LIFE CYCLE ASSESSMENT OF GHG (GREEN HOUSE GASES) EMMISSION DUE TO DAIRY CATTLE IN INDIA & MITIGATION STRATEGIES FOR REDUCING CARBON FOOTPRINT FOR DAIRY IN INDIA
The demand for sustainable dairy production and processing is increasing day by day. Dairy sector is considered as a hotspot in the environment footprint scenario due to emission of greenhouse gases (GHG), depletion in natural resources etc. Maximization of societal benefits, improvement in peoples’ socio-economic conditions along with decrease in the adverse effects on the environment have, therefore, been emphasized by scholars. The life cycle assessment (LCA) studies of milk production, processing and marketing are analysed to find a way out for reducing the harmful environmental effects, which can be achieved to a great extent if green technologies comprising of sustainable, energy-efficient, environment-friendly technologies are used. Use of solar-powered electricity, non-thermal techniques such as high-pressure processing, pulsed electric field, radio frequency processing, pulsed UV light processing, bactofugation, ultrasound processing, irradiation, cold plasma, ozone treatment, enzymic hydrolysis, membrane processing etc. in the dairy industry has the potential to mitigate environment related issues. However, some of the above stated technologies may release GHG as it consumes electricity during their operation. Better utilization of dairy by-products, such as whey, buttermilk, ghee residue etc., can greatly reduce the environmental load. Treatment of dairy effluents and its reuse would decrease the depletion of natural resources and impact on the environment. The concept of green technology has already been accepted by the Indian dairy industry, but its proper implementation is still in infantile stage and needs up gradation.
Milk and milk products play a crucial role in sustaining life of people. However, production of raw milk, processing of dairy products and their distribution significantly influence the environmental carbon footprint. Several LCA studies have been carried out to assess the impact of dairy sector on environment and to facilitate production of dairy products.
Life Cycle Assessment (LCA) is an acknowledged environmental impact assessment tool to calculate greenhouse gas (GHG) emissions of dairy production. The LCA method systematically analyses production systems to account for all inputs and outputs for a specific product and production system within a specified system boundary. The system boundary is largely dependent on the goal of the study. The reference unit that denotes the useful output is known as the functional unit and has a defined quantity and quality, for example a litre of milk of a defined fat and protein content.
LCAs and carbon footprints
A product carbon footprint is based on LCA methodology. Greenhouse gases are all gaseous substances for which the IPCC has defined a global warming potential coefficient. They are expressed in mass-based CO2 equivalents (CO2e). The main agricultural greenhouse gases are carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4).
An increase in the GHGs emission is noticed each day due to increased population, consumption patterns, production volumes and biggest of all is the ignorance about the detrimental effects of these emitted gas on our life and our future generations. The dairy sector now has a methodology that will allow the calculation of carbon footprint of dairy products. The International Dairy Federation wanted to build a tool to help the dairy sector to identify, quantify and evaluate emissions. The main objective of CF calculation is to build an action plan to reduce GHGs emissions. In order to reduce GHGs emission from dairy sector, it will be crucial to transfer the knowledge to dairy farmers, optimize farming system, reduce the energy consumption and proper management of waste.
The product carbon footprint is the sum of the greenhouse gases emitted throughout the life cycle of a product within a set of system boundaries, in a specific application and in relation to a defined amount of a specified product.
One example of a carbon footprint is obtained by calculating all the GHGs emitted during the production of one litre of semi-skimmed milk, packed in a specific type of paper carton, up to the point when the milk leaves the manufacturing plant gate.
The reference unit that denotes the useful output is known as the functional unit and has a defined quantity and quality, for example a litre of fresh milk of a defined fat and protein content in a defined type of package.
Other environmental impacts are commonly included when doing a full LCA (e.g. water use, land use, toxicity, eutrophication, biodiversity), whereas a carbon footprint only includes the climate impact category. The decision to calculate the carbon footprint of a product is a conscious decision to focus on only one environmental indicator.
