Waste Quantification and Cleaner Production (CP) Potential in Industry

National Cleaner Production CentreSri Lanka

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Waste Quantification and Cleaner Production (CP) Potential in Industry

1.0 IntroductionCommitting to environmentally friendly business practices is commendable and potentially profitable. But unless it gets a sense of the waste inventory that the business creates, all efforts may fail. In the case of going ‘green’ and reducing company’s waste, it must not only identify what kind of waste that want to reduce, but how much wastes are producing. By quantifying the amount of materials, paper, energy and other resources that the business uses inefficiently, it will be better positioned to eliminate it. And doing so isn’t just serving a ‘noble’ purpose to the community and the planet; it will provide repeat bottom-line benefits for the business.

1.1 Quantifying the wasteQuantifying the waste does three things. First, it helps to distinguish between the big hitter and the nice to‐ ‐ ‐have improvements so you focus on the most important opportunities first. Second, it makes the organization aware of the cost of a delay in tackling a ‘big hitter’. And third, quantifying the waste enables to‐ have more meaningful discussions with other parts of the organization whose support need to change the processes that cause the waste. The gravity of the waste stream and potential benefits in overcoming this waste can be better understood by quantifying the waste.

Step 01: Preparation of Process Flow DiagramA process flow diagram (PFD) is a diagram commonly used in engineering to indicate the general flow of plant processes and equipment. This illustrates the material and energy flows and clearly shows what wastes are generated and where these wastes are generated.

Step 02: Material and Energy BalanceMaterial Balance: Material quantities, as they pass through processing operations, can be described by material balances. Such balances are statements on the conservation of mass. Material balances are fundamental to the control of processing, particularly in the control of yields of the products.

Energy Balance: Similarly, energy quantities can be described by energy balances, which are statements on the conservation of energy. The increasing cost of energy has caused the industries to examine means of reducing energy consumption in processing.

If there is no accumulation, in both material and energy balances, what goes into a process must come out. This is true for batch operation. It is equally true for continuous operation over any chosen time interval.

2.0 Data collection and Measurements for Material and Energy BalanceBased on the flow diagram and through site-inspection the team should identify wasteful unit operations. Along with existing data on consumption of resources and materials, this work is the base for deciding the focus of the Waste assessment. The focus area should be selected so it is likely that economical attractive waste quantification and reduction options can be identified. Unit operations that result in high losses of materials or products; or where there is a high reprocessing rate should be included in the focus area.

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Figure 01 : Process flow diagram for DC manufacturing Industry

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Next, the data for making material and energy balances should be collected. This will require a lot of work and measurements. It can be necessary to install meters to measure the consumption of water and electricity. Quantifying the inputs and outputs is the only way to identify losses that normally go by unnoticed.

Following steps would be ideal to derive the figures for material and energy balance. Thus far, it should learn about the process variables that it needs to describe the materials/energy entering a process stream. It should learn how to a) Specify a process streamb) Specify a process unitc) Do a material/energy balance on a process unitd) Do a material/energy balance on a sequence of process units.

Classification of Processes should be done based on how the process varies with time (whether it is a steady state process or unsteady state process) and how the process was built to operate (Whether it is a continuous process, batch process or semi batch process).

Type of material/energy balance should be decided upon the classification of processes and types of balances as follows;

Differential Balance is a balance taken at a specific instant in time. It is generally applied to a continuous process. If the process is at steady state, a differential balance applied at any time gives the same result.

Integral balance is a balance taken at two specific instants in time. It describes what has happened over the time period between the two points. An integral balance is generally applied to the beginning and the end of a batch process. It accounts for what happens to the batch of materials.

2.1 Type of Data and method of collection2.1.1 Data on the input of raw and processed materials are available from the accounts department or the

logistics department;o Procurement records : Referring these records, material input can be quantified in different

terms such as raw material, furnace oil, fire wood, etco Utility bills: Utility bills such as electricity bills and water bills give the quantities of amount of

usage in terms of kWhr of electricity and m3 of water etc.2.1.2 Data concerning output flows are available from the production planning and control departments,

from the foremen or workshop masters themselves, from job planning or production records;o Control sheets.o Sales records: Number of items produced gives the material out from the whole production

process2.1.3 Waste (Non product outputs)

o Garbage records: Records of waste left for disposal recycling or treatment.o Sales Records: Get sales rejects from sales records

2.1.4 Measured dataThe data required for a material flow analysis can be obtained from different sources such as production data acquisition system, log books, routine measurements, individual measurements, information from the production department and documentation of equipment, but also by calculating or estimating. If all these sources do not permit the collection of the necessary data on quantities and values you will have to carry out your own measurements or else rely on estimates.

2.1.4.1 Quantity of Material The first step is to look at the three basic categories: materials in, materials out and materials stored or wasted. Having decided which material need consideration, the basis for the calculations has to be decided.

