In this study, considering the enhancement potential of microalgae and MBRs for wastewater treatment, the microalgae Haematococcus pluvialis, which is a freshwater species of Chlorophyta with a high ...capacity to synthesize astaxanthin, was bioaugmented into an aerobic MBR to investigate its potential on treatment of antibiotics in wastewater, reducing membrane biofouling, and impact on the microbial community structure. For this purpose, two control MBRs, with and without antibiotics, alongside an MBR bioaugmented with H. pluvialis, were set under mesophilic conditions, using inoculum from a local wastewater treatment facility and synthetic wastewater. The common antibiotics sulfamethoxazole (SMX), tetracycline (TET) and erythromycin (ERY) were selected to investigate removal efficiencies by Haematococcus pluvialis in an MBR for this study. In the bioaugmented reactor, membrane biofouling was delayed by 33% and chemical oxygen demand removal increased by 6%. The highest removal of antibiotics was observed for TET with a 20% enhancement from 69.75% (C2) to 89.73% (HP). The results also suggested that H. pluvialis reconstructed indigenous and biofilm microbial communities in MBR. The biodegradation network was modified and the relative abundance of Proteobacteria increased, while Firmicutes and Bacteroidetes were significantly reduced.
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•Microalgal addition alleviated biofouling and enhanced antibiotic removal.•Antibiotic degradation was increased by 20% for tetracycline.•Toxic effects of antibiotics on beneficial microbial community were reduced.•Algal-bacterial co-culture was established with genera Pseudomonas and Comamonas.
The olive industry extracts oil from olives but also generates solid co-products called pomace and liquid wastes known as Olive Mill Wastewater (OMW). With global annual production exceeding 30 ...million tons and approximately 685,000 tons in Morocco alone, these wastes pose environmental challenges due to their high acidity, organic load, and phenolic compounds. Our research aims to depollute and recycle OMW using aerobic biological treatment methods. Samples were collected from various ecological sites across four Moroccan regions. We isolated and purified several strains of molds, yeasts, and bacteria capable of decolorizing OMW. Decolorization experiments revealed promising results, with a combination of seven selected molds showing significant reductions in chemical oxygen demand (COD) by 71.44%, biochemical oxygen demand (BOD5) by 69.91%, and polyphenols content by 84.22%. Encouraged by these findings, we propose further treatment using sourdoughs composed of combinations of different pure strains, including yeasts and selected bacteria such as Bacillus subtilis and Pseudomonas aeruginosa. This approach demonstrates a practical and cost-effective method for depolluting and recycling OMW, contributing to environmental protection and human health preservation. By mitigating the risks associated with untreated OMW discharge, this study offers a viable solution to the environmental challenges posed by olive processing industries globally, particularly in regions like Morocco where olive cultivation is significant.
In this study, a multistage treatment system was proposed to treat real pharmaceutical wastewater containing the antibiotic amoxicillin. Ozonation (O3), and ozonation combined with aerobic ...biodegradation, were performed. The real pharmaceutical wastewater presented a high concentration of organic matter (TOC: 803 mg C·L−1 and COD: 2775 mg O2·L−1), significant amoxicillin content (50 mg L−1) and acute ecotoxicity (Aliivibrio fischeri aTU: 48.22). Ozonation proved to be effective for amoxicillin degradation (up to 99%) and the results also indicated the removal of the original colour of the wastewater, with average consumption of 1 g of ozone. However, the ozonation system alone could not achieve complete mineralization. Therefore, a combination of ozonation and biodegradation in a multistage system was proposed in order to improve cost and treatment efficiency. The multistage treatment system presented promising results, achieving degradation of more than 99% of the amoxicillin, more than 98% of the original chemical oxygen demand (COD), and 90% of initial toxicity, with the consumption of approximately 500 mg of ozone. This indicates that this system could prevent dangerous and biorecalcitrant antibiotics from entering water resources.
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•Multistage system (aerobic biological + O3) to treat real pharmaceutical effluent.•The combined treatment was able to remove >99% of the original amoxicillin content.•More than 98% of the original COD and the original colour were abated.•Moreover, more than 90% of Aliivibrio fischeri original acute toxicity was removed.
In this research, we established an enhanced aerobic biological method utilizing a high-density bacterial flora for the treatment of low-biochemical plating parts washing wastewater. The elucidation ...of pollutant removal mechanisms was achieved through a comprehensive analysis of changes in sludge characteristics and bacterial community structure. The results demonstrated that throughout the operational period, the organic load remained stable within the range of 0.01–0.02 kgCOD/kgMLSS·d, the BOD5/COD ratio increased from 0.004 mg/L to 0.33 mg/L, and the average removal rates for key pollutants, including COD, NH4+-N, and TN, reached 98.13%, 99.86%, and 98.09%. MLSS concentration remained at 7627 mg/L, indicating a high-density flora. Notably, Proteobacteria, Bacteroidota, and Acidobacteriota, which have the ability to degrade large organic molecules, had been found in the system. This study affirms the efficacy of the intensive aerobic biological method for treating low-biochemical plating washing wastewater while ensuring system stability.
•Efficient degradation of organic matter in difficult-to-biodegrade industrial wastewater by high-density colony bioprocesses.•Degradation mechanism of organic matter in electroplating wastewater degraded by high-density colony bioprocess is clarified.•Demonstration of the feasibility of biological processes for the treatment of wastewater with low biochemical properties.