The Carbon Footprint (CF) is a measure of the total amount of CO2 emissions that is directly and indirectly caused by an activity or is accumulated over the life stages of a product (Wiedmann and Minx, 2007). Carbon foot print is a footprint of various activities which leads to emission of Green House Gases (GHGs). Thus, it is a measure of the GHGs and is measured in terms of CO2 equivalent. The environmental pollution has adverse effect on the living kingdom whether it be humans, cattle, rodents, aqua life and others. The recently encountered thunder storms of Kedarnath, Tsunamis, earth quakes, flood in Jamu and Kasmir, Hud Hud cyclone, global warming leading to melting of ice glaciers, increase in sea levels etc. are some of the detrimental effects. Many governments and various national and international agencies are working to reduce the effects of carbon emission and to have a green environment. The dairy sector is responsible for 2.7 % of global emission. In dairy sector, the emission starts from cropping the feed for milch animals to the consumption of milk products (Gerber et al., 2010). The various methods for measurement of carbon footprint as well as measures to control the carbon footprint are discussed (Beauchemin et al., 2008).
Concept of Carbon Foot Print
The use of the term “footprint” is to describe the impact of industrial production or consumption activities. It was first developed by planners at the University of British Columbia (Wackernagel and Rees, 1996). The term “carbon footprint” originated from the ecological footprint concept. A carbon footprint focuses on processes and practices related to the emission of CO2 and other greenhouse gases. The term carbon footprint is commonly used to describe the total amount of CO2 and other GHGs emissions through the life cycle of the product (Carbon trust, 2008; Wiedmann and Minx, 2007). A carbon footprint is often expressed as tons of CO2 or tons of carbon emitted, usually on an annual basis (Growcom, 2008). The carbon footprint is broadly classified in two classes as primary and secondary footprint. The primary footprint is a measure of our direct emissions of CO2 from the burning of fossil fuels including domestic energy consumption and transportation. The secondary footprint is a measure of the indirect CO2 emissions from the whole lifecycle of products.
Green House Gases
The chemicals present in the atmosphere, termed as GHGs have certain radiation blocking properties which trap the sun’s energy in the earth’s atmosphere, creating a type of insulation. This leads to higher temperatures on earth than would otherwise occur. These GHGs are H2 O vapor, CO2 , CH4 , O3 , N2 O, Hydrofluorcarbons (HFCs), Perfluorcarbons (PFCs), Sulphur hexafluoride (SF6 ) (Alfons, 2008). The latest report indicates that CO2 level in the environment has reached to 402 ppm (Kiley, 2014). It is reported that if current rates of emission continue, the CO2 concentrations are projected to reach a range of 535 to 983 ppm by the end of the 21st century (Gupta, 2012). The emission of GHGs from various domestic and industrial activities are causing global warming. This has led to variation in season and landscapes, rising sea level, stronger storms, increase in heat related illness and diseases. Reduction of GHGs emissions will aid in protecting ourselves, economy and adverse climatic changes (Roger and Brent, 2007). The records of surface temperature over the last century show that there has been a gradual increase in average temperature around the word.
Effect of Energy Use on Carbon Footprint
Energy used is the main cause of emissions of GHGs at the processing and transportation stages. The reduction of energy consumption by 1 kilowatt hour saves 3 kWh of primary energy, which comes mainly from fossil fuels. Improving energy efficiency, a conversion to renewable energy systems causes a dramatic reduction in GHGs. The world average energy consumption is equivalent to 2.2 tons of coal (Desai et al., 2010). In India coal meet 50% of commercial energy requirement, oil accounts for 36% of energy consumption and natural gas accounts for 8.9% of energy consumption. Green house gases emission from electricity generation using different sources of energy are listed below
Energy source kg CO2 / MWh
Coal or oil 1030
Natural gas 622
Anaerobic digester 46
Solar PV 39
Nuclear 17
Wind 14
Carbon Footprint and Milk Industry
Agriculture today is one of the main reasons why three planetary boundaries (climate change, biodiversity loss and changes in the global nitrogen cycle) have already been transgressed (Rockstromer et al., 2009). It is found that largest share of the GHGs emissions occurs before farm gate (Flysjo, 2012). The most important GHGs generated by dairy industry are methane, nitrous oxide, carbon dioxide and some refrigerants such as HFCs and CFCs (Vora, 2010). The major source of CH4 emission is due to enteric fermentation of animals (Hospido, 2005). Nitrous oxide (N2 O) emission is due to production and use of fertilizer, manure storage. Carbon dioxide (CO2 ) emission occurs due to use of energy at farm level as well as processing level (Thomasen et al., 2008). There are two main sources of GHGs at the manufacturing level which are given below. • Process energy consumption • Fossil fuel consumption for transport Emission of CFCs and HFCs refrigerant gases from the refrigerating system in the factory may occur in case of leakage from the system. The other important sources of emission are the waste management and packaging of dairy products. Indirect emission outside the dairy plant site occurs due to transportation involved in collection of milk and delivery of products (Vora, 2010). Dairy products are associated with GHGs emissions so as the case for almost all the food products. The demand for dairy products is predicted to be double by 2050 which requires higher production of milk and energy for processing and manufacture of different products. Therefore, it is very important to increase the productivity of our milch animals and to process the milk with minimum use of energy. The process re-engineering, use of renewable energy and optimization of various dairy plant operations are key to reduce the carbon foot print. These challenges can be well addressed by involving effective policy making, R&D work and management at national and international level.
