Problems Sand bioreactors have a reputation of producing extremely high quality effluent even with fluctuating waste loading. Sometimes an individual reactor is plagued with poor performance.
Poor performance is usually the result of short circuiting through the bioreactor.
Short circuiting can occur along the edges of the bioreactor if it is neglected and allowed to pond. Short circuiting may also occur along discharge, vent, or inspection pipes that extend through the sand. Diversion collars placed around the pipes, just below the sand surface, can be retrofitted if this begins to happen. Another source of short circuits is channels through the sand. Channels seldom form if the wastewater is applied in small doses.