Cleaner Production Techniques: Beverage Industry

Introduction

Cleaner Production Overview

Cleaner Production (CP) is an initiative taken to prevent the environment by reducing the waste and emissions and increasing the production output by changing existing production parameters and technological advancements. It is a continuous application of an integrated environmental strategy to processes, products and services to increase efficiency and reduce risks to humans and the environment. [1] CP is an unavoidable ingredient for sustainable industrial development and deals with many levels of operations of an industrial process at once.

[2]

The implementation of CP helps to [3]:

Reduce the toxic pollutants and waste disposal from industries.

Use and reuse productive resources and improve productivity.

Improve workplace safety.

Improve organization’s image and strengthening of relationship with stakeholders.

Need for Cleaner Production Strategies in Beverage Industry

Different types of beverages are consumed by different age groups across the whole world. The consumption rate of different types of beverages is shown in Figure 1. The beverage industry all over the world is known to be a significant consumer of water, water being the primary component of most beverages.

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Water consumption in a beverage industry is not just limited to beverage production but also for cleaning and sanitizing of the production machines (Webber 2017). Water is the major ingredient (80%) of a carbonated soft drinks industry out of which about one-third of the water is used for cooling, floor scouring and washing [5]. Moreover, waste water produced from a beverage industry is high in organic and acidic waste, which if released into water bodies poses a threat to the surrounding ecosystem.

Besides these, energy consumption is also high in this industry in the production line with highest usage by boilers, compressors and shrink wrappers. Different types of materials are also used for production and packaging and most often any excess material is wasted. Therefore cleaner production is critical for the beverage industry for judicious use of raw materials, to minimize water usage, harmful emissions and waste production, as well as to recycle and reuse by products.

This review will focus on three aspects of cleaner production in the beverage industry, namely reducing water usage, waste water management and recycling and reuse of cans and bottles.

2. Cleaner Production Techniques: Beverage Industry

2.1 Reducing water usage in beverage industry

Estimations suggest that at least 1 in 4 of the world’s population is likely to live in countries that face chronic or recurrent shortages of fresh water. In such cases the high rate of water consumption by beverage manufacturing companies place a huge burden on the ecosystem. Fresh water use is imperative in a beverage industry. Figure 2 is a schematic representation of fresh water use in different steps of beverage production. It is evident from the figure that process of production that use fresh water also generate huge amounts of wastewater. The water used in the final product in a beverage industry is always fixed. Therefore, water used in cleaning and sanitizing of machines, sprays and bottle machines need to be optimized to prevent wastage. [5]

Identifying opportunities to optimize water usage in a beverage industry is the first step towards reducing water usage. Regular surveys of a manufacturing unit can help check for leaks, incorrectly set, poorly maintained or broken equipment, unidentified connections, redundant lines, unknown or unauthorised use or discharge, and clean water discharges to effluent streams. Once identified, these should be rectified quickly. Quantifying water usage and flow with the help of measuring devices and techniques will help quantify the usage of water, which in turn will help identify and implement strategies to reduce the use. Water consumption is maximum in cleaning of machinery in a beverage industry.[5]

2.2 Reducing water use in cleaning

Conventional cleaning methods involve dismantling of all the equipment parts and thoroughly cleaning them, a process known as cleaned-out-of-place (COP). This technique of COP is applied for complex and difficult to clean machinery that cannot be cleaned where they are placed and require disassembling. COP is associated with several disadvantages like high downtime, inability to reuse the cleaning solution, high labour cost for disassembling and reassembling, etc. [10]

A new technique developed for cleaning purposes in the beverage industry is called the Clean-in-place systems (CIP).[5] This technique employs a spray ball or spray to circulate detergent via turbulence which removes bacteria and chemical residues and can be used to clean interior surfaces of tanks and pipelines of beverages. The cleaning solution in a CIP can be reused when appropriate and are available as single-use, multiuse, or reuse systems, depending on how often the solution is utilized for cleaning and disinfecting. CIP equipment are scalable and portable, reducing the downtime for cleaning as well as lower labour costs. It is ideal to optimize CIP techniques when required for optimal water use in cleaning. Automated CIP systems are highly efficient in optimising water use for cleaning of process equipment, tanks and vessels. [10] Besides this, adopting some simple water saving practices as below can ensure judicious use of water in cleaning.[11]

Pressure washers use up to 60% less water than hoses. Automatic container washers can give water savings of up to 95% compared with pressure cleaning containers. Consider using these when appropriate.

Consider using foam and gel cleaners because they require less rinsing.