Calculation of Carbon Footprint
The importance of calculation of CF is not only for manufacturers but also to the consumer of the products. The importance of calculation of CF reported by are indicated below (ISO, 2006 a, b). • Identification and reduction of GHG • Creating a benchmark to monitor • Identifying cost saving opportunities • To prepare for possible future effects and national or international policy initiatives • Integrating GHG emissions into decision making • Enabling positive marketing and branding • Empowering consumers to select products with lower product carbon footprint • Demonstrating environmental responsibility leadership to both stakeholders and Consumers.
Life Cycle Assessment (LCA) method is used for the calculation of carbon footprint. LCA methods have been developed by International Organisation for Standardization (ISO), and focuses on the quantification of a range of environmental impacts including climate change, across the whole life of a product – from extraction or growing of raw materials, through product manufacture to use and final disposal. LCA is a structured, comprehensive, and internationally standardized method which involves various steps (Aumonier, 2008). • Describe the product used by the customer • Construct the map diagram of all activities • Annotate the diagram with various detail regarding activities • Indentify CO2 equivalent factors • Identify CO2 equivalent emission factors for the combustion of fuels. • Identify non-combustion-related emission factors • Balance the product map drawn up • Multiply CO2 equivalent factors by quantities of inputs and outputs • Documentation • Verifying CF calculations are typically based on annual emissions from the previous 12 months based upon the life cycle of products.
Kyoto Protocol
The Kyoto protocol is a protocol to the United Nation Framework Convention on climate Change (UNFCCC), aimed at fighting global warming. It is for achieving stabilization of GHGs concentration in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. The Protocol was initially adopted on 11, December 1997 in Kyoto, Japan and entered into force on 16 February, 2005. The protocol has been signed by 187 states (Sheth, 2010). Total number of parties under this protocol is 192. In them 40 are under Annex I, 23 are under Annex II and other are non Annex countries. The protocol allows several flexible mechanisms such as emissions trading, the clean development mechanisms and joint implementation. India signed and ratified the protocol in 26 August, 2002. India is coming under non annex countries.
Reduction of Carbon Footprint in Dairy Sector
The variation in GHGs emissions among dairy farms indicates that there is a potential to reduce the CF (Cederberg et al., 2004). CH4 from enteric fermentation is by far the largest single contributor to the CF of milk at farm level (Beauchemin et al., 2008). Increasing the quality of feed, especially roughage, can reduce enteric CH4 production (Danielsson, 2009). Less use of fertilizer and use of manure for biogas production can also reduce carbon footprint (Holm-Nielsen et al., 2009; Agus, 2011). Synthetic fertiliser (ammonium nitrate) produced with BAT has about half the CF compared to a traditionally produced (Jenssen and Kongshaug, 2003). Optimizing protein feeding can reduce nitrogen emission (Greppa, 2008). Use of alternative energy sources like solar energy, biogas from effluent treatment plant, biomass energy, biomass gassifier (Rathore, 2010) can reduce CF. Reduction in transportation energy, optimum use of packaging material and selection of fuel have great potential to reduce the CF (Berlin and Sonesson, 2008).
