635 Davis Hall # 1710
Berkeley, CA 94720-1710
(510) 642-5337
jenkins@ce.berkeley.edu
Causes and control of nocardioform NoBF growth and foaming in
activated sludge
Nocardioforms NoBF are actinomycetes that can grow in activated sludge
in a form that causes flotation of the activated sludge culture through
air bubble attachment. Research has been conducted to determine the conditions
favoring the growth of these organisms in activated sludge and to develop
process modifications that select against their proliferation. We have
established a relationship between the growth rate of nocardioforms and
the growth rate of activated sludge and the temperature of operation. The
use of aerobic, anoxic and anaerobic selectors in preventing nocardioform
growth has been studied and applied in full-scale plants. The effect of
pH on the growth kinetics of the nocardioform Gordona amarae has
been studied in pure culture. The interaction of surfactants and nocardioform-containing
activated sludge in producing stable foam has been investigated. Findings
suggest that low pH values favor nocardioforms and that partially degraded
branched chain non-ionic detergents may enhance nocardioform foaming in
activated sludge. The foaming ability has been incorporated into a classifying
selector for selective foam wasting from activated sludge, which has been
tested in the laboratory and at full-scale. The fate of nocardioforms in
anaerobic digestion has been investigated utilizing immunofluorescent antibody
techniques to detect the nocardioforms in the digesting sludge. While nocardioforms
are slowly inactivated by anaerobic digestion their ability to produce
foam survives through long periods of anaerobic digestion. The use of 2-stage
digestion (acid then methanogenic) enhances nocardioforms degradation by
anaerobic digestion. Nocardioform growth and foaming topics currently under
investigation are the effects of thermophilic anaerobic digestion, aeration
basin configuration, surfactants, polymers and sludge age control methods.
Enhanced biological phosphorus removal Enhanced biological phosphorus removal (EBPR) is an activated sludge process modification which allows a high degree of phosphate removal from wastewater. The process is comprised of an initial anaerobic reactor followed by an aerated (aerobic) basin. Research in our laboratories has determined the limiting activated sludge growth rate for EBPR for a range of temperatures. A rapid chemical method has been developed for determining the readily biodegradable fraction of wastewaters - a parameter that is important in determining the efficacy of EBPR for a particular wastewater. The stoichiometry of important EBPR metabolisms has been established for highly enriched EBPR cultures. The effect of the products of EBPR on activated sludge settling characteristics has ben determined. An important microorganism in EBPR was shown to be a close relative of Rhodocyclus and its population was shown to be proportional to the phosphorus content of the activated sludge. Current work is on the use of EBPR to treat phosphorus-deficient wastewater and non the identification of the metabolic control mechanisms of EBPR.
Novel Wastewater and Sludge Treatment Processes Current investigations include projects on the use of membrane bioreactors in a wastewater reclamation treatment train and for secondary wastewater treatment; the use of thermophilic anaerobic sludge digestion processes for pathogen removal and the use of metal salts to prevent the leaching of phosphate from wastewater sludges applied to land.