thermophilic anaerobic membrane bioreactor for pulp and paper sludge treatment
abstract
pulp and paper mills generate a significant amount of organic waste (primary and secondary
sludge) that requires treatment and disposal. currently, pulp and paper sludge (pps) is either
dried for incineration or used for landfilling. however, the dewatering and drying of sludge
before incineration is an energy extensive process and landfilling is associated with a high cost
and low public acceptance, the practices of landfilling will tend to decrease. recently, anaerobic
digestion is considered a cost-effective alternative to a small environmental footprint and has
been researched widely. similarly, anaerobic digestion of pps has the limitations of a large
reactor size, high capital cost, and reduced quality of effluent. thus, it is highly desirable to
search novel technologies for pps treatment and disposal. in this study, a new insight was that
thermophilic anaerobic membrane bioreactor (thanmbr) was developed for pps treatment and
disposal for biogas production because it can overcome some advantages of conventional
anaerobic digestors.
in this study, a laboratory-scale thanmbr was operated for 328 days to assess the biological
and membrane performance of the thanmbr at different hydraulic retention times (hrts) and
different types of pulp and paper secondary sludge. in the first part of this thesis, the biological
performance of thanmbr are discussed by effluent, organic loading rate (olr), chemical
oxygen demand (cod), biogas production rate, biogas composition, biogas yield and suspended
solid destruction. the results showed that the performance of a higher hrt is better than a low
hrt, but the performance of ultrasonic pretreatment on pps does not improve all properties. in
the second part of this thesis, the membrane performance of thanmbr was discussed by: flux,
transmembrane pressure (tmp), membrane fouling, particle size distribution, extracellular
polymeric substances (eps), soluble microbial products (smp), morphology and pore size
distribution. the results suggest that thanmbr is feasible for pps treatment, but the membrane
fouling should be minimized. operating thanmbr at a higher hrt is more attractive than at a
lower hrt from the biological performance point of view.