Resolve insufficient granule production and loss of anaerobic granules
Problem
Insufficient granule production and loss of anaerobic granules in a high rate anaerobic treatment system
In high rate anaerobic wastewater treatment systems (UASB’s, EGSB’s etc.) the development of granular sludge is a key factor for successful operation of high rate anaerobic treatment systems. Criteria for determining if granular sludge has developed in a UASB or EGSB reactor is based on the densities and diameters of the granular sludge. The composition and shape of granular sludge can vary greatly. Typically, granules are a spherical form with a diameter from 0.14 to 5 mm. The inorganic content varies from 10% to 90% of the dry weight of granules and is dependent on the makeup on the waste stream composition. The concentration of the major cations (calcium, magnesium, iron, potassium, sodium and aluminum) play a significant role here. The concentration of and the bioavailability of the trace elements cobalt, nickel, molybdenum, manganese, copper, zinc, boron, vanadium, selenium and tin also play a role in the formation of granules (via determining which methanogens, acetogens, acidogens and sulfate reducing bacteria/archaea dominate the biocenoces. The extracellular polysaccharide content varies from 0.6% to 20% of the volatile solids and consists mainly of polysaccharides and protein. Due to the energetics of anaerobic bacteria/archaea they do not produce extracellular polysaccharide at near the rate of aerobic bacteria. This limitation in anaerobically produced polysaccharide is paramount in the production of anaerobic granules. Anaerobic biomass that has low concentrations of extracellular polysaccharide will build granules at a slower rate and will also lose granules via washout out of the high rate anaerobic reactor.
Solution
Treat with Granule Maid
Granule Maid is a blended biopolymer that closely resembles the biological polymers produced by anaerobic bacteria and archaea. The addition of Granule Maid assists in a more rapid formation of granular biomass. This phenomena occurs due to enhancement in the flocculation of anaerobic bacteria/archaea leading to a faster sludge formation and higher density of sludge retained in the reactor. Another benefit involved with the introduction of Granule Maid is that it lowers the surface tension of the wastewater. The adhesion of bacteria involved in anaerobic consortia is related to surface thermodynamics. The adhesion of hydrophilic cells are enhanced at a low liquid surface tension. The addition of Granule Maid will decrease the wastewater surface tension and thus improve the granular biomass yield.
A UASB or EGSB start up period can be shortened with the addition of Granule Maid or assist in a more rapid rebuilding of granular biomass when anaerobic granular biomass is lost. The infusion of Granule Maid will also lead to increased anaerobic reactor stability. In addition, the introduction of Granule Maid can assist in lowering effluent VFA and increasing anaerobic gas production. Finally, Granule Maid has some inherent biochemical qualities that can reduce wastes stream toxicants leading to improved gas production and granular biomass yield.
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