408
Y. Argaman et al.
months, Rc provided approximately 50% of the RA nitrification ability and in the
following two-week period reached 100%.
6 Research Status
Due to the technical problems of the wastewater supply, the final phase of the
project including pilot-scale system operation for examination of the system's
performance capability and stability, has not yet been completed. This phase is
currently being conducted and the results will be presented in the final report.
7
Conclusions
Nitrification by immobilized biomass was investigated in this work. The following
conclusions can be drawn from the reported results: the PYA-drying method can
be successfully used for nitrifying bacteria entrapment. This method of bacterial
immobilization is nontoxic to the biomass and provides gel with good physical
properties. This gel is relatively inexpensive and available due to the wide use of
PV A in chemical industries. The ammonia removal rate in the continuous-flow
reactors containing 10% PV A lens-shaped beads with immobilized nitrifying
biomass is in the range of 25 mgNH\-N L· 1 h· 1 • Since the gel content can be easily
increased, the developed immobilized bacteria system can provide effective
nitrification within HRT of 1 h, which can remain for at least 12 months.
The optimal seeded concentration of biomass immobilized nitrifying using
Lentisol and PV A-glycerol gels is 3gVSS L· 1 and 7gVSS L·\ respectively. The
optimal seeding concentration for Lentisol did not result in better nitrification
activity, while initial bacteria density higher than optimal for PV A-glycerol
provide higher volumetric rate of nitrification.
A gel-thread reactor was developed to provide the possibility for better
heterotrophic bacteria washout as well as better substrate mass transfer. The
results demonstrated that nitrification of the synthetic ammonia wastewater by the
biomass immobilized on thread is approximately three times more effective than
by gel beads. Furthermore, the data showed that seeded biomass concentration
might be reduced when applying gel threads.
The selected method for bacteria immobilization was applied to verify the
feasibility of nitrification interruption for agricultural needs. The results showed
that the nitrification rate successfully recovered after 3 months of ammonia
starvation. A reactor that received small ammonia portions on a weekly basis
demonstrated excellent immediate recovery. The system received no ammonium
showed half of the original activity instantaneously on feed renewal. Only 2 weeks
were needed to reach the full original nitrification activity.
Y. Argaman et al.
months, Rc provided approximately 50% of the RA nitrification ability and in the
following two-week period reached 100%.
6 Research Status
Due to the technical problems of the wastewater supply, the final phase of the
project including pilot-scale system operation for examination of the system's
performance capability and stability, has not yet been completed. This phase is
currently being conducted and the results will be presented in the final report.
7
Conclusions
Nitrification by immobilized biomass was investigated in this work. The following
conclusions can be drawn from the reported results: the PYA-drying method can
be successfully used for nitrifying bacteria entrapment. This method of bacterial
immobilization is nontoxic to the biomass and provides gel with good physical
properties. This gel is relatively inexpensive and available due to the wide use of
PV A in chemical industries. The ammonia removal rate in the continuous-flow
reactors containing 10% PV A lens-shaped beads with immobilized nitrifying
biomass is in the range of 25 mgNH\-N L· 1 h· 1 • Since the gel content can be easily
increased, the developed immobilized bacteria system can provide effective
nitrification within HRT of 1 h, which can remain for at least 12 months.
The optimal seeded concentration of biomass immobilized nitrifying using
Lentisol and PV A-glycerol gels is 3gVSS L· 1 and 7gVSS L·\ respectively. The
optimal seeding concentration for Lentisol did not result in better nitrification
activity, while initial bacteria density higher than optimal for PV A-glycerol
provide higher volumetric rate of nitrification.
A gel-thread reactor was developed to provide the possibility for better
heterotrophic bacteria washout as well as better substrate mass transfer. The
results demonstrated that nitrification of the synthetic ammonia wastewater by the
biomass immobilized on thread is approximately three times more effective than
by gel beads. Furthermore, the data showed that seeded biomass concentration
might be reduced when applying gel threads.
The selected method for bacteria immobilization was applied to verify the
feasibility of nitrification interruption for agricultural needs. The results showed
that the nitrification rate successfully recovered after 3 months of ammonia
starvation. A reactor that received small ammonia portions on a weekly basis
demonstrated excellent immediate recovery. The system received no ammonium
showed half of the original activity instantaneously on feed renewal. Only 2 weeks
were needed to reach the full original nitrification activity.