Evaluation of Walker Lake algal bloom as a fertilizer or biofuel source
Memmott, J. C., P. S.J. Verburg and C. H. Fritsen . 2013.
Abstract
Walker Lake, a saline terminal lake in western Nevada, has recently seen an increase in
frequency of substantial algal blooms forming vast surface accumulations. These blooms have
primarily consisted of the cyanobacteria Nodularia spumigena. Walker Lake has been
undergoing increased salinity and eutrophication as inflows continue to decrease. Among the
measures that can be implemented for nutrient control to decelerate eutrophication is the removal
of nutrients in the form of biomass leading to a net loss of the nutrient content of the lake. This
work has explored the feasibility of harvesting algae produced during nuisance algal blooms in
Walker Lake for fertilizer and/or algal biofuel uses. The molar C:N:P ratio for the material was
28:1:2, which was similar to other commercially available organic fertilizers. PRS™ probes
were used to evaluate the bloom material for use as a fertilizer by mixing collected material with
Nevada soils. The soils contained little organic material and would likely benefit from the
addition, in this regard. The results indicated that N and P from the algal material was not
readily available and may require more time for mineralization in Nevada soils- there was no
substantial N or P release from algal material during the 45.8 day incubation. However, K and S
release increased with increasing additions of algal biomass. It is likely that cumulative N and P
availability would continue to increase, based on trends in the rate of increase at the end of the
experiment. Triacylglycerols and free fatty acids content of the material was found to be low at
0.09% TAG and FFA *FDM-1. The use of enhance processing techniques in addition to
drying-such as processing into biochar or composting before adding to the soil-may be
required to accelerate the availability of N and P and facilitate the conversion and use for energy
by other means than lipids for biodiesel.
Key Words
algae, bloom, Nodularia spumigena, nutrient availability, PRS™ probe, Walker Lake
