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15 Photobiological Reactors for the Degradation of Harmful Compounds in Wastewaters

Photobiological reactors

Microbes as

photo-bio

agents

Photolytic and

photochemical

methods

Membrane-based

techniques

Nano

technology

approaches

Aspergilus

niger {immobilized}

Alkane degrading

bacteria

Oil degrading bacteria

Photo-enhanced

degradation

Photo-activated

(chemical) degradation

Photocatalytic

degradation

Photo-fermentation

Peppermild mottle

virus {plant pathogen}

Cyanobacteria

Yeast

Algae bacteria

Photosynthetic and

acidogenic bacteria

Halomonas species

{anaerobic}

Figure 15.3

Various photobiological agents used in photobiological reactors for treating

wastewater.

as photo-Fenton catalysts for the exclusion of bacteria in secondary wastes. Similar

residence times and a 5-log removal of naturally occurring fecal bacteria from an

activated sludge effluent were obtained. This allows designing, studying, and further

expanding the use of FeOx as effective photo-Fenton catalysts, even for wastewater

matrices. In order to clarify the high efficiency, the inactivation mechanism was fur-

ther studied. Among the concerned processes, the removal of bacteria by adsorption

process, semiconductor action mode, and the homogeneous photo-Fenton process

were found to be less prevalent. The heterogeneous photo-Fenton is the key process

and the heavy force of inactivation. The adsorption is not high due to the compe-

tition of dissolved organic matter (DOM) with bacteria. The carbonate content of

wastewater can play a distinct role in hindering the inactivation process, while the

DOM can also be a competitor for the oxidative actions.