Energy Conservation in Dairy Plants
Refrigeration is a major energy consuming utility in dairy plants. It is estimated that electricity consumption of refrigeration plant is about 50-60% of total electrical consumption. The important factors that affect the performance of vapor compression refrigeration system, include evaporating temperature, condensing temperature, sub-cooling of liquid refrigeration system, super heating of suction gas, presence of non condensable gases, volumetric efficiency of compressor etc. Operation of electrical motors at optimum load is very important to get higher efficiency of motor. It is also recommended to avoid repeated rewinding of motors because rewinding leads to 5% efficiency loss. Generation of steam in boilers under optimized conditions, selection of fuel, efficient use of steam produced and recovery of condensate are key factors for the conservation of thermal energy. Water is essential service in dairy plant for many activities. It is necessary to reduce water consumption not only to reduce the pumping cost but also to reduce load on effluent treatment plant. Dairy industry is facing challenge of cost competitiveness, energy conservation and technology up gradation. The following technology up gradation can contribute to reduction of energy consumption. It is reported that total waste of milk and dairy products at consumer level corresponds to approximately 63 Mt CO2 e globally (Gustavsson et al., 2011). Extension of shelf-life of products and avoiding food waste helps in reducing GHGs in post dairy chain (Wrap, 2009).
Standards for Product Carbon Footprint
There are various standards for carbon footprint and there are labels of different standards which are given on the product pack (ITC, 2012). The International Dairy Federation (IDF) has developed a common carbon foot printing approach for the dairy sector including milk production and processing. The guide aims to provide a harmonized approach to calculate the product carbon footprint (PCF) of milk and milk products.
Carbon Zero Programme
The Carbon Zero Programme was developed by Landcare Research to measure, manage and mitigate GHGs and direct energy use for businesses, households and individuals (Carbon Zero, 2007; Smith et al., 2006). Carbon neutral refers to achieving net zero carbon emission by balancing a measured amount of carbon released with an equivalent amount offset, or buying enough carbon credits to make up the difference. The programme has led to many carbon-neutral dairy and food products.
A Common Carbon Footprint Approach for Dairy
Life cycle assessment of dairy operations
Life cycle assessment (LCA) is a tool that systematically analyses the greenhouse gas emission and the other potential environmental impacts of a product during its entire life cycle. Carbon footprint is a measure of the quantity of greenhouse gases, especially carbon dioxide which are released into the environment due to human activities. The adverse impact of each stage in the dairy sector beginning with raw milk production to processing, packaging, transportation and marketing of dairy products, on the global environment has been explored. Production of raw milk and associated agricultural practices showed a significant impact on environment by diminishing the natural resources, loss in soil fertility and biodiversity, causing acidification, eutrophication, water pollution and GHG (majorly methane) emission (Fig. 1) (McMichael et al., 2007; Fantin et al., 2012). Utilization of energy during production, processing and distribution of milk and its products is another cause of environmental footprint. Carrying out LCA for each stage during the production of dairy products as well as their transportation is of paramount importance to lower the environmental footprint to an acceptable level. Waterway transportation produces the least amount of GHG, followed by railways and roadways. Air mode of transportation emits 40 times more GHG than waterways (Boye and Arcand, 2012). Roadway transportation, used mostly by the dairy sector, accounts for 73% of total GHG emissions (Gupta and Singh, 2016). The LCA methods as per ISO:14040 (2006) and ISO:14044 (2006) standards involve quantification of impacts of inputs and outputs at each stage to enable strategy formulation to build up sustainable and resourceful environment. Several models for LCA studies have been developed based on the system boundaries, impact categories and consequences (Baldini et al., 2016; Pernollet et al., 2016). The LCA processes, depending on boundary of analysis in dairy sector, are of three types such as cradle to gate, cradle to grave, gate to grave (Fig. 2). In ‘cradle to gate’ system, the analysis of environmental impact of any product starts from the moment of extraction of raw materials and continues till its entry at the stores. The ‘cradle to grave’ system involves the total analysis of environmental impact starting from raw materials extraction to the disposal phase of the products, while the ‘gate to grave’ system analyses the environmental footprints during the period from transportation of products to the consumer and to the disposal phase of the products.
