CASE STUDY
Bioaugmentation Provides Cost Effective
Preventative Maintenance in Municipal Collection System
A large Gulf Coast city has the fourth largest municipal collection system in the United States with 5820 miles
(9366 km) of line. Even with a strong grease ordinance, grease accumulates in the lines over a period of time.
This requires a percentage of the collection system maintenance budget to be used for cleaning lines which have
been clogged with grease. Even with a fleet of 14 vacuum trucks, the city could clean lines only once every
64 years. Historically, in areas of heavy grease loading, lines required cleaning as often as every 2 weeks due
to grease back-ups. As the population increases the loading on the system will also increase. Convinced that
more trucks and operators were not a long term solution, authorities began investigating new technologies
to resolve this problem.
This city had already achieved greater than 90% customer satisfaction index based on preventive maintenance
programs and fast customer service. However, to improve the customer satisfaction rating further, the city
sought to use biotechnology to improve effectiveness of preventive maintenance for grease related problems.
With the assistance of Novozymes Biologicals’ field engineers, the city launched a bioaugmentation program
using
BI-CHEM
®
cultures.
The bioaugmentation program targeted lines prone to grease blockage:
• areas with high density of restaurants
• lines downstream from industry such as food processors, bakeries or meat processors
• areas with a high density of apartment complexes
• lines downstream from hospitals, colleges and other institutions
Initially, two lines were selected for pilot treatment. “Site 1” was located immediately downstream from a
popular restaurant. This line had experienced numerous back-ups in spite of a very labor intensive preventative
maintenance program. “Site 2” was a 1.5 mile (2.4 km) stretch of line downstream from a food processor and a
hospital. This line required cleaning quarterly to prevent back-ups. The quarterly cleaning typically required two
vacuum trucks over a five day period of time. When the test began, one manhole in the line was blocked with a
grease “berg” seven feet (2.1m) thick.
A bioaugmentation program was designed for each site with a goal of significantly reducing maintenance due
to grease blockages. The program included treatment with
BI-CHEM DC 2000GL
as a dry product packed either
in a water-soluble polyvinyl SoluPak for ease of application or in a patented BIO-SOCK
®
designed for slow release
of microbes over a period of one to two weeks. In addition,
BI-CHEM LC 2006RG
was poured or sprayed into
the manhole. The seeding dosage of microbes was applied weekly to each manhole in the affected portion of
the line.
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