Use dry clean-up methods to remove waste product from surfaces before a final clean with water.

Arrange production in larger batches to reduce the instances of cleaning durations

Using shorter cleaning cycles for small or easy to clean items can save water while still maintaining hygiene standards.

Fit automatic shut-off controls to hoses.

Consider automatic switch-off mechanisms that cut off the water supply when the cleaning task is finished.

Some of the simple techniques that can be adopted to reduce water use are as follows.[5] [11]

Maintenance and house-keeping techniques.

Immediate repair of leaks and dripping taps

Check for worn or heavily scaled spray nozzles regularly and replace them as necessary

Fit triggers to hose

Process water use

Use tamper-proof valves to prevent tampering

Use recirculating ring main for the distribution of hot or chilled water or lag or trace-heat longs runs of pipework to reduce heat loss/gain.

Fit meters to measure water use for the whole site individual high-consumption process

Improve plant washing procedures

Control flow rates of spray, sealing and cooling water supply

Use high pressure jets and sprays

Steam trapping and condensate recovery

Introduce or make greater use of CIP technology

Replacement of flow-through system with recirculation, recycling and reuse systems

Use dry-handling methods instead of wet where applicable and practical

Train staff

Give responsibility for the water reduction plan to a senior manager

Inform staff regarding water use reports and methods in place for water use reduction

Train staff on strategies and methods for optimal water use

Train staff to report broken or defective equipment

Water Re-use

Re-use cooling water as feed water or make-up water in other equipment.

Treat wastewater to either reduce discharge costs or allow reduce/recycling

Reduce the volume of effluent generation

3. Waste water management in beverage industry

3.1 Characterization of wastewater generated from beverage industry

Wastewater generated from beverage industry is high in organic and inorganic waste, is either acidic or alkaline with a pH ranging between 4 and 11, caustic soda, chemical oxygen demand (COD) between 2242 and 11,717 mg/L and biochemical oxygen demand (BOD) of up to 1150 mg/L (Sheldon_2015). The BOD and COD in wastewater are mainly generated from cleaning activities [7]. The BOD generated is mainly related to the spillage and washing procedures in canning, bottling and blending sequences and waste sugar is considered to be the largest contributor to the BOD discharge [5]. The syrup preparation stage is the most polluting activity as it generates rejections rich in sucrose which are readily biodegradable by micro-organisms and thus develop a relatively high BOD/mass ratio [5]. Typically, 100 gm of fructose will result in 70g of BOD.[8] Approximately 62% of the total organic matter is soluble and therefore cannot be removed by mechanical or physical means [8]. COD has been measured mainly in contaminated process water containing oil and fats generated in cleaning in place (CIP) processes in production plant, particularly during pre-rinsing with hot water [6]. Therefore, biological and chemical oxidation is the solution for waste water treatment[5].

The IFC guidelines specify the requirements for COD and BOD levels of effluents from food and beverage industry as specified in table 1. Treatment of wastewater can be accomplished by several chemical and physical water treatment technologies available today. However, choosing the right technology, at the right time is important to reduce the waste water discharge. It is also important to consider looking at techniques to recover useful by-products and materials from this wastewater that could be reused in other areas of production.

3.2 Wastewater treatment techniques in beverage industry

In beverage production facilities, wastewater treatment usually comprises some sort of physical pre-treatment for removal of suspended matter followed by biological treatment, either aerobic or anaerobic. Before discharge into municipal sewage system, the spent process water from different individual opera¬tions (bottle washing, juice production, cleaning of tanks and pipes, etc.) is mixed and equalized onsite in large tanks. Tests have been conducted and have shown that the product could be recovered from the highly contaminated pre-rinsing water in production plants and water of drinking quality could be produced from the mixed spent process water. The process steps to achieve this, can be simplified as follows: [6]

Product Recovery from highly contaminated spent process water.

The highly contaminated process water is passed through an integrated microfiltration and oil skimming equipment before passing into the mixing and equalising tank. The product concentrate recovered from the oil skimmer can be reused for production of soap. Figure 3 represents the process flow for recovery of product from highly contaminated water.[6]

Reuse of water from mixed spent process water.

The water from the mixing and equalising tank is pre-treated using a membrane bioreactor and UV pre-disinfection to remove suspended solid, dissolved organics and also reject microorganisms. The second stage is a two stage Nano filtration stage to remove residual organic and inorganic impurities. The third stage is a UV disinfection stage which is to meet the drinking water standards. Figure 4 represents the process flow for reuse of water from mixed spent process water.[6]

Fig 4: Process flow of mixed spent water for water reuse.

