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Reorienting Waste Remediation Towards Harnessing Bioenergy 257

conditions at the cathode, different compounds can be synthesized; there-
fore, the MFC can also be used for product recovery in addition to treatment
unit functionality. Bio or microbial electrosynthesis is a process that involves
microbially catalyzed synthesis of chemical compounds in an electrochem-
ical cell (Rabaey and Rozendal, 2010). The term microbial electrosynthesis has
recently been used for the electrically driven reduction of carbon dioxide
(Nevin et al., 2010). In recent times, considerable interest has been centered
on the application of a biocathode in combination with a catalyzed cathode
for bioelectrosynthesis (Rozendal et al., 2006). With the aid of a small input
of electric power, many value-added compounds are formed at the cathode.

6.5 BIOPLASTICS

Majority of plastics are based on fossil fuels that are durable and degrade
slowly and upon incineration they release gaseous pollutants ( Jin et al.,
2013). In this area of interest, bioplastics such as polyhydroxyalkanoates
(PHAs) have attracted great interest due to their biodegradable nature
(Liu et al., 2011). PHAs (mass of 50–100 kDa) are synthesized by bacteria
from renewable resources produced as cellular reserve storage products
under excess carbon and nutrient-deprived conditions (Madsen, 2008;
Steinbu ¨chel, 1992). The most common type of PHA is polyhydroxybuty-
rate (PHB). PHAs have special physical traits, such as elasticity, a high crys-
tallization rate, and a high degree of polymerization (Madsen, 2008; Satoh
et al., 1999). They can be converted to a wide range of finished products for
application in industry, agriculture, and medicine (Akaraonye et al., 2010).
Major drawbacks for their commercialization are the high production costs
in which feedstock accounts for 50% of the overall price (Choi and Lee,
1999). Hence, there is a need for cheap renewable resources, wherein waste-
water fits well.

6.5.1 Bioplastics Synthesis from Wastewater
Wastewater contains different types of organic compounds. After hydrolysis
these complex organic compounds are degraded into simple sugars
(Figure 6.6). These simple sugars through glycolysis are converted into VFAs
(acetate, propionate, butyrate, and valerate) (Anderson and Dawes, 1990;
Dawes, 1986). VFAs are the key precursors for PHA production. VFAs gen-
erated during fermentation are transported across the cell membrane and
then activated to the corresponding acyl-CoA. Bacteria are cultivated on car-
bohydrates, pyruvate, or acetate, and the PHA is synthesized in a three-step