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Mass of raw material entering the process in a batch system, Mass per hour in a continuous process.

Sometimes it is unimportant what basis is chosen and in such cases a convenient quantity such as the total raw materials into one batch or passed in per hour to a continuous process is often selected. Having selected the basis, then the units may be chosen such as mass, or concentrations which can be by weight or can be molar if reactions are important.

2.1.4.2 Quantity of EnergyAnalysis of energy use can be done by installing sub-meters in different plant locations to pinpoint actual energy usage per area. This is a good source data for allocating energy use. The plant manager can also list all equipment used and the corresponding operating hours. With this information, he can create spreadsheet information and generate charts useful for analysis.

Important points to consider when collecting site load dataa. Operating hours - This can be gathered from plant personnel. It is important to ensure the accuracy

of this data because much of the potential for energy savings lies on correct estimation of the equipment’s operating hours.

b. Duty cycle - Machines such as large electric motors have varying loads and hence, different power requirements.

c. Actual power consumed - For electric power users, this is based on either 3-phase current/voltage readings or power analyzer measurements (e.g., direct kW which incorporates power factor). For fuel users, tank readings of monthly consumption estimates and flow meters with total can be sources of measurement.

Energy balances can be calculated on the basis of external energy used per kilogram of product, or raw material processed, or on dry solids or some key component.

Calculating Electrical Energy: The amount of electrical energy used by an appliance (motor, heater, air conditioner, lights etc) is found by multiplying its consumed power by the length of time of operation. The units of electrical energy are usually watt-seconds (joules), watt-hours, or kilowatt-hours. For commercial purposes the kilowatt-hour is the unit of choice.

Calculating Thermal Energy:Measurements are needed to determine efficiencies of generation, distribution & Utilization of thermal energies. Boiler efficiency tests are carried out to determine steam generation to fuel ratio. Condensates coming from coil, jackets, and evaporators are collected to arrive at norms for each operation. Exhausts of furnaces, boilers are quantified by analyzing them with our set of equipments. Fixed heating load, start up load & insulation losses are determines. Based on the above results thermal energy balance is done for reference period of any time frame.

2.2 Recording of DataDifferent types of work sheets are used to record measured data of material and energy usage of the daily production process. Maintaining work sheets are simple to follow and easy to fill and continue for longer period. Also it is possible to add any instructions and comments where ever possible. Generally, in work sheets sensitive data are not included. Following are some work sheets commonly used in industry;

WS 1 : General data (date, total production, working hours, no of workers etc) WS 2 : Procurement Data on Inputs (Month, quantity purchased and used, balance stock etc) WS 3 : Water Usage (Date, Process, quantity of usage, temperature etc) WS 4 : Steam Usage (Date, Process, quantity of usage, temperature etc) WS 5 : Electrical Consumption (Date, Process, quantity of usage, temperature etc)

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Process step 01

Process step 01

Process Unit

Raw materials

Catalysts

Water/air

Energy

Recycling

Gaseous emissions

Intermediate products

By-products

Wastewater

Solid waste

Energy waste

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WS 6 : Layout Plan (Layout diagram indicating all operations) WS 7 : Production Data (Date, Total production, by products etc) WS 8 : Maintenance Records/Downtime (Date, Type of Maintenance/machine, down time etc) WS 9 : Solid Waste Records (Date, type of waste, quantity) WS10 : Boiler Performance ( Fuel consumption, Stack temperature, operating pressure etc) WS11 : Material Flow Sheet (Date, Type of raw material, Input etc) WS12 : Packaging Material Data (Date, Type of packaging, used quantity) WS13 : Sales Data (Date, Production dispatched, sales returned etc) WS14 : Waste Water Analysis (Date, Demand, pH, Quantities of chemicals used etc)

2.3 Shortcomings / difficulties in data collection and how to avoid themShortcomings/difficulties

Lack of data on utility consumption/material input etc to see trends into the future Taking measurements based on numerous assumptions &/or lacks scientific foundation Insufficient, inaccurate, un-calibrated, or poorly placed measuring devices Undetected mistakes are made in the data collection or analysis Unsteady processes made unreliable data

How to overcome To overcome shortcomings and difficulties, it is required to occupy knowledgeable team to collect

data by reviewing primary data and tabulating. Measurements have to be repeated after analyzing the process very carefully to avoid any mistakes

due to the unsteady status of the processes lines. All equipments and meters used to get measurements have to be calibrated before using for

measurements. Personal who involved in the measurements has to be trained to minimize human errors.

3.0 Developing the material balanceDetails on material and energy consumption for the production process is tabulated on work sheets have to be utilize to develop material and energy balance, using balance principal based on law of conservation of mass and energy.

