Research On The Growth Of Chlorella.sp And The Uptake Of Dissolved Solid In The RO Brine

Serious shortage of the fresh water is the whole world’s problem, which led to a largenumber of desalination plants being built. The emergence of those plants greatly alleviated thecrisis caused by the lack of fresh water, but during the running of those plants, large amountof reverse osmosis concentrate with super high salinity was produced. The management andtreatment of RO brine is a difficult and urgent problem. The traditional methods includedischarge to the surface water, evaporation ponds, wastewater treatment plants and deep wellinjection etc, which are high-cost, narrowly applied or harmful to the environment potentially.In this research, microalgae was cultivated in the RO brine, on one hand, the dissolved solidsin the brine were removed by the microalgae, which provided an environmental friendly wayto treat RO brine. On the other hand, cells of microalgae contained more lipids and the recycleand reuse of resources could be achieved.In the paper, the ability of microalgae (Chlorella.sp) to grow in reverse osmosisconcentrate and the ability of microalgae to remove dissolved solid from the RO brine wereexplored. The results of the experiments demonstrated that chlorella grew well in0-90%RObrine, so RO brine was a good medium for chlorella to grow. Generally speaking, the range of20-50%RO brine facilitated chlorella to grow, in which more biomass could be accumulated.Usually chlorella grown in the30%RO brine could get the maximum biomass and then withthe increasing concentration of RO brine, the accumulated biomass of chlorella decreased.The amount of biomass at20°C>10°C>30°C, at30°C, the lowest cells’ growth ratehappened, an inhibitory effect on the growth of chlorella was obviously observed. In addition,the best specific growth rate of the chlorella grown in the primary effluent mixture, in thesecondary effluent mixture and in the digester supernatant all happened on the first day, are0.52/d,0.49/d and0.32/d respectively. Also, the experimental results showed that removalof dissolved solid in the RO brine, such as calcium ions, magnesium ions, sodium ions,potassium ions, sulfate ions and chloride ions, etc. However more resea rch on its exact removal mechanism is needed.