Predatory bacteria in combination with solar disinfection and solar photocatalysis for the treatment of rainwater

Abstract

The predatory bacterium, Bdellovibrio bacteriovorus, was applied as a biological pre-treatment to solar disinfection and solar photocatalytic disinfection for rainwater treatment. The photocatalyst used was immobilised titanium-dioxide reduced graphene oxide. The pre-treatment followed by solar photocatalysis for 120 min under natural sunlight reduced the viable counts of Klebsiella pneumoniae from 2.00 × 10 9 colony forming units (CFU)/mL to below the detection limit (BDL) (<1 CFU/100 µL). Correspondingly, ethidium monoazide bromide quantitative PCR analysis indicated a high total log reduction in K. pneumoniae gene copies (GC)/mL (5.85 logs after solar photocatalysis for 240 min). In contrast, solar disinfection and solar photocatalysis without the biological pre-treatment were more effective for Enterococcus faecium disinfection as the viable counts of E. faecium were reduced by 8.00 logs (from 1.00 × 10 8 CFU/mL to BDL) and the gene copies were reduced by ~3.39 logs (from 2.09 × 10 6 GC/mL to ~9.00 × 10 2 GC/mL) after 240 min of treatment. Predatory bacteria can be applied as a pre-treatment to solar disinfection and solar photocatalytic treatment to enhance the removal efficiency of Gram-negative bacteria, which is crucial for the development of a targeted water treatment approach.

A Review of Photoelectrocatalytic Reactors for Water and Wastewater Treatment

“…Post-treatment filtration is still required to separate the photocatalyst from the solution, and cost/energy analysis also needs to be performed to examine if the additional complexity and input energy are worth the increased efficiency. To remove the need for filtration, the photocatalyst can be immobilised onto millimeter-scale substrates, i.e., beads or Raschig rings [108], to be used as the 3D electrode, as in the design of Liu et al [106] shown in Figure 26. Their system used Fe2O3/graphite and TiO2-coated glass beads as the 3D electrode.…”

“…The inclusion of the 3D electrode improved the rate of berberine chloride form degradation, and a rate constant (k) of 0.015 min −1 was achieved with the 3D electrode under irradiation, compared to k = 0.007 min −1 without irradiation and k = 0.001 min −1 without irradiation and the 3D electrode. The efficiency analysis shows that the 3D electrode had a higher mineralisation To remove the need for filtration, the photocatalyst can be immobilised onto millimeterscale substrates, i.e., beads or Raschig rings [108], to be used as the 3D electrode, as in the design of Liu et al [106] shown in Figure 26.…”

Employing speciation of metals to assess photo-assisted electrochemical efficiency for improving rainwater quality in Tehran, Iran

“…Previous literature has mainly focused on oxidizing various contaminants in rainwater purification using PC (Ab Aziz et al 2018;Nwoke et al 2018;Waso et al 2020). However, only a few studies have been carried out using PEC for rainwater treatment.…”

Visible‐Light‐Driven Photocatalysis‐Enhanced Nanozyme of TiO2 Nanotubes@MoS2 Nanoflowers for Efficient Wound Healing Infected with Multidrug‐Resistant Bacteria

“…[19,20] The photoactivated strategies such as photodynamic therapy, photothermal therapy or photocatalysis could also possess antimicrobial ability. [21] Especially, the photocatalysis could combat the bacterial through the ROS including hydroxyl radical (•OH) and superoxide radical (O 2 •−…”