Chapter 4: Recycling of Materials

Introduction Recycling of Materials

Have you ever imagined a world without decomposers, bacteria and fungi? Of course you will assume a world without diseases since bacteria and fungi are potential causative agents of many diseases. However, what would happen to the accumulation of wastes in the environment? What about treatment of water?
You shouldnt forget that bacteria are important in the decomposition and treatment of water.
Do you know that waste materials like used water bottles can be used to build a strong building? Figure 4.1 shows one of the most beautiful structures which was built using used plastic bottles.

Figure. 4.1: Plastic bottle construction
In this chapter you will appreciate how vital substances are recycled to maintain life in nature and by man.

4.1: Natural Sources of water
Where do you get the water you use for drinking at home? We obtain the water we use at home from many sources. Some of these sources are natural and others artificial. Figure 4.2 represents the major natural sources of water in Uganda.

Activity 4.1: Discussing the sources of water as a natural resource, its importance in everyday life.
What you need: charts or sheets of paper, note book, pen, stylus, slate, Perkins brailler, Braille papers

What to do.
In a small group;
Look at the pictures in Figure 4.3, then answer the questions that follow:

1. Other than the sources shown in Figure 4.3, list other sources of water existent in your community?
2. Describe how water is useful to you and/or the community.
3. Present your work to the class.
4. Individually write or braille the class conclusions in your notebooks.
   In Activity 4.1, you have been able to identify the different natural and artificial sources of water in our communities. You now have a role to conserve and protect them.

Properties of Water
About 65 % of the human body is composed of water. Water is essential for the survival ot life on earth and we need water for almost everything; for example drinking, bathing. and cooking. Water has unique properties which contribute to its use for certain functions. For example, water is used as a habitat for animals because it has oxygen necessary for life, its a lubricant and transparent therefore allows light to pass through. In Activity 4.2, you will discuss the various properties of water.

Activity 42: O.scuss.ng the physical and chemical properties ot water
What you need: notebooks, stylus, slate, Perkins brailler and braille papers.

What to do
In groups;
Study pictures A and B in Figure 4.4.

1. Name the property of water which is illustrated in pictures (A) and (B).
2. Explain the significance ofthe above property tothe survival of living organisrns.
3. Other than the property illustrated by (A) and (B), state other chemical and physical properties of water.
4. Explain the significance of each of the properties in (2) and (3) above.
5. Present your findings to the rest of the class.

4.2: The Sun and Water Cycle
The sun is the major natural source of energy to the earth and drives the water cycle as well. A cycle means something which is repetitive. For example, in this case, the water cycle involves the processes of formation of water and conversion of water into different forms. By doing Activity 4.3, you will understand more about the water cycles and the role of the sun in the water cycle.

Activity 4.3: Describing the water cycle and role of the sun in the water cycle.
What you need: Manila charts, notebooks, stylus, slate, Perkins brailler and
braille papers.
What to do:
In groups, look at the water cycle given and answer the questions that follow.

1.Copy Figure 4.5 onto your group manila chart and use it to describe how water cycles work?
2.Explain the role of the sun in the water cycle
3.Present your work to the rest of the class.
4.Individually write the class conclusions in your notebooks.
In Activity 4.3, you have discovered the different processes involved in the water cycle. You have also realized the importance of the sun in the water cycle.

4.3: Sewage Treatment
Water can be recycled from the waste water for example sewage.
Look at Figure 4.6, it summarizes the process of sewage treatment.

In any society sewage is a serious environmental issue due to the waste- water and the bio-solids/ sewage sludge contained in it which causes health

problems to people and animals. Therefore, it is every one’s concern to treat sewage in order to avoid its dangers. By doing Activity 4.4. you will discover sewage is treated to levels that are environmentally safe.

Activity 4.4: Discussing the process of sewage treatment

What you need: notebooks, stylus, slate, Perkins brailler and braille papers.
What to do:
The article below was published by the office of the auditor general about management of sewage in urban centres. Study it in groups.
Sewage treatment. The principle objective of sewage treatment is to allow human and industrial effluents to be degraded and disposed off without danger to human health or unacceptable damage to the natural environment.
NWSC uses mainly two methods to treat sewage: Conventional and non- conventional methods.
Conventional methods are a combination of both physical operations and biological processes to degrade and remove solids and harmful nutrients from the sewage.
The non-conventional- This uses biological processes that mainly take place in the stabilization ponds to remove harmful nutrients from the sewage.

