The SENTRY system was installed July 2017 at CNETE (Centre National en Electrochimie et en Technologies Environnementales) or National Center in Electrochemistry and Environmental Technologies testing facility in Quebec, Canada.
A system was installed in two duplicate Anaerobic Digesters processing waste activated sludge. A pre-treatment step was added to one of the reactors, and the differences between the systems were analyzed using a SENTRY system installed in each. The sensor is demonstrated to be a key tool in understanding the conditions in test and control AD systems.
For continuing anaerobic digestion activities the sensor could be applied to
(1) Characterizing the impact of pre-treatment on influent wastewater streams,
(2) Providing correlations to real-time biogas production and
(3) Optimizing feed cycle times to ensure removal of bio-available carbon.
The major conclusions from the report are outlined as follows:
(1) Characterizing impact of pre-treatment:
· The pre-treatment accounted a 22.9% increase in biogas production between the test and control system. Further analysis of fractionation of the remaining organic material could be beneficial for understanding the full effect of the pretreatment.
· The pre-treated wastewater showed more consistent activity throughout the week, suggesting the pretreatment was having a good effect of maximizing the biological activity in the reactor. This also suggested that a potentially longer HRT could produce even higher biogas production and removal rates.
(2) Biogas production:
· Biogas production (and therefore reactor activity) trended well with SENTRY output. This shows great promise as a way to fill in the gaps of data that exist in daily sampling.
· This biogas trend was especially helpful for understanding reactor A (no pretreatment) as the batch mode beginning and end was clearly noticed (typically between noon and 7pm). IWT believes additional loading to this reactor could be achieved during times of low MET.
· The pretreatment step has clearly increased the potential for biogas production of the microbes based on the current HRTs of the reactor.
(3) Process feeding monitoring:
· The SENTRY sensors were able to pick up distinct batch run cycles for each system. 3 times higher average biological activity (MET) and longer cycles were noted in the reactor receiving the pre-treated influent (reactor B), suggesting a more biologically active feed material.
· The sensor displayed the weekly patterns of the feed cycle and response to the feed cycle in real time with sensors placed inside the reactors. Feed dates/times can be observed, as well as when reactions inside the system had slowed down.
· SENTRY data provides operator the option to optimize feeding cycles more closely to MET output. Waiting for BES data to return to baseline would be a suitable strategy for optimized cycle times.
CONCLUSION:
The sensor is demonstrated to be a key tool in understanding the conditions in test and control AD systems. For continuing anaerobic digestion activities the sensor could be applied to
(1) Characterizing the impact of pre-treatment on influent wastewater streams,
(2) Providing correlations to real-time biogas production and
(3) Optimizing feed cycle times to ensure removal of bio-available carbon.