Phycoremediation of coastal waters contaminated with bisphenol A by green tidal algae Ulva prolifera

Mechanism of up-regulated H2O2 BPA-derived production and production of (poly)phenols by two seaweeds of the genus Ulva

The present study provides information on the effects of BPA on ROS production-related phenomena in the chlorophytes Ulva rigida and U. intestinalis, and on the mechanism they establish against BPA toxicity, at environmentally relevant concentrations (0.1-3 μg L-1). Up-regulated H2O2 generation seems to be a key factor causing oxidative damage. Interspecific differences, in terms of the mechanism and the temporal response to BPA toxicity were observed. BPA effects on U. rigida were more intense and appeared earlier (on 1D at 0.1 μg L-1) compared to U. intestinalis and mostly after 7D (LOEC: 0.3 μg L-1, Terminal time, Tt: 7D). In U. rigida, on 1-5D, the 'mosaic' type effect patterns ('models' 3A/3B) with 'unaffected' and 'affected' areas (dark content, positive H2DCF-DA staining signal/H2O2 production and chlorophyll autofluorescence signal loss) indicated a time-dependent manner. After 7D, only U. rigida cells with dark content formed aggregates, showing positive H2O2 production ('model' 4) or in some cells oxidative damages triggering retrograde signaling in the neighboring 'unaffected' areas ('model' 5). H2O2 overproduction (CTCF ratio) in U. rigida, on 1D at the lowest concentration and after 7D at 0.3-1/3 μg L-1, respectively, seems to stimulate (poly)phenolic production, in a dose- and time-dependent manner. U. intestinalis did not display severe BPA impact (i.e., 'models' 4, 5) at any exposures, although at a later time indicated a lower LOEC (0.1 μg L-1, Tt: 9D) than that in U. rigida. In U. intestinalis, H2O2 production does not appear to stimulate high (poly)phenolic amounts.

Enhanced biodegradation of 2, 4-dichlorophenol in packed bed biofilm reactor by impregnation of polyurethane foam with Fe3O4 nanoparticles: Bio-kinetics, process optimization, performance evaluation and toxicity assessment

In this work, an effort has been made to enhance the efficacy of biological process for the effective degradation of 2, 4-dichlorophenol (2, 4-DCP) from wastewater. The polyurethane foam was modified with Fe3O4 nanoparticles and combined with polyvinyl alcohol, sodium alginate, and bacterial consortium for biodegradation of 2, 4-DCP in a packed bed biofilm reactor. The maximum removal efficiency of 2, 4-DCP chemical oxygen demand, and total organic carbon were found to be 92.51 ± 0.83 %, 86.85 ± 1.32, and 91.78 ± 1.24 %, respectively, in 4 days and 100 mg L-1 of 2, 4-DCP concentration at an influent loading rate of 2 mg L-1h-1 and hydraulic retention time of 50 h. Packed bed biofilm reactor was effective for up to four cycles to remove 2, 4-DCP. Growth inhibition kinetics were evaluated using the Edward model, yielding maximum growth rate of 0.45 day-1, inhibition constant of 110.6 mg L-1, and saturation constant of 62.3 mg L-1.

Photodegradation of bisphenol A (BPA) in coastal aquaculture waters: Influencing factors, products, and pathways

Bisphenol A (BPA), an endocrine-disrupting contaminant, is ubiquitous in the environment due to its presence in plastics, wastewater, and agricultural runoff. This study investigated the photodegradation behavior of BPA in coastal aquaculture waters near Qingdao, China. Lower salinity promoted BPA photodegradation, while higher salinity has an inhibitory effect, suggesting slower degradation in seawater compared to ultrapure water. Triplet-excited dissolved organic matter (3DOM*) was identified as the primary mediator of BPA degradation, with additional contributions from hydroxyl radicals (•OH), singlet oxygen (1O2), and halogen radicals (HRS). Alepocephalidae aquaculture water exhibited the fastest degradation rate, likely due to its high DOM and nitrate/nitrite (NO3-/NO2-) content, which are sources of 3DOM* and •OH. A positive correlation existed between NO3-/NO2- concentration and the BPA degradation rate. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis identified the primary BPA photodegradation products, formed mainly through oxidative degradation, hydroxyl substitution, nitration, and chlorination pathways. Elucidating these photodegradation mechanisms provides valuable insights into the environmental fate and potential ecological risks of BPA in aquaculture environments. This knowledge can inform strategies for marine environmental protection and the development of sustainable practices.

