BACKGROUND Owing to their complexity a lot of research is performed on micro‐algal systems for wastewater treatment. In this work a previously developed combined respirometric–titrimetric approach was used for the determination of micro‐algal kinetics. A Plackett–Burman design with fold‐over was executed to investigate the influence of eight different degrees of freedom regarding environmental conditions on five different aspects (or responses) related to the micro‐algal photosynthetic activity. RESULTS Results revealed correlation between micro‐algal biomass concentration and both oxygen production rate and proton addition rate. When ammonium limiting conditions were implemented (molar N/P ratio = 7/1), a decrease of the titrimetric profile was observed. Regarding light intensity and temperature, no limitation was observed. Furthermore, with respect to inorganic phosphorus, no limitation was observed. CONCLUSIONS Although expected based on the literature, limitation was not observed for light intensity, temperature, and inorganic phosphorus, indicating that these state conditions were not limiting in the ranges applied in this research. Overall it can be concluded that the combined respirometric–titrimetric approach is successful for determination of limiting and non‐limiting components of wastewater nutrients and environmental conditions for micro‐algal growth. © 2014 Society of Chemical Industry