Page 208 - Industrial Wastewater Treatment, Recycling and Reuse

182 Industrial Wastewater Treatment, Recycling, and Reuse

3.6.2 Biodegradability Enhancement of Distillery Wastewater
Using HC

Distilleries are considered as one of the most highly polluting industries
worldwide. The wastewater generated from a distillery unit is dark brown
in color and contains very high biological oxygen demand (BOD: 50,000–
60,000 ppm), chemical oxygen demand (COD: 110,000–190,000 ppm),
and high BOD/COD ratio in the range of 0.3–0.6. The amount of inor-
ganic substances such as nitrogen, potassium, phosphates, calcium, and sul-
fates is also very high. Even after the conventional anaerobic digestion, the
biomethanated distillery wastewater (B-DWW) still retains around
40,000 mg/L of COD and significant color and becomes recalcitrant (BI:
BOD 5 /COD 0.14) to further treatment by conventional biological
methods. With more stringent rules and regulations imposed by government,
distillery industries have been forced to look for more effective treatment
technologies. Such technologies would be beneficial to the environment,
but also needs to be cost effective. This problem has emphasized the need for
further research on developing effective treatment/pretreatment methods
for safe disposal of anaerobically digested distillery wastewater.
Padoley et al. (2012) reported the use of HC as a pretreatment option for
the complex/recalcitrant B-DWW. The effect of various process parameters
such as inlet pressure, dilution, and reaction time on reduction of COD/
TOC and enhancement in the biodegradability index (BI: BOD 5 :COD
ratio) of the B-DWW has been reported with an aim of maximizing the bio-
degradability index and achieving lower toxicity of the distillery wastewater.
To check the efficacy of HC in treating such effluents, distillery wastewater
treated in a conventional anaerobic digester from a distillery near Nagpur,
India (source not given due to confidentiality issues), was used for the
studies. The physicochemical properties of this waste are given in Table 3.2.

Table 3.2 Characteristics of complex wastewater (biomethanated distillery wastewater)
Parameters Value
pH 7.61
Color Brown
COD (mg/L) 35,000
BOD (mg/L) 5000
TOC (mg/L) 10,000
Total solids (mg/L) 31,000
Total suspended solids (mg/L) 1600
Biomass (%) 1
BOD:COD ratio 0.168