Novel green technologies
Green technologies could be defined as a set of technologies which help mankind to minimize impacts of horizontally expanding settlements over ecosystems, extract food, feed, fiber, fuel and fertilizer using renewable and non-renewable energies from the environment, facilitate climate regulation, waste decomposition and detoxification, purification of water and air, and improve livelihoods with vertically expanding habitats and to live happily with the cultural and ethnical diversity, while maintaining the ecosystem services and improving resilience (Gunasena, 2019). Green Technology uses science and technology to decrease the harmful effects of human activity on nature. Use of solar-powered heating, cooling, drying, refrigeration, air conditioning and other operations in dairy industry can reduce environmental pollution. Dairy farmers can chill bulk milk using a renewable energy device called biogas milk chiller in which biogas, derived from cow manure, powers the refrigeration unit (Edwin and Sekhar, 2018). Pasteurization and sterilization are the dominant methods in the dairy industry to destroy harmful microorganisms or diminish their deleterious effects on milk and milk products. High processing temperatures to inactivate microorganisms lower the nutritive value of dairy products and adversely influence their organoleptic quality (Wang et al., 2016). Different units in a dairy plant such as boiler, refrigeration unit, water treatment plant, electricity generating sets, pumps etc., consume a lot of energy and emit GHG into the environment (Mekhilef et al., 2011). Use of eco-friendly non-thermal green processes can greatly improve the situation. Condensed milk, skim milk powder, whole milk powder, whey powder, lactose, etc., require high energy during concentration and drying. Energy consumption can be minimized by utilizing membrane filtration technology (Kumar et al., 2013). Microfiltration is used mainly to reduce bacterial load in milk and whey and can, therefore, be an alternative to clarification or bactofugation unit (GésanGuiziou, 2010). Ultrafiltration is utilized to separate proteins from milk or whey and can be used to manufacture whey protein concentrate (Hobman, 1992). Nanofiltration technology is mainly used to demineralize whey or lactose while reverse osmosis (can operate at ambient temperature) is employed to concentrate milk by removing water (Deshwal et al., 2021; Yadav et al., 2022). Use of multiple effect evaporator along with thermo-compressor or mechanical vapour recompression (MVR) unit to concentrate milk requires much less energy as compared to concentration by single effect evaporator (Early, 1998). Energy requirement to evaporate 1000 kg of water from milk using a vacuum pan is 626 kWh while that in 5 or 7 effects evaporator is 126 to 180 kWh, and in 5 or 7 effects MVR is 37 to 52 kWh (Marshall, 1985). In the RO desalination and milk concentration, 4 kWh and 9-19 kWh of energy are required, respectively, for every 1000 kg of water removed (Marshall, 1985). For better heat or energy recovery in the dryer section, a three-stage dryer (a spray dryer integrated with a fluidized bed dryer) can be used instead of a single-stage dryer. Exhaust gases containing sufficient heat can be recirculated in the dryer (Yazdanpanah and Langrish, 2011). A great environmental hazard can happen if milk solids of less than 50 micron size tend to get mixed with exhaust gases escaping the dryer (Singh, 2014). By utilizing cyclone separators or bag filters, fine milk solids can be recovered and product wastage can be minimized (Moejes and Van Boxtel, 2017).
Use of enzymes
Specific and non-toxic enzymes play a crucial role in lowering the carbon footprint in the dairy industry as they accelerate the reaction rate by lowering the requirement of activation energy (Kumar et al., 2020). Enzymes like lipase, protease, esterase, lactase, transglutaminase, amylase etc., are mostly used in the dairy industry to achieve various goals such as flavor enhancement (cheese and ghee), accelerated ripening (cheese), protein crosslinking to provide better body and texture (yoghurt), prevention of lactose intolerance (lactose hydrolysed dairy products) etc. (Abada, 2019). However, the primary usage of enzymes in the dairy industry is for manufacturing cheese. Flavour development in cheese mainly occurs during ripening by proteolysis, lipolysis and glycolysis. The ripening process is energyintensive as cheese is kept at a low temperature for an extended period (6-9 months) for optimum flavor development. Lipase, esterase and protease enzyme have been used to accelerate the ripening process and enhance flavor development by lipolytic or proteolytic pathway (Law, 2001).