Bisphenol A contamination in aquatic environments: a review of sources, environmental concerns, and microbial remediation

The production of polycarbonate, a high-performance transparent plastic, employs bisphenol A, which is a prominent endocrine-disrupting compound. Polycarbonates are frequently used in the manufacturing of food, bottles, storage containers for newborns, and beverage packaging materials. Global production of BPA in 2022 was estimated to be in the region of 10 million tonnes. About 65-70% of all bisphenol A is used to make polycarbonate plastics. Bisphenol A leaches from improperly disposed plastic items and enters the environment through wastewater from plastic-producing industries, contaminating, sediments, surface water, and ground water. The concentration BPA in industrial and domestic wastewater ranges from 16 to 1465 ng/L while in surface water it has been detected 170-3113 ng/L. Wastewater treatment can be highly effective at removing BPA, giving reductions of 91-98%. Regardless, the remaining 2-9% of BPA will continue through to the environment, with low levels of BPA commonly observed in surface water and sediment in the USA and Europe. The health effects of BPA have been the subject of prolonged public and scientific debate, with PubMed listing more than 17,000 scientific papers as of 2023. Bisphenol A poses environmental and health hazards in aquatic systems, affecting ecosystems and human health. While several studies have revealed its presence in aqueous streams, environmentally sound technologies should be explored for its removal from the contaminated environment. Concern is mostly related to its estrogen-like activity, although it can interact with other receptor systems as an endocrine-disrupting chemical. Present review article encompasses the updated information on sources, environmental concerns, and sustainable remediation techniques for bisphenol A removal from aquatic ecosystems, discussing gaps, constraints, and future research requirements.

Insights into effects of operating temperature on the removal of pharmaceuticals/pesticides/synthetic organic compounds by membrane bioreactor process

In this study, the removal efficiency and mechanism of 8 kinds of typical micropollutants by membrane bioreactor (MBR) at different temperatures (i.e. 15, 25 and 35 °C) were investigated. MBR exhibited the high removal rate (>85%) for 3 kinds of industrial synthetic organic micropollutants (i.e. bisphenol A (BPA), 4-tert-octylphenol (TB) and 4-n-nonylphenol (NP)) with similar functional groups, structures and high hydrophobicity (Log D > 3.2). However, the removal rates of ibuprofen (IBU), carbamazepine (CBZ) and sulfamethoxazole (SMX) with pharmaceutical activity showed great discrepancy (i.e. 93%, 14.2% and 29%, respectively), while that of pesticides (i.e. acetochlor (Ac) and 2,4-dichlorophenoxy acetic acid (2,4-D) were both lower than 10%. The results showed that the operating temperature played a significant role in microbial growth and activities. High temperature (35 °C) led to a decreased removal efficiency for most of hydrophobic organic micropollutants, and was also not conducive for refractory CBZ due to the temperature sensitivity. At lower temperature (15 °C), a large amount of exopolysaccharides and proteins were released by microorganisms, which caused the inhibited microbial activity, poor flocculation and sedimentation, resulting in the polysaccharide-type membrane fouling. It was proved that dominant microbial degradation of 61.01%-92.73% and auxiliary adsorption of 5.29%-28.30% were the main mechanisms for micropollutant removal in MBR system except for pesticides due to the toxicity. Therefore, the removal rates of most micropollutants were highest at 25 °C due to the high activity sludge so as to enhance microbial adsorption and degradation.

