This study evaluated how Synechocystis sp. PCC 6803 responds to high total dissolved solids (TDS) associated with eliminating nutrient limitation during long-term operation of a photobioreactor. The unique feature is that the TDS were not dominated by Na+ and Cl-, as in seawater, but by HCO3- and NO3- from nutrient delivery. The TDS-stress threshold was about 10g/L. Whereas inorganic N and P limitations slowed the rate of inorganic C (Ci) uptake in the light, TDS stress was manifested most strongly as a substantial increase of endogenous respiration rate at night. Relief from TDS stress was incomplete when lowered pH led to a HCO3- increase (560mgC/L as a threshold). Impaired photosynthesis led to a cascade of reduced Ci-uptake, pH decrease, HCO3- accumulation, and HCO3--associated stress. Thus, long-term photobioreactor operation requires balancing the delivery rates of CO2, N, P, and other TDS components to avoid general and Ci-associated TDS stresses.
- Inorganic carbon
- Total dissolved solids
ASJC Scopus subject areas
- Environmental Engineering
- Renewable Energy, Sustainability and the Environment
- Waste Management and Disposal