Use of preservatives
Indiscriminate disposal of dairy effluents containing perishable milk solids into the environment poses a threat as these generate methane gas on decomposition. Spoilage of the food product not only creates a burden in waste management but also possesses a challenge in feeding the starving population. About 828 million people are starving globally (WFP, 2022) while annual food spoilage in the world was estimated to be 1.3 billion tonnes (FAO, 2011). According to Gustafsson et al. (2013), wastage of dairy products was highest in SubSaharan Africa and lowest in industrialized Asia (Fig. 3). Enhancement of shelf life of food products using approved preservatives can provide partial solution to tackle the food scarcity problem. Chemical preservatives such as sulphites can cause headache, allergies and many other symptoms. Similarly, sorbates and sorbic acid, the common mold inhibitors used in foods, cause urticaria and dermatitis (Sharma, 2015). To prevent detrimental health effects, utilization of bio-preservatives such as nisin, pediocin, lacticin, essential oils etc. instead of chemical preservatives in food products is gaining popularity (Table 1). Bio-preservatives can act as bacteriostatic or bactericidal agents and at the same time can exert influence to maintain the organoleptic and physico-chemical quality of milk and milk products without any adverse health or environmental impact. In nutshell, usage of bio-preservatives can be a suitable approach to achieve the sustainable development goal.
Utilization of dairy by-products
To reduce wastage of milk solids, it is necessary to utilize the dairy by-products for preparing value-added products. Incorporation of casein, caseinate and co-precipitates derived from skim milk (the major by-product of the dairy industry) into food products increases their protein contents. Industrial casein can be used to manufacture a number of products such as adhesives, paints, vulcanized rubber etc. (Badem and Uçar, 2017). Whey obtained during the preparation of chhana, paneer, casein, shrikhand and cheese is the second largest dairy by-product which can be used to prepare whey beverages, whey powder, whey protein concentrate (WPC), whey protein isolate (WPI), ethanol, bio-gas, lactose powder, single cell protein, baker’s yeast etc. (Božanic’ et al., 2014). Whey beverage being rich in electrolytes, serves the dual purpose of thirstquenching and rehydration solution. Whey powder is used to make up the requirement of solids-not-fat (SNF)/ protein content in various food products. Athletes and bodybuilders widely consume food items rich in WPC. Glycomacropeptide isolated from sweet cheese whey can be used for phenylketonuria patients (Sharma et al., 2013). Lactose is commercially used as a filler and bulking agent in pharmaceutical applications (Hebbink and Dickhoff, 2019). It is also used in bakery products to impart flavour and colour, and in confectionary products to improve their body and texture (Chandan and Kilara, 2011). Buttermilk added with salt or spice is normally consumed fresh as a thirst-quenching beverage. Buttermilk powder can be used to make up the total solid (TS) content in certain dairy products. Owing to high phospholipids content and greater water-binding ability, addition of buttermilk powder to yoghurt prevents syneresis (Garczewska-Murzyn et al., 2022). Ghee residue, which is normally thrown away, can be utilized as animal feed and to manufacture various confectionery and bakery products (Roy et al., 2018).
Water utilization and wastewater management
Yield of wastewater in dairy industry is very high as it requires huge quantity of water in every stage from raw milk production to the manufacture of dairy products. Treatment of wastewater, therefore, assumes importance to address environment related issues. For each litre of milk heat treated and chilled, almost twice and thrice the amount of water gets utilized, respectively. Almost 2.4 and 3.6 lakh litre of water is used daily for thermal processing and chilling of milk, respectively in a typical dairy plant (Singh and Kumar, 2009; Irfan and Mondal, 2016). Processing of one kg of yoghurt, cheese, ice-cream and milk powder