Enhanced degradation of bisphenol A: Influence of optimization of removal, kinetic model studies, application of machine learning and microalgae-bacteria consortia

Bisphenol A (BPA), a typical endocrine disruptor and a contaminant of emerging concern (CECs), has detrimental impacts not only on the environment and ecosystems, but also on human health. Therefore, it is essential to investigate the degrading processes of BPA in order to diminish its persistent effects on ecological environmental safety. With this objective, the present study reports on the effectiveness of biotic/abiotic factors in optimizing BPA removal and evaluates the kinetic models of the biodegradation processes. The results showed that BPA affected chlorophyll a, superoxide dismutase (SOD) and peroxidase (POD) activities, malondialdehyde (MDA) content, and photosystem intrinsic PSII efficiency (Fv/Fm) in the microalga Chlorella pyrenoidosa, which degraded 43.0 % of BPA (8.0 mg L^-1) under general experimental conditions. The bacteria consortium AEF21 could remove 55.4 % of BPA (20 mg L^-1) under orthogonal test optimization (temperature was 32 °C, pH was 8.0, inoculum was 6.0 %) and the prediction of artificial neural network (ANN) of machine learning (R² equal to 0.99 in training, test, and validation phase). The microalgae-bacteria consortia have a high removal rate of 57.5 % of BPA (20.0 mg L^-1). The kinetic study revealed that the removal processes of BPA by microalgae, bacteria, and microalgae-bacteria consortia all followed the Monod's kinetic model. This work provided a new perspective to apply artificial intelligence to predict the degradation of BPA and to understand the kinetic processes of BPA biodegradation by integrated biological approaches, as well as a novel research strategy to achieve environmental CECs elimination for long-term ecosystem health.

Bacterial degradation of bisphenol analogues: an overview

Bisphenol A (BPA) is one of the most produced synthetic monomers in the world and is widespread in the environment. BPA was replaced by bisphenol analogues (BP) because of its adverse effects on life. Bacteria can degrade BPA and other bisphenol analogues (BP), diminishing their environmental concentrations. This study aimed to summarize the knowledge and contribute to future studies. In this review, we surveyed papers on bacterial degradation of twelve different bisphenol analogues published between 1987 and June 2022. A total of 102 original papers from PubMed and Google Scholar were selected for this review. Most of the studies (94.1%, n = 96) on bacterial degradation of bisphenol analogues focused on BPA, and then on bisphenol F (BPF), and bisphenol S (BPS). The number of studies on bacterial degradation of bisphenol analogues increased more than six times from 2000 (n = 2) to 2021 (n = 13). Indigenous microorganisms and the genera Sphingomonas, Sphingobium, and Cupriavidus could degrade several BP. However, few studies focussed on Cupriavidus. The acknowledgement of various aspects of BP bacterial biodegradation is vital for choosing the most suitable microorganisms for the bioremediation of a single BP or a mixture of BP.

Enhanced removal of phenolic endocrine disrupting chemicals from coastal waters by intertidal macroalgae

The phytoremediation of phenolic endocrine disrupting compounds (EDCs) in coastal waters by intertidal macroalgae was firstly investigated. The results showed that intertidal macroalgae could remove bisphenol A (BPA) and nonylphenol (NP) at environmental relevant concentration, and Ulva pertusa was the most efficient one. In most cases, the order of EDCs removal efficiency could be expressed as: green algae > brown algae > red algae. The in-situ monitoring using a charge-coupled device imaging system confirmed the accumulation of EDCs in the intertidal macroalgae. The removal mechanisms included the initial rapid biosorption process, followed by the slow accumulation and biodegradation. The removal efficiency of BPA and NP was slightly dependent on temperature and nutrient concentration. A linear relationship was observed between the initial concentration and the average removal rate (R² > 0.99). The BPA and NP at the environmental relevant concentration (100 μg L^-1) could be removed efficiently using Ulva pertusa even after three cycles in pilot-scale experiments. The high removal efficiency of NP and BPA was also confirmed by the field investigation from the intertidal zone with abundant Ulva pertusa. These findings demonstrated that intertidal macroalgae could play essential role for the phytoremediation of phenolic EDCs in coastal waters.

