Affiliations: Programme of Science and Environmental Management,
ISB-Faculty of Science University of Malaya, 50603 Kuala Lumpur, Malaysia | Institute of Post Graduate Studies University of
Malaya, 50603 Kuala Lumpur, Malaysia
Abstract: This study was conducted to investigate the cause of bulking problem
at the effluent treatment plant (ETP) of a paper recycling plant in Malaysia.
Hypothetically, the effluent is lacking nutrients and could induce the
overpopulation of filamentous bacteria, and further cause the bulking problem
during the effluent treatment using activated sludge process. Experiment to
simulate treatment operations had been set up at laboratory. The simulation
showed that the bulking started to occur after the first cycle of the fed-batch
operation with the typical effluent. To make up the lacking of nutrients in the
effluent, urea (N) and phosphate (P) were added as supplements with the ratio
of BOD:N:P equal to 100:1.0:0.7. The supplemented effluent was again
tested by a simulation study and showed that the bulking problem started to
take place after the third cycle of feeding regime. Bulking problem also
periodically took place in the actual operation when the same supplemented
formula was applied; however the frequency of occurrence was lesser. Therefore,
this study has shown that other than the lack of nutrients, there are other
factors that could cause bulking problem.