Four Pilot-scale Moving Bed Biofilm Reactors (MBBRs) were operated for the treatment of real, saline, bilge wastewater. The MBBRs were connected in pairs to create two system configurations with ...different filling ratios (20%, 40%) and were operated in parallel. The inflow organic loading rate (OLR) varied from 3.6 ± 0.2 to 7.8 ± 0.6 g COD L
−1
d
−1
, salinity was >15 ppt and three hydraulic residence times (HRTs) were tested 48, 30 and 24 h. In both systems, the first-stage bioreactors (R1 and R3) eliminated the higher part of the organic load (57%-65%). The second-stage bioreactors (R2 and R4) removed an additional fraction (18%-31%) of the organic load received by the effluent of R1 and R3, respectively. The microbial communities of the influent wastewater, suspended, and attached biomass were determined using 16S rRNA gene amplicon sequencing analysis. The evolution of the microbial communities was investigated and compared over the different operational phases. The microbial communities of the biofilm presented higher diversity and greater stability in composition over time, while the suspended biomass exhibited intense and rapid changes in the dominance of genera. Proteobacteria, Bacteroidetes and Firmicutes were highly present in the biofilm. The genera Celeribacter, Novispirillum, Roseovarius (class: Alphaproteobacteria) and Formosa (class: Flavobacteriia) were highly present during all operational phases. Principal Component Analysis (PCA) was used to identify similarities between samples, exhibiting high relation of samples according to the series of the bioreactor (1st, 2nd).
The occurrence of a variety of organic pollutants has complicated wastewater treatment; thus, the search for sustainable and effective treatment technology has drawn significant attention. In recent ...years, bulk nanobubbles, which have extraordinary properties differing from those of microbubbles, including high stability and long residence times in water, large specific surface areas, high gas transfer efficiency and interface potential, and the capability to generate free radicals, have shown attractive technological advantages and promising application prospects for wastewater treatment. In this review, the basic characteristics of bulk nanobubbles are summarized in detail, and recent findings related to their implementation pathways and mechanisms in organic wastewater treatment are systematically discussed, which includes improving the air flotation process, increasing water aeration to promote aerobic biological technologies including biological activated carbon, activated sludge, and membrane bioreactors, and generating active free radicals that oxidise organic compounds. Finally, the current technological difficulties of bulk nanobubbles are analysed, and future focus areas for research on bulk nanobubble technology are also proposed.
Changes in the activated sludge performance in an anaerobic/aerobic biological treatment system for leachate was discussed under the condition of tetracycline (TC) exposure. The results show that a ...low concentration of TC did not have an obvious effect on the removal of chemical oxygen demand (COD) while a high concentration of TC had a certain promoting effect. Under the stimulation of TC, the particle size distribution of anaerobic/aerobic sludge tended to be more uniform, the particle size of anaerobic sludge decreased while the settleability increased; however, the particle size of aerobic sludge increased due to bulking. With the addition of TC, the concentration of most heavy metal ions in sludge samples increased.TC exposure results in the release of a large amount of extracellular polymeric substances (EPS), thus leading to a smoother surface of anaerobic sludge and a rougher surface of aerobic sludge. The high removal efficiency of COD under the high concentration of TC was also presumed to be due to EPS promoting the microbial absorption of anaerobic substances in the leachate. The results clearly showed that TC had a bacteriostatic effect. After antibiotic exposure, the abundance and diversity index of bacteria in each reactor decreased obviously, the microbial community evolved, and the dominant species at the genus and phylum levels of anaerobic/aerobic reactors changed. This study provides a better understanding the effect of TC on activated sludge and has reference value for the management of antibiotic exposure in leachate treatment facilities.
A multistage treatment system, at a scale close to the industrial, was designed for the treatment of a mature raw landfill leachate, including: a) an activated sludge biological oxidation (ASBO), ...under aerobic and anoxic conditions; b) a solar photo-Fenton process, enhancing the bio-treated leachate biodegradability, with and without sludge removal after acidification; and c) a final polishing step, with further ASBO.
The raw leachate was characterized by a high concentration of humic substances (HS) (1211 mg CHS/L), representing 39% of the dissolved organic carbon (DOC) content, and a high nitrogen content, mainly in the form of ammonium nitrogen (>3.8 g NH4+–N/L).
In the first biological oxidation step, a 95% removal of total nitrogen and a 39% mineralization in terms of DOC were achieved, remaining only the recalcitrant fraction, mainly attributed to HS (57% of DOC). Under aerobic conditions, the highest nitrification rate obtained was 8.2 mg NH4+–N/h/g of volatile suspended solids (VSS), and under anoxic conditions, the maximum denitrification rate obtained was 5.8 mg (NO2−–N + NO3−–N)/h/g VSS, with a C/N consumption ratio of 2.4 mg CH3OH/mg (NO2−–N + NO3−–N).
The precipitation of humic acids (37% of HS) after acidification of the bio-treated leachate corresponds to a 96% DOC abatement. The amount of UV energy and H2O2 consumption during the photo-Fenton reaction was 30% higher in the experiment without sludge removal and, consequently, the reaction velocity was 30% lower. The phototreatment process led to the depletion of HS >80%, of low-molecular-weight carboxylate anions >70% and other organic micropollutants, thus resulting in a total biodegradability increase of >70%.
The second biological oxidation allowed to obtain a final treated leachate in compliance with legal discharge limits regarding water bodies (with the exception of sulfate ions), considering the experiment without sludge.
Finally, the high efficiency of the overall treatment process was further reinforced by the total removal percentages attained for the identified organic trace contaminants (>90%).
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•Multistage treatment system for stabilized raw leachate from sanitary landfill.•Integration of biological/chemical/biological oxidations processes.•Nitrogen removal using biological nitrification and denitrification reactions.•The photo-oxidation led to the depletion of HS and other organic micropollutants.•Organic trace contaminants identification and evolution profile follow-up.
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