Isolation of Industrial Important Bioactive Compounds from Microalgae

Microalgae are known as a rich source of bioactive compounds which exhibit different biological activities. Increased demand for sustainable biomass for production of important bioactive components with various potential especially therapeutic applications has resulted in noticeable interest in algae. Utilisation of microalgae in multiple scopes has been growing in various industries ranging from harnessing renewable energy to exploitation of high-value products. The focuses of this review are on production and the use of value-added components obtained from microalgae with current and potential application in the pharmaceutical, nutraceutical, cosmeceutical, energy and agri-food industries, as well as for bioremediation. Moreover, this work discusses the advantage, potential new beneficial strains, applications, limitations, research gaps and future prospect of microalgae in industry.

Phycoremediation coupled biomethane production employing sewage wastewater: Energy balance and feasibility analysis

In the present work Chlorella pyrenoidosa, Scenedesmus abundans and Anabaena ambigua have been evaluated for their biomass, phycoremediation efficiency and biomethane production potential by cultivating them in the primary treated sewage waste water (PTSWW) under controlled conditions. By the end of 25-day experiment, up to 52-88% reduction was observed in the nutrient concentration from the 3:1 ratio of PTSWW. Co-digestion of microalgal biomass (dry) with cow dung was performed to estimate biomethane potential. Biogas yield of 618-925 ml g^-1 VS with 48-65% of methane content was obtained employing the microalgal species cultivated in PTSWW. Microalgae appeared notably competent at nutrient sequestration from PTSWW with significant microalgal biomass productivity for biogas production. Energy balance studies revealed the feasibility of coupling the remediation with energy generation. High photosynthetic rate and biomass generation ability along with nutrient confiscation supports employment of microalgae as a potential next generation biofuel source with waste management.

One-pot synthesis of magnetic algal carbon/sulfidated nanoscale zerovalent iron composites for removal of bromated disinfection by-product

Magnetic algal carbon supported flower-like sulfidated nanoscale zerovalent iron (S-nZVI/AC) composite was firstly synthesized through one-pot method and used for removing bromate. More than 98% of bromate was efficiently removed within 48 min. Compared with the individual S-nZVI treatment, the removal rate constant of the S-nZVI/AC composite treatment was almost doubled. The removal rate constant of bromate increased three times when the S/Fe ratio increased from 0 to 0.3. According to the synergistic effect between the algal carbon and S-nZVI on the bromate removal, the introduction of carbon and sulfide-modification of nZVI were efficient modification approaches for enhancing the removal of bromated using S-nZVI/AC composite. The removal efficiency of bromate increased sharply to more than 98% when the composite dose increased from 0 to 40 mg L^-1. The removal rate constant increased linearly from 0.08 to 0.31 min^-1 when the initial concentration increased from 50 to 200 μg L^-1. The removal efficiency of the bromate still maintained at high level (>85%) after 5 recycles of the S-nZVI/AC composite. Bromate was readily removed under neutral or slight acidic conditions. The bromate removal rate constant increased from 0.10 to 0.27 min^-1 when the temperature increased from 15 to 35 °C. The bromate removal rate constant increased almost 4 times when the ionic strength increased from 0 to 3 g L^-1. This study demonstrates that S-nZVI/AC composite synthesized through one-pot method is a promising water purification material for efficient removal of bromated disinfection by-product.

One-step green preparation of magnetic seaweed biochar/sulfidated Fe0 composite with strengthen adsorptive removal of tetrabromobisphenol A through in situ reduction

Rare information is available on the facile preparation of biochar/sulfidated Fe⁰ composite. A facile one-step green method was established for the synthesis of magnetic seaweed (Ulva prolifera) biochar/sulfidated Fe⁰ composite (S-Fe⁰/BC) to use excessive seaweed biomass. Removal efficiency of tetrabromobisphenol A (TBBPA) reached up to 88% in iron-sulfur treatment. Two major products were identified as bisphenol A and monobromobisphenol A, confirming the in-situ reductive debromination of TBBPA. Batch experiments showed that the removal of TBBPA was facilitated with S/Fe molar ratio of 0.2 and acidic conditions (pH = 3-7). The S-Fe⁰/BC composite had good stability and reusability based on the cycle experiments. The removal process of TBBPA by S-Fe⁰/BC composite might include chemical adsorption by S-Fe⁰/BC composite, reduction debromination by S-Fe⁰ and enhanced electron transfer. The environmentally-friendly S-Fe⁰/BC composite synthesized by one-step facile procedure showed novel potential applications in terms of pollution control of halogenated xenobiotic compounds such as TBBPA.

