192 Organic waste recycling: technology and management
Remedy Inoculation with the right microbial culture. Low initial loading during start-up (approx. 0.1 kg COD/kg VSS/day) Backwashing to remove excess solid build-up in the voids Remove the solids from packing by draining and backwashing the media Amount of seed sludge: 10-15 kg VSS/m
3.
Initial organic load: 0.05-0.1 kg COD/kg VSS/day. No increase of the organic load unless all VFA's are more than 80% degraded. Permit the wash-out of poorly settling sludge. Retain the heavy part of sludge. Keep the gas-liquid interface well stirred to allow entrapped gas to readily escape.
Cause Improper seeding or improper initial loading Gas bubbles adhere to flocs/bed particles and cause these to rise in the reactor Clogging due to too much solids retained in the filter Improper seeding or improper initial sludge loading Ineffective separation of the entrapped or attached gas from the sludge flocs at the gas-liquid interface
Problem Start-up difficulty Channelling and short circuiting High levels of SS in reactor effluent Start-up difficulty Buoying sludge pushed through the aperture and overflow with the liquid effluent
Table 4.20 Problems with anaerobic filters and UASB reactors (Lettings Anaerobic filter UASB
et al.
1983; Vigneswaran
et al.
1986; Henze and
Harremoes 1983)