Section 16. PHYSICAL/BIOLOGICAL SYSTEMS
HORIZONTAL-BAFFLED ANAEROBIC REACTOR FOR
TREATING DILUTED SWINE WASTEWATER
P. Y. Yang, Professor
C. Y. Chou, Graduate Research Assistant
Agricultural Engineering Department
University of Hawaii at Manoa
Honolulu, Hawaii 96822
INTRODUCTION
In the past decade, the anaerobic lagoon process has been used as the primary biological waste
management system by most hog producers in the United States including the state of Hawaii. Application of an anaerobic lagoon system will be ideal for the location where land area is available
and problems of urban pressures are not obvious. The swine industry in Hawaii is characterized by
numerous farms operating on small land holdings close to residential areas. Operation of an anaerobic lagoon system, apparently, may not be appropriate in the state of Hawaii. Therefore, a series
of preliminary and field studies for integrating an anaerobic treatment process with sludge recycling
(not anaerobic lagoon process) and an algal biomass treatment process for swine wastewater in Hawaii were studied and reported previously [1, 2, 3, 4J. These studies have indicated that integrating
these two biological treatment processes is technically feasible for pollution control, bioenergy production, and utilization. However, these previous studies were limited to treating highly concentrated
swine wastewater. In a current project, Oleszkiewicz and Koziarski [5] overviewed the swine wastewater treatment process and revealed the lack of data on the treatment of dilute swine wastewater
all over the world. They also suggested that the diluted swine wastewater should be treated in the
systems having high solid retention time (SRT) and low hydraulic retention time (HRT). Several
innovative anaerobic reactor configurations including attached film expanded bed process [6], anaerobic fixed film reactor [7, 8], upflow solid blanket or sludge bed process [9, 10], 2-phase digestion
process [11], immobilized-microbia! process [12], and sludge recycling process [2, 3, 4, 13] have been
investigated by using various types of organic wastewater in order to increase the SRT's. In general,
all of these various types of anaerobic treatment processes are capable of achieving the goal of increasing the SRT's. However, each process configuration has its associated weaknesses and disadvantages when pumping requirement, structure of reactor, requirements of operation, and maintenance
are involved in design and operation.
As indicated by Frostell [10], the capital or construction cost for anaerobic filter and the optimal
condition for appropriate formation of sludge bed in the anaerobic sludge bed process are the two
major setbacks for applying these processes in the treatment of highly diluted organic wastewater.
Although anaerobic contact process with sludge recycling may be effective in the treatment of highly
diluted organic wastewater, more kinetic studies on this process are required in order to deliver the
highest possible methane yield and effluent quality [14]. Therefore, if an anaerobic reactor could be
designed to provide an effective increase of SRT, low capital cost and simple operation, it should be
appropriate in treating the highly diluted swine wastewater.
MATERIALS AND MF.THODS
Supernatant of settled swine wastewater, having Total Volatile Solid (TVS) concentration under
2 g/liter, was collected from the Waialee Livestock Research Farm (WLRF), Hawaii Institute of
Tropical Agriculture and Human Resources (HITAHR) and used as a feedstock for the study of
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