The growth of Scenedesmus quadricauda in RO concentrate and the impacts on refractory organic matter, Escherichia coli, and trace organic compounds

Abstract

This study achieves a better operational simplicity for the phycoremediation of reverse osmosis (RO) concentrate using Scenedesmus quadricauda microalgae. Under continuous illumination with CO supplementation, algal growth in the RO concentrate resulted in a conversion of polymeric organic matter (a mixture of humic substances and polysaccharides) to biodegradable fractions and their prompt removal along with inorganic nutrients (NO and PO). The algal-induced degradation of humic-like substances which are typically refractory to microbial decomposition was demonstrated in an indirect manner. In this study, we also investigated the effects of algal treatment on the growth of Escherichia coli and removal of trace organic compounds (TOrCs) from the RO concentrate. Our results indicate that algal treatment of the RO concentrate using aeration with 10% (v/v) CO under continuous illumination is highly feasible as a safe and inexpensive technology to remove non- or slowly-biodegradable organic matter, reduce enteric bacteria, and attenuate TOrCs in wastewater. However, the results should not be generalized, but critically discussed, due to limitations of using the synthetic RO concentrate in evaluating the performance of wastewater remediation with microalgae.

Effects of Propranolol on Growth, Lipids and Energy Metabolism and Oxidative Stress Response of Phaeodactylum tricornutum

“…Previous reports indicated that, in some conditions, the energy can be diverted from the ETC to the cleavage of benzenic skeletons, such as those found in propranolol structure [ 37 ]. In this case, cells undergo a shift from autotrophic to mixotrophic [ 75 , 76 , 77 ]. As already referred, in the present work, the photochemical energy trapping shows a severe depletion in favor of the increase in energy dissipation and thus, cells were unable to use this potentially diverted energy and propranolol as a substrate for cell growth, as observed in P. tricornutum cells exposed to bezafibrate [ 37 ].…”

A proof of concept study for wastewater reuse using bioelectrochemical processes combined with complementary post-treatment technologies

“…quadricauda removed carbamazepine by 1.9±0.5 μg L −1 (24±6%) for 36 h of cultivation under the given conditions, which was consistent with our previous observations. 18 Carbamazepine is known to be recalcitrant toward biodegradation, correlated to the nonpolar hydrophobicity of the compound. Considering its high log K ow value of 2.25 (octanol/ water partition coefficient), 16 hydrophobic sorption is proposed as the dominant mechanism for the removal of carbamazepine by microalgae.…”

“…Carbamazepine is hardly removed by biological activities during slow bio-filtration, 3,16 bioelectrochemical treatment, 17 or algal treatment. 18 Carbamazepine, diclofenac, clofibric acid, and gembrozil are known to be recalcitrant toward biodegradation in the nitrification/denitrification of wastewater, 19,20 and among these, carbamazepine requires the highest UVC dose to be degraded by > 90%. 21 In this study, carbamazepine was used as an effectiveness indicator of oxidation capacity in AOPs using UVC/H 2 O 2 .…”

Enhanced Reverse Osmosis Concentrate Disposal and Nutrients Conversion to Microalgae Bioenergy with a Gradient-Fed Strategy

“…In contrast, using microalgae to treat ROC can cause an uptake of nutrients from ROC to produce bioproducts (lipids, carbohydrates, and protein) via photosynthesis, simultaneously realizing ROC disposal and nutrients recycling for bioenergy generation. − Recent research studies have verified the feasibility of wastewater treatment with microalgae for nutrients recovery. But the growth profiles of microalgae in raw wastewater were poor, which were attributed to the strong toxicity of the wastewater .…”