Ozonation and UV254 nm radiation for the removal of microorganisms and antibiotic resistance genes from urban wastewater

An overview of graphene materials: Properties, applications and toxicity on aquatic environments.

The effects of groundwater and surface water constituents (i.e., natural organic matter [NOM] and the presence of a complex assortment of ions) on graphene oxide nanoparticles (GONPs) were investigated to provide additional insight into the factors contributing to fate and the mechanisms involved in their transport in soil, groundwater, and surface water environments. The stability and transport of GONPs was investigated using dynamic light scattering, electrokinetic characterization, and packed bed column experiments. Stability results showed that the hydrodynamic diameter of the GONPs at a similar ionic strength (2.1±1.1 mM) was 10 times greater in groundwater environments compared with surface water and NaCl and MgCl2 suspensions. Transport results confirmed that in groundwater, GONPs are less stable and are more likely to be removed during transport in porous media. In surface water and MgCl2 and NaCl suspensions, the relative recovery was 94%±3% indicating that GONPs will be very mobile in s...

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Stability and transport of graphene oxide nanoparticles in groundwater and surface water

Soft templated mesoporous carbons : tuning the porosity for the adsorption of large organic pollutants

Unary and binary adsorption studies of lead and malachite green onto a nanomagnetic copper ferrite/drumstick pod biomass composite.

Humic acids (HAs) content of raw water is an important analytical parameter in water treatment facilities because HAs in the presence of chlorine may lead to the formation of dangerous by-products (e.g., trihalomethanes). The concentration of HAs in water is not directly accessible by common analytical methods due to their heterogeneous chemical structure. The aim of this study was to compare two methods to assess humic acids (HAs) in surface water namely absorbance of ultraviolet light at 254 nm (UV254) and total organic carbon (TOC), as well as to evaluate the effects of calcium and magnesium concentrations, pH and sample filtration on the methods' results. An aqueous solution of a commercial HA with 10 mg L−1 was used in the present work. Quantification of the HA was carried out by both UV254 and TOC (combustion-infrared method) measurements. UV254 results were converted to TOC using a calibration curve. The effects of calcium (0–136.3 mg L−1) and magnesium (0–34.5 mg L−1) concentrations, pH (4.0, 7.0 and 9.0) and sample filtration on UV254 and TOC measurements of the HA suspension were evaluated. More accurate TOC values of HA suspensions were obtained by the combustion-infrared method than by the UV254 absorbance method. The higher differences of TOC values between unfiltered and filtered samples were detected in the presence of calcium at pH 9.0 using the spectrophotometric method.

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Quantification of humic acids in surface water: effects of divalent cations, pH, and filtration.

https://repositorium.sdum.uminho.pt/bitstream/1822/11209/1/Rodrigues_Bioresource%20Technology.pdf

Biofilms formed on humic substances: Response to flow conditions and carbon concentrations

A very compact flat microbial fuel cell (MFC), with 64 cm2 each for the anode surface and the cathode surface and 1 cm3 each for the anode and cathode chambers, was tested for wastewater treatment with simultaneous electricity production with the ultimate goal of implementing an autonomous service in decentralized wastewater treatment systems. The MFC was operated with municipal wastewater in sequencing batch reactor mode with re-circulation. Current densities up to 407 W/m3 and a carbon removal of 83% were obtained. Interruption in the operation slightly decreased power density, while the re-circulation ratio did not influence power generation. The anode biofilm presented high conductivity, activity and diversity. The denaturing gradient gel electrophoresis band-pattern of the DNA showed the presence of several ribotypes with different species of Shewanellaceae and Geobacteraceae families.

A flat microbial fuel cell for decentralized wastewater valorization: process performance and optimization potential

Biofilms are major sites of carbon cycling in streams. Therefore, it is crucial to improve knowledge about biofilms' structure and microbial composition to understand their contribution in the self-purification of surface water. The present work intends to study biofilm formation in the presence of humic substances (HSs) as a carbon source. Two biofilm flowcells were operated in parallel; one with synthetic stream water, displaying a background carbon concentration of 1.26+/-0.84 mg L(-1), the other with added HSs and an overall carbon concentration of 9.68+/-1.00 mg L(-1). From the biofilms' results of culturable and total countable cells, it can be concluded that the presence of HSs did not significantly enhance the biofilm cell density. However, the biofilm formed in the presence of HSs presented slightly higher values of volatile suspended solids (VSS) and protein. One possible explanation for this result is that HSs adsorbed to the polymeric matrix of the biofilm and were included in the quantification of VSS and protein. The microbial composition of the biofilm with addition of HSs was characterized by the presence of bacteria belonging to beta-Proteobacteria, Cupriavidus metallidurans and several species of the genus Ralstonia were identified, and gamma-Proteobacteria, represented by Escherichia coli. In the biofilm formed without HSs addition beta-Proteobacteria, represented by the species Variovorax paradoxus, and bacteria belonging to the group Bacteroidetes were detected. In conclusion, the presence of HSs did not significantly enhance biofilm cell density but influenced the bacterial diversity in the biofilm.

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Characterization of biofilm formation on a humic material

Nitrate removal from water has been accomplished by heterotrophic biofilms using organic carbon as a source of reducing power. To overcome the natural limitation in organic carbon in water, a poly-e-caprolactone based biofilm carrier that serves simultaneously as a biofilm carrier and as a source of organic carbon was developed and tested in the present work. The feasibility of the new biofilm carrier for nitrate removal from water was evaluated in a packed bed reactor. The combination of size and structure provided a carrier element having high surface area and void volume, 1,170 m2/m3 and 67 %, respectively. A maximum denitrification rate of 4.4 mg N–NO3
 −/(L.h) (9.2 mg N–NO3
 −/(m2.h)) was achieved in the packed bed reactor at 20 °C and pH 7.0. Main advantages of the biofilm carrier developed in the present work are its mechanical stability in water even after biofilm formation and controlled release of organic carbon by enzymatic reactions. The proposed biotechnology to remove nitrate from groundwater is robust and easy to operate.

/pdf/a-poly-epsilon-caprolactone-based-biofilm-carrier-for-3412jwtwv8.pdf

A. L. Rodrigues

Papers

Quantification of humic acids in surface water: effects of divalent cations, pH, and filtration.

Biofilms formed on humic substances: Response to flow conditions and carbon concentrations

A flat microbial fuel cell for decentralized wastewater valorization: process performance and optimization potential

Characterization of biofilm formation on a humic material

A poly-epsilon-caprolactone based biofilm carrier for nitrate removal from water