Algal coagulation

When algal coagulation is included in this simulation, the formation of aggregates represents a loss of solitary algae that decreases the maximum algal... 

Figure 1. Concentrations of different nitrogen pools for the case in which there is no algal coagulation. Shown are the concentrations of nitrate, phytoplankton (particulate) nitrogen, and total nitrogen (sum of nitrate and particulate concentrations). Decreases in total nitrogen concentration are caused by sedimentation of solitary algal cells. The algae had radii of 10 jun. The mixed-layer depth was 50 m. The shear was 0.1/s. (Reproduced with permission from reference 37.

The modeling of algal coagulation demonstrated that such coagulation would be consistent with oceanic conditions. Effects of such coagulation would include the facts that aggregation could constrain the maximum phytoplankton concentration, that it would enhance transport of material out of the euphotic zone, and that the transition to an aggregation-dominated state could be very rapid. 

Other problems with ion exchangers include coating of the resin beads or zeolite particles with suspended matter from turbid water (pretreatment with a coagulant may be necessary) or algal growths (chlorination of the water may be required). Zeolites may cause significant silica carryover and should not be used to treat boiler water for steam turbines. Finally, although Ca2+ and Mg2+ are objectionable in boiler or laundry operations, they are necessary nutrients in the human diet. Furthermore, excessive consumption of Na+ can contribute to hypertension and other blood circulatory problems. In Canada, for example, the incidence of heart disease and related health problems is lower in areas where the water supply is... 

Representative Results for Coagulation of Algal Bloom Models... 

Large numbers of simulations have shown that the dominant effects of coagulation are the limitation that aggregations put on algal populations and the enhanced rates of export of particulate matter that result from the formation of the large aggregates (36, 37). 

Figure 8. Effect of spines on algal concentrations. Spines increase the effective radius of a particle. Coagulation kernels have been modified by assuming that they make the effective capture radius greater by the length of the spine. There are no grazers. (Reproduced with permission from reference 38. Copyright 1993...

Two simulations of the effects of solid-liquid separation are considered here. From, algae to aquifers, these are, first, a consideration of the effects of coagulation on algal populations and sedimenting algal fluxes in marine waters taken from Jackson and Lochmann (28) and, second, evaluation of the effects of deposition or filtration on the transport of particles in groundwater systems taken from Tobiason (29). 

Jackson, G.A. (1990) A model of the formation of marine algal floes by physical coagulation processes. Deep-Sea Research, 37, 1197-1211. 

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