The
accumulated phosphorus is removed from the plant with discharge of the waste
sludge. The anoxic process allows metabolism to proceed under conditions where
oxygen is absent and nitrate is present. Under anoxic conditions the denitrifying
microorganisms utilize the oxygen from nitrate as an oxidizing agent for stabilization
of BOD. The anoxic process would follow the anaerobic process if phosphorous
removal was required in addition to denitrification.