A material/energy balance can be written using the total mass/energy in each process stream. This is called a total balance. A separate mass/energy balance can be written for each component involved like water, raw material 1, raw material 2, electrical energy, heat etc. These are called component balances.

Figure 02 : Material and energy balance for a unit process Figure 03 : Total material & energy balanceThe total of what goes into a process must equal the total of what comes out. Preparing a material balance is designed to gain a better understanding of the inputs and outputs, especially waste, of a unit operation so that areas where information is inaccurate or lacking can be identified. The flow of a certain material can be retraced from the point of entry into the company following its way through diverse processes to the point

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Input Output

MaterialRaw material, Water, other material

Energy carriersFuel, gas

EnergyElectricity, Heat

Products

Material WasteSolid waste, gases, wastewater

Energy emissionsWaste heat

Industry

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of output. Ideally you will be able to draw up a coherent material balance: input has to be equivalent to output. The same applies to detailed balances and individual process steps. A good estimate is always preferable to having no balance at all. An estimate with an accuracy of 80 to 90% is usually sufficient.

If the unit operation, whatever its nature is seen as a whole it may be represented diagrammatically as a box, as shown in Figure 01. Ideal situation of a material and energy balance would be the mass and energy going into the box must balance with the mass and energy coming out. But practically it does not happen and actual situation.

Figure 04 : Mass and Energy Balance for a Industry

The law of conservation of mass leads to what is called a mass or a material balance. Mass In = Mass Out + Mass wasted

Material in = Products + Wastes (non product outputs)

The energy coming into a unit operation can be balanced with the energy coming out and the energy stored. Energy In = Energy used + Energy wasted (losses)

It is required to do a mass/energy balance on a process unit and continue it on a sequence of process units.

4.0 Waste stream quantificationWaste is defined as a non-product output with a negative or zero market value. Waste can be solid, liquid or have a paste-like consistency. Water and air-polluting emissions – although they are non-product output – are not regarded as waste. If the value of the waste fluctuates according to market conditions, accumulated net costs/revenues during the reporting period are used to determine the market value.

By looking at the material balance of each unit processes, it can be identified that what waste is generated at which process step and why. The individual and sum totals making up the material balance should be reviewed to determine information gaps and inaccuracies. If outputs are less than inputs look for potential losses or waste discharges. Outputs may appear to be greater than inputs if large measurement or estimating errors are made or some inputs have been overlooked.

When calculating up a balance, remember the principle of conservation of masses. This applies to the entire company as well as to the system elements defined as ‘production steps’. In a stable system the mass input into an element has to be equivalent to the output. All raw and processed materials entering a certain system have to leave it as a product, waste or emissions. For this reason we have to calculate in mass units [kg].

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4.1 Presenting of Material/Energy dataPictorial interpretation of the materials/energy flows. It shows volumes, proportions, ecological relevance among other characteristics. There are four major types of pictorial interpretation types are presented below;

4.1.1 TablesA table is a means of arranging data in rows and columns. The use of tables is pervasive throughout all communication, research and data analysis.

Input Output DeficitWaste paper 10 ton/dayFibres 8,500 kg/dayFillers 900 kg/dayWater 600 kg/dayBack waterWater 400 ton/day

Decker filtrateFibre 350 kg/dayFillers 450 kg/dayWater 200 ton/dayPulpFibre 8,075 kg/dayFillers 400 kg/dayWater 190 ton/day

Total inputFibres 8,500 kg/dayFillers 900 kg/dayWater 400.6 ton/day

Total outputFibres 8,425 kg/dayFillers 850 kg/dayWater 390 ton/day

Not accounted75 kg/day (1%)50 kg/day (6%)10.6 ton/day (3%)

Table 01: Sample Material Balance for a Hydropulper

4.1.2 Pie ChartsA pie chart (or a circle graph) is a circular chart divided into sectors, illustrating proportion. In a pie chart, the arc length of each sector (and consequently its central angle and area), is proportional to the quantity it represents. When angles are measured with 1 turn as unit then a number of percent is identified with the same number of centiturns. Together, the sectors create a full disk. It is named for its resemblance to a pie which has been sliced.

4.1.3 Data Flow DiagramsA data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system. A DFD provides no information about the timing of processes, or about whether processes will operate in sequence or in parallel. It is therefore quite different from a flowchart, which shows the flow of control through an algorithm, allowing a reader to determine what operations will be performed, in what order, and under what circumstances, but not what kinds of data will be input to and output from the system, nor where the data will come from and go to, nor where the data will be stored.

4.1.4 Sankey DiagramsA Sankey diagram is a graphic illustration of flows, like energy, material or money flows. Usually the flows are illustrated as arrows.

