Environmental Waste Management

Lesson Structure

There are 6 lessons in this course:

1. Domestic Waste
   • Definitions
   • The Earths environment
   • Conservation and use of resources
   • Value of resources: economic, ecological and aesthetic
   • Damage being caused
   • Urbanisation
   • The impact of humans
   • Sewage and it's treatment
   • Characteristics of sewage
   • Components of sewage - solids, organic material, industrial waste
   • Decomposition of sewage
   • The nitrogen cycle
   • Classification of sewage systems
   • Storm water systems and management
   • Dry rubbish
   • Nature of refuse
   • Placement and protection of bins
   • Trade waste
   • Refuse collection systems
   • Refuse collection vehicles
   • Salvage materials
   • Safe disposal of household chemicals
2. Street Cleaning & Disposal Of Refuse
   • Types of street refuse
   • Methods of street cleaning - gritting, sanding, sweeping, washing, etc
   • Cleaning storm water pits
   • Managing snow
   • Refuse disposal-separation, controlled tipping, combustion, pulverisation, etc
   • Refuse for fertiliser
   • Methods of refuse Sorting - screening, magnetic, hand sorting
   • Types of incinerators
   • Vacuumn systems for refuse collection - garchey system, gandillon
   • Harvesting energy from combustion
3. Industrial Waste
   • Types of industrial pollution
   • The greenhouse effect
   • Ozone depletion
4. Toxic and Nuclear Waste
   • Nuclear power
   • Nuclear fission
   • Mining nuclear fuel
   • Uranium enrichment
   • Gas diffusion
   • Gas centrifuge
   • Nuclear waste
   • Transporting nuclear waste
   • Reprocessing
   • Health risks of nuclear waste
5. Water Quality and Treatment
   • Industrial effluent
   • Pricing control compared with direct control
   • Types of water impurities
   • Scope of purification
   • Managing water for public supply
   • Water treatment methods
   • Purification methods - sedimentation, filtration, disinfection, aeration, screening, etc
   • Recycling sewage water
   • Recycling waste water
   • Reed bed treatment
   • Improving water quality from any source - physical, chemical, biological impurities
   • Water borne diseases
6. Recycling Waste
   • Scope and nature of recycling
   • Rubbish tips (dumps)
   • Recycling plastics
   • Recycling metals
   • Recycling glass
   • Recycling paper
   • Recycling rubber
   • Actions by individuals (at home or work) - reducing, reusing and recycling waste

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Explain the nitrogen cycle and how it relates to waste treatment.
• Determine the economic considerations of different waste disposal systems.
• Compare industrial waste management with domestic waste management procedures.
• Determine the principles of "polluter pays" legislation and how it is applied.
• Describe how a budget is applied to managing a specific waste management enterprise.
• Discuss issues in nuclear power and nuclear waste technology (including hospital waste).
• Explain the cyclic nature of the water system and its relationship to environmental waste management.
• Monitor and recommend improvements to a specified recycling enterprise.

MANAGING DRY WASTE

This course deals with a wide variety of different types of waste; dry and wet, toxic and clean. Household Refuse is just one of these areas studied.

Consider the Composition of Household Refuse

Household refuse, the waste material from houses and flats, is comprised mainly of:

• Dust
• Cinders
• Ashes
• Vegetable matter
• Paper
• Empty cans
• Food containers
• Rags
• Bottles
• Bones
• Broken glass and crockery
• Old iron

In modern society the variation between the winter and summer content of the refuse is not as great as it was in the days when ashes and cinders accounted for a much larger share of the refuse. Before any scheme of refuse disposal is prepared, proper analysis by weight of actual refuse should be taken. Such analyses help to establish the value of any material that can be salvaged (recycled), and the percentages of combustible or material that can be composted, contained therein. It has been estimated that in some cases up to 80% of our household wastes could be composted or recycled, but this rarely occurs and as a result household waste is usually a significant component of the total amount of waste being added to our landfills.

For example, The Environment Protection Authority (EPA) in Victoria, Australia estimates that the amount of waste produced by Greater Melbourne alone could fill the world famous Melbourne Cricket Ground (which can seat around 100,000 people) to the top of the highest stand every 8 weeks. The cost to residents of the collection, transportation and disposal of this waste is at least $300 million dollars a year.

Of the total waste stream at landfills in Victoria (for example) around 35% of the wastes are from domestic sources. This included:

• Packaging waste (7.8%) of total waste
• Food (10.9%)
• Garden (7.1) - this amount in domestic waste collections
• Other paper (6.7%)
• Other garbage (2.9%).

In addition another 13.8% of the total waste stream was from gardening waste delivered privately to the landfills. Much of this waste is easily composted or could be recycled.

The City of London produces 1.1 tonne (approximately) of waste per household, municipal waste making up 26% of total waste in that city. It is also interesting to note that of the recycling waste collected 97% is reusable. Yet there are still many items thrown out that end up in landfill sites; in the UK 1.5million computers are dumped in landfill sites annually. It has been estimated that over 90% of what is actually thrown into their bins is reusable.

