Influence of hydraulic retention time and carbon loading rate on the production of algae

Abstract

This paper is focused on the assessment of the production of algae in batch bioreactors. Hydraulic retention time, carbon loading rate and light color were the inputs of the study and algae production the main output. Bioreactors were operated in semi-continuous mode and tests lasted two months, more than two times the period required to meet a steady-state response. This steady-state was verified with plateau responses in both, soluble parameters and suspended solids. Results points out the great relevance of temperature. Likewise, they show that green light improves the production of algae, as well as long HRT and high CLR. Maximum production rates attained were in the range 4-14 mg d L. The ratio COD /TSS for this biofuel was almost constant (3.13 mg COD mg TSS) but the quality of the product obtained in terms of the Mean Oxidation State of Carbon is completely different. Longer HRT leads to lower MOSC and hence to potentially more valuable fuels.

The Algicidal Potential of a Floating-Bed System against Microcystis aeruginosa in Laboratory Conditions

“…After the formation and domestication of the biological membrane in the system, the effects of pH values (pH = 5, 6, 7, 8, 9), dissolved oxygen levels (DO = 2, 3, 4, 5, 6 mg/L), hydraulic retention time (12,24,36,48, 60 h), and temperature (15,20,25,30 • C) on the algae's removal efficiency were investigated, with a chlorophyll concentration of 143.79-148.87 µg/(L•d). Furthermore, dehydrogenase activity, soluble protein, and malondialdehyde content were determined using the optimal factors under the aforementioned conditions (shown in Tables S1-S5).…”

“…This finding aligns with the research conducted by Solmaz [35] et al They discovered that shorter HRT and higher flow rates can promote the growth of algae, resulting in increased chlorophyll-a content. The potential underlying reason for this phenomenon is that as the reaction time extends, the nutrients in the water gradually deplete, and the flow carries away the accumulated nutrients in the cells of algae [36]. This flushing effect greatly reduces the possibility of nutrient overload in the water, thereby improving the self-purification capacity of the continuous-flow water system.…”