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17264.6

76.44

3233297.5914.43

375sorting

peeling

cutting

reblending

filtering

cooking

bottling

finished

Figure 07: Sankey Diagram

Figure 06: Data Flow Diagram

Figure 05: Pie Chart

Input 850 Sorting Loss 17

Peeling Loss 264.6

568.4

491.96

Wa

ter added 300

Juice Spills 32

759.96

Fiber Loss 332

427.96

Sugar 60 Cooking Loss 97.59

390.37

Bottli

ng Loss14.47

Bottl

ed 375

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The width of the arrows is proportional to the size of the represented flow. Sankey diagrams are a better way to illustrate which flows represent advantages and what flows are responsible for waste and emissions.

5.0 Developing the baseline data/information"Baseline" is just the statistically conventional way of saying "starting point". In other words, how are we doing now. It is important to measure the industry performance before making any changes to production processes. If you do not measure how the industry is doing now, then there will be no way to evaluate whether a change is needed to minimize the waste. This initial gathering of data is referred to as baseline data collection. It provides a comparison point to help assess whether a change you make is having the expected impact.

Baseline data can be collected and analyzed for periods as short as 30 days or as long as several years Usually 30 to 180 days provides sufficient data to reveal trends of concern to management. It is often best to create a graph of the data that summarizes the frequency or percentage of what is being measured over time.

When developing baseline data, assumptions may have been made that are not based on objective information. Sometimes this might lead to take wrong decisions on waste minimization. The baseline numbers provide an accurate comparison point for your improvement efforts.

By calculating mass in and mass out, total mass of waste material can be obtained. By doing this, base line of the production process can be derived as follows;

Basis of the data: Per product unitResource consumption: Waste generation:

Material used: how many kg/product unitWater used: how many m3/product unitElectrical energy used : kWhr/product unitThermal energy used : kJ/product unit

Material waste : kg/product unitWater waste : m3/produc unitElectrical energy waste : kWhr/product unitThermal energy waste : kJ/product unit

Table 02 : Baseline information based on material and energy balance

6.0 Costing of wasteThe waste stream characterization consists of three parts:

Quantifying the waste streams (the figures should be obtained from the material balance); Describing the content and the environmental impact of the waste streams; and Assigning costs (e.g. value of lost materials and cost of treatment) of the waste streams.

The cost assignment gives a very good picture of how much money is lost with each waste stream. At the same time such figures creates commitment; indicates the potential of savings; and shows how high investments may be to avoid or minimize the waste streams.

Waste is an increasing problem for businesses in industrial sectors as disposal costs rise, tighter legislation is imposed and it becomes more difficult to find facilities that can accept waste. By analysing the causes of waste within production processes and taking a systematic approach to eliminating them, your business can keep waste problems to a minimum. Reducing waste will cut the costs of buying and processing raw materials, as well as the cost of disposal. It will also help you comply with legislation, improve the public image of your business and open up new markets among buyers for whom environmental awareness is important.

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It is nearly impossible to eliminate all waste from production processes. However, by setting a target of zero waste you can cut it to a minimum. The key is to find out how much waste is costing you and where it is being produced. To do this, you should:

Look at your existing production processes and identify areas where waste is a problem. You could compare raw materials and component purchases with output, look at production or waste disposal reports, talk to relevant managers or operators, or simply walk around your business.

Get additional information from customers or suppliers if necessary. Specialist waste disposal contractors may be able to provide further input.

Calculate the cost of waste. You can base this on straightforward replacement costs or, if production is running at capacity, on opportunity cost (through lost potential sales) - including the cost of labour, packaging and waste disposal.

You might find that it doesn't make financial sense to resolve minor waste problems - eg if one product in 1,000 is faulty, it might not be worth the cost of improving it to one in 10,000. Bear in mind, however, that faulty products affect your image with customers, and this can have cost implications.

7.0 What is CP potential and how to arrive at CP potentialOnce you have identified the sources of waste from production processes, and how much they are costing your business, you should look at the most cost-effective way to reduce this waste. It's a good idea to focus initially on quick wins - things you can do immediately that will reduce waste almost instantly. You might also want to consider quick fixes - putting in place a temporary solution to a problem to give you time to design a more permanent answer.

It is essential to prioritize cost improvements, as making a change to eliminate a problem might not always be cost-effective. The main focus should be on dealing with those problems which are most costly to your business because they will have the biggest impact on your profits.

Firms which aim to adopt Cleaner Production (CP) may take a number of different approaches to identify their technical and organizational options. Experience suggests that frequently, there may be several options which do not require any significant initial capital investments; though these 'low-hanging fruit' opportunities are likely to be limited, and more significant improvements will probably require some initial investment.

The list of proposed cleaner production options from brain storming to eliminate or minimize waste, should be reviewed to identify:

Options that can be implemented directly; Options that needs further study; and Options that can be rejected because they aren't realistic or feasible.

The options that can be implemented directly should be done so. Keep a list of the implemented cleaner production options to document the achievements of the cleaner production work. The options that need further study should be evaluated during the next step.

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