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15 Photobiological Reactors for the Degradation of Harmful Compounds in Wastewaters

which improve the removal of nutrients, heavy metals, and organic pollutants

efficiently from diverse wastewaters. Recent studies have shown that PSB-based

technologies are having great predictions and economic effects. The mode of PSB

biodegradation processes presented a promising alternative for new wastewater

treatment scheme. The varied metabolism of PSB awards them with influential

adaptability, and in particular, photosynthesis under photo-anaerobic condition

disrupts the carbon cycle in the CAS. The entire process decreases CO2 and builds

nutrients from wastewater, which accords with the model shift of wastewater

treatment from pollution elimination to nutrient and energy recovery. Currently,

PSB-based technology for wastewater treatment emphasizes on bio-transformation

of nontoxic wastewater and bioresource recovery. In addition, the degradation

outcome of PSB on some hazardous or refractory contaminants is considerable

and the possibility of trial operations has been sufficiently demonstrated, but

much of the investigation is currently limited to the laboratory or small pilot scale.

Recent study shows relatively slow growth rate (five to seven days), unstable COD

removal rate (30–99%), and energy input cost. Process parameter control, proper

pretreatment, and posttreatment are required to meet the current water treatment

discharge standards. Research in the following aspects is still at the initial stage.

●Selection of more effective strains capable to grow under wider and more extreme

conditions

●In-depth mechanisms, models, and key parameters for better industrialized appli-

cations

●Development and optimization of more photo-reactors for improving biomass

control and light conversion efficiency [16]

15.2.1.15

Anaerobic Fermentation for the Production of Short-Chain Fatty

Acids by Acidogenic Bacteria

The nonylphenol (NP) biodegradation under anaerobic conditions is problematic.

Here, anaerobic NP biodegradation by acidogenic bacteria through anaerobic fer-

mentation of waste activated sludge (WAS) for short-chain fatty acid (SCFA) produc-

tion is stated. The extreme squalor efficiency of NP (69.4%) was attained at pH 10.0

and 10 mg/l Brij 35 within eight days, which was nearly threefold of that in the

control (24.6%). Examination of mechanism exposed that the bioavailability of NP,

specific NP-degrading bacteria, and their useful genes were helpful for NP biodegra-

dation with surfactant at alkaline pH. More prominently, acidogenic bacteria, the

leading functional bacteria in WAS fermentation systems, were established to be

complicated in NP anaerobic biodegradation by providing intermediate organic sub-

strates and intrinsic NP-degrading aptitudes. During anaerobic fermentation of WAS

for SCFAs production, NP biodegradation was enhanced at alkaline pH with surfac-

tant addition. The acidogenic bacteria, which possess outstanding ability to degrade

NP and have enough organic substrates for co-metabolism, were of great support for

NP biodegradation [17].