ASABE Technical Library - Abstract
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MASSTC TESTING AND FIELD VERIFICATION OF PIRANA FOR REMEDIATION OF SEPTIC SYSTEMS
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 701P0104, . (doi: 10.13031/2013.15775)Authors: Stephen P. Dix
Keywords: Onsite wastewater treatment, septic drainfield remediation, bioaugmentation, absorption rates, nitrogen reduction
Testing at the MASSTC demonstrates that Pirana pretreatment can increase absorption efficiency
by three to five times over Title 5 septic control trenches. This improvement occurred within
weeks on trenches previously loaded with septic effluent. Pathogen reduction is consistent with
that found for septic effluent when effluent passes through two feet of unsaturated sand. Even
with as little as 12 inches of sand, a three to four log reduction can be anticipated. Unlike
conventional septic control trenches, pathogen reduction improved as temperatures declined.
Digestion of these solids, stored in a septic system over the winter, may explain the higher
nitrogen concentrations in conventional septic systems in early summer. While septic control
trenches showed no net loss of nitrogen, samples from Pirana effluent loaded trenches at the end
of the study showed a total nitrogen reduction of over 60 percent, with levels of less than 10 mg/l
found at the end of the study in January.
Worldstone SepticWatch installed in both the tank and absorption field provides detailed
monitoring of solids and hydraulics, respectively. Hourly readings from this equipment allow
for analysis of hydraulic efficiency, while longer-term daily summaries show climatic impacts on
the systems. When both technologies are combined, documented rapid improvement in
hydraulic efficiency on failed systems shows the potential of this process to extend the life of our
aging septic inventory. In areas seeking to reduce nitrogen, this research indicates that costly
centralized systems, that take years to fund and construct, can be avoided by simply upgrading
the existing pretreatment system.