requires about 0.48-4.0, 0.48-3.9, 0.87-6.5 and 0.07-2.6 litre of water, respectively (Rad and Lewis, 2014), while Klemes et al. (2008) reported that almost 1.8 litre of water, on an average, is utilized per kg of milk product manufactured. About 28, 25, 16, 12, 6 and 6% of total water utilized in a typical fluid milk processing plant are required for CIP (Cleanin-Place), pasteurization, crate washing, operational processes, manual washing and cooling tower, respectively (Rad and Lewis, 2014). Reuse of water in a dairy plant not only saves water but also decreases pollution and damaging impact on environment. In AMUL dairy, effluents discharged from the different sections are first checked for degree of pollution, and if the pollution level is low, the same is treated by membrane filtration technologies for reuse (Tiwari and Srinivasan, 2017). Otherwise, the effluent is discharged after passage through effluent treatment plant. About 47% of water from cheese whey can be recovered by utilising ultra-filtration in combination with reverse osmosis (Meneses and Flores, 2016). About 95% of water was recovered when wastewater collected from flushing and first rinse was subjected to reverse osmosis (Vourch et al., 2008). The treated water was successfully used in boiler, chiller and for external washing of equipment. In addition, rainwater, after proper treatment, can also serve as an economical and additional source of water in dairy plants (Muhirirwe et al., 2022). Appropriate sequence management can also reduce the number of CIP cycles in a plant. If only one packaging machine is available in a dairy plant, milk should be packed before packaging of another product, say dahi. If the opposite is done, milk packaging cannot be started without carrying out CIP, as traces of dahi particles (if present) can curdle the milk. Excessive water should not be utilised during the equipment’s start-up and shutdown. Automated CIP systems and closed cooling systems can further reduce water wastage (Rad and Lewis, 2014). Globally, 4 to11 million tonnes of dairy waste is discharged into the ecosystem (Ahmad et al., 2019). These effluents contain lactose, fat, chlorides, sulphates and many other organic components, which increase their biological oxygen demand (BOD) and chemical oxygen demand (COD) values. Dairy wastewater has a BOD and pH value of 530 mg/L and 6.5, respectively, whereas the values for COD, total solids, dissolved solids, suspended solids, volatile solids and dissolved fixed solids are 790, 2532, 1803, 729, 1702 and 1562 mg/L, respectively (Patil et al., 2014). The wastewater not only increases the sewage system’s organic load but also reduces the dissolved oxygen content in the water reservoirs, thereby severely impacting aquatic life. In addition, these water reservoirs serve as breeding sites for mosquitoes, insects and flies, resulting in increased incidences of malaria and dengue (Alwasify et al., 2018). Traditional methods (coagulation, precipitation, biodegradation, sand filtration and activated charcoal adsorption), established methods (solvent extraction, evaporation, oxidation, electrochemical treatment, membrane separation, membrane bioreactors, ion exchange and incineration) and emerging methods (advanced oxidation, bio-sorption, biomass and nanofiltration) can be used to remove contaminants from wastewater. Wastewater in a dairy plant is generally treated using aerobic or anaerobic biological method. The methodology for treating wastewater should be judiciously chosen as it can contribute to the emission of GHG like carbon dioxide and methane (Keller and Hartley, 2003). Aerobic treatment for decreasing COD emits almost twice the amount of carbon dioxide gas, in contrast to an anaerobic treatment which is more economical and environment friendly. Measures should, therefore, be followed to trap carbon dioxide and methane gas to safeguard the environment and produce green energy like bio-gas (Keller and Hartley, 2003). Various green or eco-friendly techniques such as membrane biological reactor, electrocoagulation, advanced oxidation processes, activated carbon adsorption processes etc., can also be used to treat wastewater (Yadav et al., 2019).
