Complex sentence: Because liquid effluent is discharged almost immediately on entering the digester, little dissolved oxygen would be consumed by the wastewater going through the filtration stage but oxygen demand is leached into the wastewater flow through the filter as worms digest retained solids.
Split into simpler sentences: Because liquid effluent is discharged almost immediately on entering the digester, little dissolved oxygen would be consumed by the wastewater going through the filtration stage. However, oxygen demand is leached into the wastewater flow through the filter as worms digest retained solids.