1 Introduction
Industrial waste management is the major thrust area of research in the world, as
these wastes contain a variety of organic and inorganic pollutants that cause serious
environmental pollution and toxicity in living beings (Goutam et al. 2018;
Bharagava et al. 2017a, b; Chandra and Kumar 2015a). The discharge of waste
(solid and liquid) into the environment from distilleries is a threat to the ecosystem
due to the big environmental hassle (Chandra and Kumar 2017a, b, Chowdhary et al.
2017). In India, distilleries are one of the major agro-based polluting industries; in
addition, they are a high consumer of raw water, utilizing the molasses from cane
sugar manufacturing (sugar mills) as the starting material for ethanol production.
Molasses (a by-product of the sugar industry) contains roughly 50% fermentable
sugars (glucose, fructose, and sucrose). In distilleries, during the ethanol production,
a major portion (approximately 90%) of the fermented wash going to distillation
column is discharged as wastewater named vinasses or spent wash (SW) or raw
effluent (Chandra and Kumar 2017b). The characteristic of the SW varies and
depends on the fermentation feedstock and fermentation and distillation processes
adopted in distilleries. The molasses-based distilleries are mainly located in subtropical and tropical regions of the world, and these generate approximately 12–15 liters
of SW per liter of ethanol production (Chandra et al. 2018a; Chandra and Kumar
2017b). The SW is characterized with unpleasant odor; dark-brown color; high level
of total dissolved solids (TDS); chemical oxygen demand (COD); biological oxygen
demand (BOD); total Kjeldahl nitrogen (TKN), sulfide (SO 3
2À
), sodium (Na
+
), and
phosphate (PO 4
3À ); and the presence of various toxic heavy metals (HMs), viz., iron
(Fe), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), and manganese (Mn), and
nitrogen-containing complex organic pollutants and endocrine-disrupting chemicals
(EDCs) with low pH (Kaushik and Thakur 2013; Chandra and Kumar 2017b). The
origin of dark-brown color in SW is primarily associated with the low and high
molecular weight (mw) melanoidin pigments, a class of compounds known as
Maillard reaction products (MRPs) (Arimi et al. 2014). Currently, in India, there
are 397 distilleries that are producing approximately 3.25 Â 10
10 liters of ethanol and
generating approximately 40.90 Â 10
15 liters of SW per annum (Kumar and Chandra
2018). Due to high pollution nature of SW, the Ministry of Environment, Forest, and
Climate Change, Govt. of India, has listed ethanol industries at the top among the
“Red category” industries (Tewari et al. 2007). Regarding water and soil pollution,
the Bureau of Indian Standard (BIS) provides guidelines to the central and state
government authorities which would help to decide suitable restrictions on effluent
disposal and to the industry for selecting a suitable site and suitable treatment
technology for effluents prior to their disposal into the environment. Consequently,
distillery effluent must be properly treated before it is discharged into the environment (Tewari et al. 2007). In industry, distillery SW treatment is being carried out
commonly by four routes: (i) concentrate the SW followed by incineration, (ii) direct
oxidation of SW by air (oxygen) at a high temperature followed by aerobic treatment, (iii) anaerobic treatment (methanogenesis) of SW with methane (biogas)
496
V. Kumar and R. Chandra
Industrial waste management is the major thrust area of research in the world, as
these wastes contain a variety of organic and inorganic pollutants that cause serious
environmental pollution and toxicity in living beings (Goutam et al. 2018;
Bharagava et al. 2017a, b; Chandra and Kumar 2015a). The discharge of waste
(solid and liquid) into the environment from distilleries is a threat to the ecosystem
due to the big environmental hassle (Chandra and Kumar 2017a, b, Chowdhary et al.
2017). In India, distilleries are one of the major agro-based polluting industries; in
addition, they are a high consumer of raw water, utilizing the molasses from cane
sugar manufacturing (sugar mills) as the starting material for ethanol production.
Molasses (a by-product of the sugar industry) contains roughly 50% fermentable
sugars (glucose, fructose, and sucrose). In distilleries, during the ethanol production,
a major portion (approximately 90%) of the fermented wash going to distillation
column is discharged as wastewater named vinasses or spent wash (SW) or raw
effluent (Chandra and Kumar 2017b). The characteristic of the SW varies and
depends on the fermentation feedstock and fermentation and distillation processes
adopted in distilleries. The molasses-based distilleries are mainly located in subtropical and tropical regions of the world, and these generate approximately 12–15 liters
of SW per liter of ethanol production (Chandra et al. 2018a; Chandra and Kumar
2017b). The SW is characterized with unpleasant odor; dark-brown color; high level
of total dissolved solids (TDS); chemical oxygen demand (COD); biological oxygen
demand (BOD); total Kjeldahl nitrogen (TKN), sulfide (SO 3
2À
), sodium (Na
+
), and
phosphate (PO 4
3À ); and the presence of various toxic heavy metals (HMs), viz., iron
(Fe), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), and manganese (Mn), and
nitrogen-containing complex organic pollutants and endocrine-disrupting chemicals
(EDCs) with low pH (Kaushik and Thakur 2013; Chandra and Kumar 2017b). The
origin of dark-brown color in SW is primarily associated with the low and high
molecular weight (mw) melanoidin pigments, a class of compounds known as
Maillard reaction products (MRPs) (Arimi et al. 2014). Currently, in India, there
are 397 distilleries that are producing approximately 3.25 Â 10
10 liters of ethanol and
generating approximately 40.90 Â 10
15 liters of SW per annum (Kumar and Chandra
2018). Due to high pollution nature of SW, the Ministry of Environment, Forest, and
Climate Change, Govt. of India, has listed ethanol industries at the top among the
“Red category” industries (Tewari et al. 2007). Regarding water and soil pollution,
the Bureau of Indian Standard (BIS) provides guidelines to the central and state
government authorities which would help to decide suitable restrictions on effluent
disposal and to the industry for selecting a suitable site and suitable treatment
technology for effluents prior to their disposal into the environment. Consequently,
distillery effluent must be properly treated before it is discharged into the environment (Tewari et al. 2007). In industry, distillery SW treatment is being carried out
commonly by four routes: (i) concentrate the SW followed by incineration, (ii) direct
oxidation of SW by air (oxygen) at a high temperature followed by aerobic treatment, (iii) anaerobic treatment (methanogenesis) of SW with methane (biogas)
496
V. Kumar and R. Chandra