Sewage treatment by conventional methods; When the raw sewage reaches the treatment plant. it undergoes preliminary treatment which usually is done by directing the waste water/ raw sewage through a series of screens and strainers to remove any floating materials (for example rugs, plastics, paper, wood, and polythene) that may have come along with it.
The sewage is then channeled to sedimentation tanks where it undergoes primary treatment. Primary treatment allows sludge and other heavy solids to settle down and allows light materials, including grease and oils, to rise to the surface where they can be removed through a process known as skimming.
The sewage then undergoes secondary treatment using both aerobic and anaerobic processes. Anaerobic bacteria degrades the sewage by feeding on the nutrients which are dissolved in the absence of oxygen. The sewage then undergoes aerobic degradation where it is passed over stone or plastic media that is grown with bacteria. algae and other micro-organisms. Aerobic digestion can also be done by passing the sewage in an aeration tank where it is vigorously mixed with air to provide oxygen for aerobic organisms for several hours to allow the bacteria break down the organic material. After this stage, the sewage undergoes tertiary treatment to continue the purification process before discharge to the environment.
Treatment process by conventional methods involves the use of machines such as: aerators, trickling filters, bio filters.

Non-conventional methods treat sewage by using mainly stabilization ponds. There are mainly three types of ponds: the anaerobic ponds, facultative and maturation ponds. Raw sewage is channelled through filters to remove any solid The sewage undergoes anaerobic digestion where anaerobic bacteria feed on the organic nutrients in the absence of oxygen. This process takes 2-3 days and
reduces up to 80% of the dissolved nutrients.
After anaerobic treatment, the sewage is then channeled to the facultative pond which has both anaerobic zones (deeper parts in the pond) and aerobic zones (close to the surface) where there is continued degrading of the waste-water by the bacteria and other microbiological organisms that keep feeding on the contents of the sewage. At this stage, the sewage undergoes both anaerobic and aerobic
processes which help further degrade the sewage. This process usually takes 5-10 days. The final sewage treatment process is maturation and takes place in the maturation ponds. The maturation process is aimed at killing and removing the anaerobic and aerobic bacteria including any other pathogens before final discharge to the environment.

Effluent(liquid part of sewage) discharge to the environment; once the sewage has undergone treatment it is discharged to the environment. Discharge is usually into wetlands for continued purification before joining major water sources. The method of discharge and quality of the effluent must meet the discharge standards set out in the discharge permits granted and other environmental regulations in place to avoid pollution of the environment and contamination of potential water sources.

1.Using Figure 4.7 and the article above, summarise on a manila how sewage is treated to reach safe levels for discharge.
2.Present your work to the rest of the class.
3.Write individual notes from the class conclusion.

From Activity 4.4, you have learnt the process of sewage treatment, and the level at which the sewage is considered safe for discharge.

4.4: Water Treatment
It is extremely harmful to drink contaminated water.
It is always good to use treated water because in our natural environment water is always contaminated. The impurities in untreated water are harmful to one’s health. Water treatment removes or reduces the concentration of contaminants hence making the water safe for a specific end-use.

The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including water safely returnedto the environment.
How then does water get treated? By doing Activity 4.5, you will discover how water is treated.
Activity 4.5: Discussing the process ot water treatment

What you need: notebooks, stylus, slate, and Perkins brailler and braille papers.
What to do:
The information below summarises the steps involved in water treatment in a water
treatment plant, as shown in Figure 4.8. (The steps are not in their correct order)
A: Chlorination: Is added to kill germs and bacteria.
B: Fine sand filtration: Removes very tiny particles.
C: pH correction: Are alkaline granular materials used for elevating pH of water after treating it with chlorine. Chlorine added to the water kills the germs, however leaving it acidic. Substances such as calcium carbonate or magnesium oxide must be added to make the water neutral again.
Screening: Screening is the removal of floating debris (leaves, feaces).
E: Flocculation: Is a process in which colloids come out of suspension in the form of floc or flake, either spontaneously or due to the addition of a clarifying agent such as aluminium sulphate.
D:F: Coarse and filtration: Uses coarse materials to do further filtration to remove bigger particles, for example, logs, sticks.

Task:

1. Arrange the steps(A, B, C, D, E and F) in their correct order.

Project Work
Activity 4.6: Diesigrmng a water treatment model using locally available materials
What you need: hotebook, stylus, slate, Perkins brailler and Braille papers.
What to do:

1. Design an experiment to obtain clear water from muddy water, using sand,charcoal, small stones, empty plastic bottle, and course materials.
2. Present your work to the rest of the class.
3. Individually write class conclusions in your notebook.
   Application of Action of Putrefying Bacteria
   Putrefying bacteria are bacteria that cause decay of living matter. They carry out
   decomposition of organic matter hence recycling nitrogen from dead organisms.

Activity 4.7: Applying the action of putrefying bacteria to the treatment of pit latrines
The advert below shows the information about a putrefying bacteria containing
product. It is used for pit latrine treatment. Use it to answer the questions that follow.