The City of New York with a population of 20 million produces 11,000 tons of residential and institutional refuse and recyclable waste each day. The solid waste issue created major public concern and this alone has reduced the daily waste from 13,000 tons a decade ago. A further 13,000 tons of waste is also generated by industry. During the late 1980’s over two-thirds of the landfill sites in the USA closed. This created further public interest in the incineration, recycling and waste transport programs that have taken their place. It has been estimated that most of the solid waste collected daily is made up of food scraps! Further interest is now being generated by state, local and federal government in how the waste will be treated in the future e.g. the centralised composting of the majority of these materials.

The Nature of Refuse

The nature of refuse has undergone many changes in the last few decades. The decline in consumption of coal, and the increasing use of electricity and natural gas has reduced the necessity of removal of cinders and ashes from the home, although this may change again with current trends to the installation of combustion heaters (mainly using wood as a fuel), and a return to the use of open fireplaces.

During the same period vegetable matter content has varied very little. In some areas the amount of garden refuse has increased, but the greatest change due to the increased use of packaged goods, especially plastic bags from supermarkets.

This tendency towards increases in overall household refuse has made the standard sized garbage bin inadequate. Many municipalities have introduced the larger plastic bin with the hinged lid. Many municipalities also provide a recycling service - some providing separate bins or containers in which to place recyclable materials.

The Placement and Protection of Bins

Bin placement is an important concept. Bins should be placed in a position where they are readily accessible from the house in order to avoid long carries of waste, with the consequent waste of time. The bins, which have wheels, and are being increasingly used by many municipalities, are ideal, because they allow the home owner to keep the bins within their property, and it is a quite easy manner to roll them out on collection days.

It is desirable to protect the bins against the weather, because lids could be left off or be displaced by cats or dogs. It is also possible that the bin may be distorted so that the lid does not fit properly. An ideal arrangement is to provide a covered alcove which forms part of the building, and is accessible under cover from the house. As an alternative, a small dustbin shed could be built.

A covered position has the advantage that if refuse is placed on the ground beside the bin, after the bin is full, it is then protected from the elements. It will not be dampened by the rain, and it will not be blown away. However, many people with private property keep their bins in the open. This allows the contents to be wetted by rain. This can produce rapid decomposition of the refuse, causing foul smells.

Trade Waste/Refuse

Trade refuse can be defined as the refuse of any trade, manufacture or business, or any building materials.

It may be regarded as any useless material or waste that is produced in the course of manufacturing or other operations that are carried out for profit, and not being of domestic waste in nature.

In urban areas the local authority usually removes all house refuse. Each property owner pays an amount towards these collection costs as part of their annual property rates. It has generally been considered by many municipalities that refuse of a domestic nature produced by hotels, restaurants, and other catering establishments is house refuse, and is therefore removed by the local municipality (or their contractors).

On the other hand trade refuse is normally subject to a charge for its removal. It includes a wide range of materials, such as:

• Ashes
• Clinker
• Wood refuse
• Packing material
• Fruit refuse
• Vegetable refuse
• Fish refuse

Local authorities may be under no obligation to remove such refuse, but they usually do so in view of the highly offensive nature of much of the refuse when it is kept too long. When large factories, markets, etc. are concerned the daily collection of refuse may become a necessity.

Many local authorities collect garden refuse free of charge, if the refuse is placed in special plastic bags or tied in bundles. This service is separate from the normal refuse collection, and generally occurs on a set number of days each year. In addition local council or other government authority may also have special hard rubbish collection days, where hard waste, such as old refrigerators or building materials will be collected. There are generally strict conditions placed on the types of materials, and the size and weight of materials to be collected. The cost of these "special" or "extra" collections is generally covered within the waste collection component of the annual property rates.

The Collection of Refuse

The collection of household refuse is normally carried out by the local authority, either using labour directly employed by them, or increasingly by using contractors. Disadvantages of using a contractor may include:

• Close supervision may be required to ensure that the work is done in an efficient way, and that the bins are left in a clean state.
• The employees of the contractor may be paid according to how many bins that they empty, and so tend to sacrifice cleanliness for speed.
• In some countries when traditional bins are used, the collection and emptying of the bins is often done in one of the following two ways:
• Two men go ahead and bring out all of the bins on to the pavement. The dust wagon follows about half a street behind and the bins are emptied by two men working behind the vehicle. Finally one man brings up the rear, and takes the bins back to the premises.
• A gang of men work with the vehicle and each man is responsible for obtaining a bin, emptying it and returning it.

The second system is the better because it obviates two disadvantages that occur in the first method. These disadvantages are:

• When the bins are standing in the street, the lids can be removed by children, scavengers, etc. This allows the contents of the bins to blow about.
• There is a possibility that the bins may be returned to the wrong premises.