Packaging
About 69% of the packaging materials is used for packaging of food and beverages, followed by 14% for clothing, 9% for educational and recreational purposes and the rest 8% for home and interior purposes (Pongrácz, 2007). Plastics derived from synthetic polymers take a long time (may be more than 500 years) to degrade, which led to development of biopolymers derived from renewable resources like mango peel, pumpkin residue, blueberry waste, whey protein, wheat straw fibres etc. (Thulasisingh et al., 2021). Biodegradable plastics are degraded within a short time in the environment. However, their rigidity, flexibility, and barrier properties are considerably less as compared to synthetic plastics. Used packaging materials usually are dumped into the landfills of municipality, which leads to extensive production of GHG. Paper constituted 5.8% of the municipal solid wastage (MSW), followed by plastics, metals and glass accounting for 3.9, 1.9 and 2.1% of the MSW, respectively (Gupta et al., 1998). Average composition of municipal solid waste in Kolkata, India, during 2010 has been depicted in Fig. 4 (Das and Bhattacharyya, 2013). As of 2018, almost 4.3 million tonnes of plastic MSW were generated on yearly basis in India (Ryberg et al., 2018). Plastics, being derived from synthetic polymers, may get anaerobically decomposed in landfills, resulting in methane emissions. Source reduction is one of the best alternatives for reducing the quantity of waste generated, which can be achieved by reducing or light weighting, reusing and recycling. Waste generation can be decreased by employing bulk delivery system or lowering the gauges of packaging materials. Marsh and Bugusu (2007) opined that by reducing the thickness of aluminium cans and paper board, almost 5.1 and 7.5 million pounds of aluminium and paper, respectively could be saved annually. Reusing of glass and cans, after proper washing with suitable detergents, also helps in reducing the wastage. The thermoplastic wastes can be reutilized by crushing and hot extruding it along with adhesives to manufacture plastic bottles (Briassoulis et al., 2013). Multi-layered plastics, which are difficult and uneconomical to recycle, can be used in the energy and chemical industry, construction material and textile industry and for manufacture of carbon nano-materials (Pan et al., 2020). India has already used plastic waste in development of more than 1 lakh kilometre of road, which not only possess superior strength, heat resistance and durability but also require less maintenance compared to ordinary bitumen roads (Trimbakwala, 2017; Pan et al., 2020). Apart from chemical and mechanical recycling, biological recycling is also gaining a lot of attention. Complete biodegradation of polystyrene by using mealworm larvae has been made possible in China (Yang et al., 2015). Recycling of paper and paperboard not only reduces the carbon footprint considerably but also saves cutting of trees. To get the desirable strength, recycled paper should be blended with virgin paper at an appropriate ratio (Deshwal et al., 2019). However, such paper should not be put in direct contact with food to prevent migration of ink (if any) into the food. Paper and paperboard can also be converted into bioethanol, which is more cost-effective as compared to petrol (Wang et al., 2013). Incineration of plastic wastes (though not much eco-friendly) facilitates rapid waste disposal, emptying of landfills and can also be used to generate electricity (Idumah and Nwuzor, 2019). Online shopping produces almost 4.8 times higher packaging waste in comparison to offline packaging (Kim et al., 2022). The government and its regulatory agencies play a vital role in reducing packaging waste. According to plastic waste management rules (EPR-PWM, 2020), Government of India (GoI), it is the duty of the producer to collect and recycle the product under extended producers’ responsibility clause (Pani and Pathak, 2021). Use and sale of non-recyclable multi-layered plastic has been banned under EPR-PWM (2020). Initiatives have also been taken by the GoI to phase out usage of single use plastics by 2022 (Pani and Pathak, 2021). Already, plastic carry bags having thickness below 50 micrometres has been banned. Nevertheless, proper implementation of these rules and regular inspection is a necessity for success of these efforts.
Green technologies in transportation of dairy products
Burning of fossil fuel during transportation of raw materials, feed, fodder, dairy products etc., emits GHG. Transportation accounts for about 24% of total carbon dioxide emissions world-wide due to fossil fuel combustion (Singh et al., 2019). It is the major GHG (96%) produced during transportation, followed by methane (3%) and nitrous oxide (1%) (Eide, 2002). Insulated trucks are preferred for milk and milk products, but transportation of frozen dairy products requires refrigeration, which again increases the carbon footprint. In food sector, transportation alone accounts for 5-50% of GHG production depending upon the products and processing system (Boye and Arcand, 2012). Improvement in vehicle’s efficiency, utilization of low-carbon fuels and proper logistic management are some of the ways to diminish GHG emissions from transport sector. A 10% reduction each in weight of the vehicle and aerodynamic drag can significantly enhance the fuel economy by 7 and 2%, respectively (Greene et al., 2010). Improvement in transport logistics, avoiding high-traffic roads, loading of vehicles up to its maximum capacity and reducing empty return trips etc. can significantly decrease GHG emissions. Driving the vehicle at prescribed speed, better shifting of gears and reduction in the number of startstop of the vehicle can decrease fuel consumption by 7% (Mckinnon and Piecyk, 2009). Use of secondary, tertiary and quaternary packaging materials can help in transportation of more food products at a time. Pirog et al. (2001) noticed that local procurement of raw materials reduces GHG emissions. Use of bioCNG, bio-diesel and hydrogen, instead of petrol and diesel, can again help in protecting the ecosystem through reduction in GHG emission (Negi and Mathew, 2018).
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
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Reference-On Request.
