The monitoring approach for a sand bioreactor is dictated by the ultimate point of disposal; either reuse through irrigation or stream discharge. Details on monitoring needed for reuse systems are outlined in Ohio State Extension Bulletin 860, Reuse of Reclaimed Wastewater Through Irrigation in Ohio, for sale at county Extension offices. In general, bioreactor effluent should be monitored for CBOD5 and fecal coliform bacteria when reusing the effluent through irrigation, as shown in Table 3. Also, flow should be monitored using a water meter, wastewater flow meter, or a pump event counter.
| Table 3. Summary of Ohio Basic Bioreactor Monitoring Requirements for Wastewater Reuse Through Irrigation in Systems Less Than 0.15 mgd. | |||
|---|---|---|---|
| Effluent Parameter |
Unrestricted Access Sites |
Restricted Access Sites |
Agricultural Sites |
| Flow | Daily | Daily | Daily |
| CBOD5 | 1 per week | 1 per week | 1 per week |
| Fecal coliform bacteria (when irrigating) |
Daily | Daily | Daily |
Monitoring approaches for bioreactors that are approved for stream discharge are described in detail in Ohio EPA policy 1.10. Table 4 summarizes the monitoring requirements. In general, bioreactor effluent must be monitored for temperature, dissolved oxygen, CBOD5, total suspended solids, turbidity, ammonia, fecal coliform bacteria, chlorine residual, and effluent volume, before stream discharge. Monitoring frequency and number of parameters monitored increases with increasing design flow, poor record of operation and maintenance, previous water quality violations, and sensitive stream considerations.
| Table 4. Summary of Ohio Basic Bioreactor Monitoring Requirements for Stream Discharge.* | |||
|---|---|---|---|
| Effluent Parameter | Design Flow (mgd) Less than 0.025 |
Design Flow (mgd) 0.025-0.1 |
Design Flow (mgd) 0.1-0.25 |
| Flow | Daily | Continuous | Continuous |
| Temperature | 1 per week | Daily | Daily |
| Chlorine residual | 1 per 2 weeks | Daily | Daily |
| Dissolved oxygen | 1 per week | Daily | Daily |
| pH | --- | 1 per week | Daily |
| Suspended solids | 1 per month | 1 per week | 2 per week |
| CBOD5 | 1 per month | 1 per week | 2 per week |
| Ammonia | 1 per month | 1 per 2 weeks | 1 per 2 weeks |
| Fecal coliform bacteria | 1 per month | 1 per month | 1 per week |
| Turbidity | Daily | Daily | --- |
*More frequent monitoring for more parameters is required for large plants. | |||