3.3 Anaerobic processes

Anaerobic processes are very commonly used in the beverage industry for the treatment of wastewaters. These have been in use since 1970s. it is available in different configurations such as anaerobic filter, fixed film reactor, expanded bed anaerobic reactor. The Upflow Anaerobic Sludge Blanket (UASB) and its derivative technologies are the foremost method with roughly 90% of industrial anaerobic treatment systems based on this configuration. The expanded granular sludge bed (EGSB) reactor, which includes an internal recirculation of effluent, typically housed in a reactor body enhances substrate-biomass interaction within the treatment system by expanding the sludge bed and increasing hydraulic mixing, which normally builds up to 16 m. The EGSB reactor can be operated at higher up flow velocities (Vup) of up to 6 m/h with a high recycle ratio. Therefore, the EGSB reactor is capable of treating high strength organic wastewaters up to an OLR of 30 kg COD/m3d.[12][13]

3.4 Other processes

Other techniques are also in use. For treating wastewater from bottle washing process in soft drink industry, processes like reverse osmosis, desalination and ion exchange methods are used. Water treatment techniques involving electrochemical methods are used to treat wastewater from vine-making industry. This involves processes like electro oxidation, electrocoagulation using stainless steel, iron and aluminium electrode sets with simultaneous sonication and recirculation in strong electromagnetic field. Ozonation combined with UV irradiation in the presence of added hydrogen peroxide is used for post-treatment of the effluent. [14]

3.5 Generation of useful by-products from wastewater

Bioethanol production [16]

Soft drink products rejected due to quality policies or the ones that are returned from the market due to a lack of gas or having passed the expiration date have high sugar content. The yeasts ferment the sugar content from these waste and generate bioethanol. Bioethanol can be used as an alternative for transport fuel or energy production.

Hydrogen production [15]

Wastewaters are very useful raw materials for hydrogen production that do not incur production costs. Wastewaters are high in organic waste which makes it a choice for biological production of hydrogen. Wastewater from beverage industry are usually high in carbohydrates, which make them ideal sources for hydrogen production by fermentation. Biological production of hydrogen from wastewaters can be optimized for sustainability by combining fermentation with the production of high value-added products, such as organic acids and biopolymers. Hydrogen produced can be used for generating electric power without pollutants. Studies have demonstrated the feasibility of continuous hydrogen production in upflow anaerobic packed-bed reactors using soft-drink wastewater as the feedstock, yielding 3.5 mol H2 mol-1 substrate.

4. Recycling and reuse of cans and bottles

Recycling and reusing bottles and cans in the beverage industry can reduce costs and minimize wastage. Some of the recycling areas to look at are as below.

4.1 Recycling of aluminium beverage cans

Recycling aluminium can to reuse them uses 95% less energy than producing it from raw materials. The recycling process generates only 5% of the greenhouse gas emissions. For example, Brazil recycles 98.2% of total Aluminium cans whereas Japan recycles 82.5% cans. These two countries are the top 2 with the largest aluminium recycling rates.

4.2 Beverage Carton Recycling

Wood Fibre composition in the carton packing can be used for other paper board products. Aluminium and other polymers can be used as composite material for products such as roof tiles to industrial raw materials or energy recovery. One ton beverage carton recycling prevents 900kg greenhouse gas emissions and 2-3 m^3 of landfill.

Discussion and conclusion

The consumption and demand of water management and effluent treatment are top priorities in most of the beverage industries. Cleaner production implement and sustain policies that aim to ensure that production is carried out in a manner that is both cost-effective and environmentally sound. CP techniques are implemented in these industries to optimize the use of water during the process and reduce or eliminate the toxicity of the waste water generated. Methods like production of bioethanol and hydrogen by-product from waste water is the pre-eminent factor of CP techniques.

The study by various researchers at different beverage industry suggest that the maximum amount of water wastage is in process like cleaning and sanitizing of machines, sprays and bottle machines. The specific water intake (SWI) of beverage industries should be set at 2.3 m3 m-3 of final drink produced[5]. This SWI target can be achieved by using CIP techniques for cleaning which will utilize the water in an optimal manner. Furthermore, proper maintenance, housekeeping and training staff members can result in optimum usage of water. The waste water can also be treated with microfilters, oil skimming equipment, UV filtration, anaerobic process to reduce the toxicity and also for reusing the water. Recycling and useful by-product production from waste is also an exclusive feature of CP technique.