1. From the advert above, describe the role of putrefying bacteria on the
   treatment of pit latrines.
2. Present your findings to the rest of the class.
   4.5: Carbon Cycle
   Carbon is a life sustaining element found in soil, living organisms and atmosphere and are very essential in the lives of all living things. Since carbon is the main building block of most food nutrients, there is need to recycle it to be reused whenever it is lost from the living organisms, thus carbon cycle involves inter- conversions of carbon in the earth and organisms and back to the atmosphere.
   In activity 4.8, you will discuss the carbon cycle and its importance.

Activity 4.8: Describing the carbon cycle
What you need: notebooks, Stylus, slate, Perkins brailler and braille papers.
What to do:
In groups;
Study Figure. 4.10 about the carbon cycle and use it to identify the components of the cycle.

I. Using Figure 4.10, describe the carbon cycle.

2. What is the importance of carbon cycle to your community.
3. Present your findings on a manila paper.
4. Individually write the class conclusions in your notebooks.
   The activity must have made you understand and appreciate the carbon cycle concept, and it’s importance to our community.
   4.6: Fungi and Bacteria in Decaying Organic Materials
   Fungi and bacteria are microorganisms which decompose dead organisms like the ones shown in Figure 4.11 and Figure 4.12. This allows the immobilisation and recycling of nutrients in the soil.

What you need: Manila cards, markers, notebooks, braille paper, stylus, slate, Perkins brailler. internet, computers, and decaying tree.
What to do.
In groups:

1. Discuss the role of bacteria and fungi in the decay of organic materials.
2. Describe how carbon is exchanged among different organisms in the
   ecosystem.
3. Present your group contributions to the class.
4. Individually write the class conclusions in your notebooks.
   4.7: Organic Fertilisers
   The word organic means a substance containing carbon. Did you know that fertilizers can be derived from organic material. Can you identify any organic material in your community which can be used to make fertilizers? Animal excreta/ manure, human excreta and plant matter; for example, compost (decaying organic material used as fertilisers for growing plant materials) and crop residues) are some of these organic material.
   In Activity 4.10, you will mainly focus on preparing organic fertilisers from plant matter.

What you need: notebooks, braille paper, stylus, slate, Perkins brailler, internet and computers.
What to do:
In groups:

1. wrrte or braille down a procedure on how to prepare compost container to make some organic fertilisers, using plant materials.
2. Present your procedure to the rest of the class and make necessary adjustments.
3. Construct a compost container from locally available materials such as sticks
   and fill it with organic wastes such as banana peelings, coffee, husks, tea
   bags, maize leaves etc., then leave the waste to decompose
4. Individually, write a report about the steps you went through constructing a compost container.
   4.8: Nitrogen Cycle
   Plants are green because of nitrogen. Your DNA is composed of nitrogen.
   Nitrogen is an important part of living organisms. Just like carbon, nitrogen is also recycled. In Activity 4.11, you will describe the nitrogen cycle and discuss its importance in our environment.

Activity 4.11: Describing the nitrogen cycle
What you need: notebooks, stylus, slate, Perkins brailler and braille papers.
What to do:

In groups; Study fig
4.13 and answer the
questions that follow;

1. (a) From figure 4.13, Identify how nitrogen is taken into:
   (i) Air (ii) Soil
2. (b) Describe the nitrogen cycle.
3. Explain the importance of the nitrogen cycle in our community.
4. Farmers most often add fertilisers to the soil to improve plant growth. Explain the effects of adding excess nitrogen based fertilisers on: a)Nitrogen cycle b) on water bodies.
5. Present your group contributions to the class.
6. Individually write or braille the class conclusions in your notebooks.
8. Nitrogen is an important part of nutrients such as amino acids, proteins even our genetic material (DNA) thus a constituent of many cells and processes. It is also needed to make chlorophyll in plants, which plants use in photosynthesis to make their own food. which sustains life of all organisms in nature.

Nitrogen Fixation and Loss in the SOIL
As noted in the Activity 4.11, nitrogen plays different essential roles in our lives. Therefore, there is need to understand how it is fixed into and lost from the soil.
Soils which are deficient in nitrogen are considered highly infertile. In Activity 4.12, you will understand the ways in which nitrogen is lost and fixed into the soil.

Activity 4.12: Analysing processes by which nitrogen IS fixed and removed from the soil
What you need: notebooks, stylus, slate, Perkins brailler and braille papers
What to do:
Basing on Figure 4.13; in groups:

1. Write down the symbiotic and non-symbiotic ways of nitrogen fixation.
   2, List the ways through which nitrogen is lost from the soil.
2. Individually write the class conclusions in your notebooks.
3. State the effects of nitrogen loss in the soil to the survival of other living organisms in the ecosystem.
4. Present your group contributions to the class.
   Hint: Symbiotic is a close relationship between two species in which at least one species benefit while non-symbiotic both organisms and live freely.
   The activity must have made you appreciate the symbiotic and non-symbiotic ways of fixation. There are different ways how soil obtains nitrogen and also loses it. All these processes lead to a balance in the nitrogen content in the universe.