P. FongsatitkulD. S. MavinicK. V. LoMahidol UniversityThe University of British Columbia2018-07-042018-07-041995-02-01Environmental Technology (United Kingdom). Vol.16, No.2 (1995), 137-1461479487X095933302-s2.0-0028871254https://repository.li.mahidol.ac.th/handle/20.500.14594/17283This research demonstrated the feasibility of recovery of a UASB-UASB system treating simulated sewage sludge, after operating in a deliberate failure mode. The approach employed an application of step-loading reduction and a modification of the internal recycle ratio (RR). The system recovered exponentially (r2= 0.99) and logarithmically (r2= 0.81), with an increase in HRT (loading reduction), in so far as COD (sol) removal efficiency (92%) and CH4gas production (100%), were concerned. The system appeared to return to its initial stage of operation, after 43 days of recovery period, by the application of a two-step increase in the HRTM-UASBat 1-5 and 5.5 times that of the failure HRTM-UASB(0.63 days); coincidentally, a dimensional time of 5.5 and 10 times the minimum HRT was employed for the overall system and the M-UASB, respectively. © Publications Division Selper Ltd., 1995.Mahidol UniversityEnvironmental ScienceArticleSCOPUS10.1080/09593331608616254