Effluent from a sand bioreactor can be discharged to three places: surface irrigation, subsurface discharge, or steam discharge under permit. Because sand bioreactor effluent is extremely low in solids, low in ammonia, and low in CBOD5, it is well suited for all three discharge scenarios.
Surface irrigation is described in detail in Ohio State University Extension Bulletin 860, Reuse of Reclaimed Wastewater Through Irrigation.
The very low solids content of sand bioreactor effluent and low BOD5 makes it well suited for subsurface irrigation. Trickle irrigation systems with their very low application rates are disposal options for sand bioreactor effluent. Soil absorption systems are also used to dispose of sand bioreactor effluent. Research suggests that sand bioreactor effluent can be applied to soil absorption fields at loading rates four times higher than septic tank effluent.
At some sites stream discharge may be an acceptable option. Sand bioreactors produce very high quality effluent that is very low in CBOD5, total suspended solids, and ammonia. Sand bioreactor systems also have a built-in, fail-safe mechanism. Unlike most wastewater treatment systems that discharge poor quality wastewater if neglected, poorly maintained sand bioreactors clog up and do not discharge any wastewater to the stream. Sand bioreactors also present an easily detected, early warning of clogging, in that wastewater begins to pond after each dose. When ponding occurs for even a few minutes, preventative measures can be taken early before problems occur. UV light for disinfection also works well, due to the very low suspended solids content, eliminating the concerns of chlorine in renovated wastewaters discharged to streams.