An integrated approach for tannery effluent treatment with ozonation and phycoremediation: A feasibility study

For the exploration of an effective and economical method to treat composite raw tannery effluent, the integrated approach of Ozonation and phycoremediation was followed. In a lab-scale Ozone reactor, the highest performance index was attained, when it was operated at a low O₃ flowrate (2 g/h) condition. The tannery effluent partially treated by Ozonation (≈60% COD removed in 90 min) with the ozone consumption of 1.5 g of O₃/g of COD, at pH 7.6, coupled with phycoremediation had improved the tannery effluent characteristics to a considerable extent. Overall, the maximum reduction in pollutant concentration attained with the combined treatment was 84% for COD, 60% for colour, 100% for odour, 90% for inorganic carbon, 82% for NH₄⁺- N, 100% for PO₄-P, 97% for chromium and 10% for TDS. In phycoremediation, microalgae Nannochloropsis oculata had shown an enhanced growth (μ = 0.255 day^-1) with a maximum cell density of 5.2 × 10⁷ cells/mL, dry biomass of 0.86 g L^-1 and cell division rate of 0.369 day^-1. Elemental analysis of biomass validated the chromium remediation along with other elements such as calcium, magnesium, sodium, potassium, zinc, and iron from the tannery effluent. Therefore, the phycoremediation integrated ozone process can be considered as a feasible treatment method for tannery effluent along with value-added biomass production.

Phycoremediation potential of microalgae species for ethidium bromide removal from aqueous media

Ethidium Bromide (EtBr) is an organic compound used in molecular biology investigations. EtBr ability of intercalating in the DNA molecule makes it a toxic substance. The objective was to evaluate the phycoremediation potentials of Chlorella vulgaris, Desmodesmus subspicatus and Raphidocelis subcapitata tested separately and in a mixture (Mix) for EtBr removal from the aqueous medium. Experiments were conducted using an initial algae biomass of 10⁶ cell/mL, exposed to 500 µg/L of EtBr. The removal efficiency (µg EtBr L^-1) after 3 h in each treatment were: Mix (72.8 µg.L^-1) >D. subspicatus (48.4 µg.L^-1) >R. subcapitata (24.6 µg.L^-1) >C. vulgaris (19.9 µg.L^-1). However, when EtBr mass reduction per microalgae density is considered (ng.algae^-1), the efficiency ranking changes to: D. subspicatus (1.9 × 10^-5ng.algae^-1) >C. vulgaris (1.4 × 10^-5ng.algae^-1) >Mix (9.8 × 10^-6ng.algae^-1) >R. subcapitata (2.8 × 10^-6ng.algae^-1). The results suggest that initial algal population density is a determinant factor for efficient EtBr removal by microalgae species in short term treatments. In order to obtain 100% of EtBr removal, it should be necessary 10¹⁰, 10¹⁰ and 10¹¹ algae.mL^-1 of C. vulgaris, D. subspicatus and R. subcapitata, respectively. The results strongly suggest phycoremediation can be explored as an alternative method for EtBr removal.

Ulva lactuca, A Source of Troubles and Potential Riches

Ulva lactuca is a green macro alga involved in devastating green tides observed worldwide. These green tides or blooms are a consequence of human activities. Ulva blooms occur mainly in shallow waters and the decomposition of this alga can produce dangerous vapors. Ulva lactuca is a species usually resembling lettuce, but genetic analyses demonstrated that other green algae with tubular phenotypes were U. lactuca clades although previously described as different species or even genera. The capacity for U. lactuca to adopt different phenotypes can be due to environment parameters, such as the degree of water salinity or symbiosis with bacteria. No efficient ways have been discovered to control these green tides, but the Mediterranean seas appear to be protected from blooms, which disappear rapidly in springtime. Ulva contains commercially valuable components, such as bioactive compounds, food or biofuel. The biomass due to this alga collected on beaches every year is beginning to be valorized to produce valuable compounds. This review describes different processes and strategies developed to extract these different valuable components.