Public Health Engineering In Civil Engineering

pages Pages: 4word Words: 890

Question :

Hong Kong College of Engineering

Code: B3C30

Write the title on "Public Health Engineering in Civil Engineering".

Task 1:

Explain how below ground drainage systems are used to dispose of foul water from buildings.

Task 2:

Explain how below ground drainage systems are used to dispose of surface water.

Task 3:

Explain how domestic sewage is treated.

Task 4:

Describe the methods used to dispose of solid domestic waste.

Task 5:

Describe the stages of the process used to purify and store drinking water.

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Answer :


In this current assignment the researcher represents and describes about the ground drainage system and various procedures and steps which are followed in order to treat domestic sewage. The waste materials which are generated from domestic household is hazardous for life of the human being and aquatic living being. Therefore the solid waste needs to be dispose properly so that it does not cause any harm to the life of living. In the first part of the assignment the researcher discusses about the disposal of foul water from buildings by using ground drainage systems in Hong Kong. In the second part of the assignment the researcher discusses about 1the disposal of surface water by using ground drainage systems and various methods used for household waste disposal. In the end part of the assignment the researcher going to discuss about the various stages and process which is used to purify and store drinking water. In order to solve the various issues and problems of the people the government of Hong Kong formed a committee that work jointly with Civil engineering department. The government of Hong Kong must also increase the awareness about the various impacts of improper disposal of domestic waste. 

Task 1


 Explanation of disposal of foul water from buildings by using ground drainage systems

1. Usage of the below ground drainage system to dispose of foul water from building


The foul drainage system is constantly creating problems below the ground drainage systems that are mainly disposed of foul water from buildings. In the buildings there is a high necessity to maintain the foul system that arises from the flushed water of toilets or basins. This water basically traps on that areas and make the passage of wastage water difficult. In order to reduce the foul water from buildings there is a high necessity to maintain a ground drainage system in the foul drainage in the toilet areas. Moreover, there is a high necessity to maintain surface water of drainage that basically deals with rainfall. The ground drainage system helps the foul water to get collected in proper sequences. There is a high necessity to maintain a proper design of ground drainage systems to make the foul water disposal from the buildings (Asami, Katayama, Torrey, Visvanathan, & Furumai, 2016).  



The important components of a drainage system in a house are the bathroom, sinks, wash basins the people living in the house use all these components which results in formation of wastewater. The wastewater from all these components is drained into the municipal sewer. This type of drainage system is called Housing Drainage system. Thus it is important that proper system is maintained for the wastewater from these components. Before going into the drainage system it is important to know the type of wastewater that is being generated through all these components. The wastewater generated from these components are domestic are likely to be less harmful in compared to the industrial wastewater. There are systems which help in disposal of this wastewater like plumbing system. The Plumbing system is a whole system containing pipe line providing water supply and also to help in the disposal of the wastewater from the building. In this system there are various elements like sewer which carries the waste water, the soil pipe which carries the sewage from the W.C, waste pipe carries the sludge from bathrooms. The Sewerage system is also a system which comprises of all the types and sizes of wastewater from the whole town and city and carries it to the wastewater treatment plant (Babaei,et al. 2015).

There are RCC and masonry chambers constructed in between suitable intervals along with e sewer line to facilitate proper drainage. The drainage in of the bathrooms and other components are done through traps which are the fittings which are at the end of soil pipes and help in preventing the foul gases of the waste and soil pipe (Charlesworth,  Faraj-Llyod, & Coupe 2017).  

The following steps are carried out in a proper ground drainage system to dispose foul water:

  • The drainage is laid by the side of the building for easy maintenance.
  • The joints in the sewer are made leak proof.
  • The wastewater flows with force of the gravity.

Rodent Control: Special care of the sites must be taken in order to control the rodents. The various measures which include the followings:

  1. Sealed Drainage: is the system which covers the pipe work in the inspection chamber instead of open channels 
  2. Intercepting: Intercepting traps which requires frequent maintenance and are susceptible to the blockage. The traps are build on stopper technologies which permits locking types and provides easy accessibility from the surface.
  3. Rodent Barriers:   These devices are used in order to prevent the entry of the rat in the sewage system.

value and potential of player


2. Calculations:

Calculations to determine quantity, velocity and depth of flow, pipe size and gradient of below ground drainage 

The calculation for the quantity of water can be related to the formulae below

Q=(A x R x P) / 3600= (100000 mm x 30000 mm x 150mm/hr x 0.875)/3600+ 109375000 mm3/hr

ii) Gradient of pipe= u* du/dy

0.01* (1.5m/s/ 100m x 30m)

0.01*0.0015= 0.000015 m3/s

The above answer can be related to the gradient of the pipe through which the water shall flow The calculation for determining the size of the pipe can be related to the following formulae

Q= (V x A) = (1.5m2 x 100m x 30m) = 4500 m3

Chezy formula

F = (16/Re) x μ

Re = ↻ x v x D

Re = 1000 kg/m3* 0.8 m/s* 300mm= 240000 mm3/s

Therefore, it can be well said that the result in this part is given above

  • Evaluation of the standard methods to be used to test, inspect and maintain below ground drainage in Hong Kong:

It is not adequate to construct a prudent drainage system associated with proper sewage treatments, but it is also imperative to evaluate the alignments of the apparatus as well as the accuracy of the gradients in order to sustain with the prevalent system. On that note, several analytical frameworks can be exercised with the potential to inspect and maintain the underground drainage system. One of them, obviously, could be measuring water tightness.

Water tightness can be illustrated as the ability of the drainage system to withstand water pressure. The analysis of water tightness is executed immediately after backfilling of trenches and consolidation of lied paths.    

size of pipe

correlation of price and quantity

            Air tests- Standard dimensions of the components of the apparatus is as follows:

  1. Diameter of the Pipe- 300mm
  2. Water Pressure- 110mm water gauge
  3. Time of stagnation- 5 min
  4. Initial Pressure (Air)- 100 mm gauge
  5. Maximum loss of manometric head- 25mm

Water Tests- Standard dimensions of the components of the apparatus is as follows:

  1. Diameter of the Pipe- 300mm
  2. Elevation- 5m (lowest invert of the test section)
  3.  Depth- 1m (highest invert of the test section)

 Task 2


Underground drainage system is usually concerned with the disposal of unwanted water that can be accumulated by natural or artificial means. This concern principally deals with two major sources of unwanted waters that can be respectively termed as surface water and foul water. Individual hygiene and other cleaning-oriented purposes usually generate waste waters that can be termed as foul water and claims drastic steps of disposal since it is a potential threat for health related issues and may pave the constructional fabrics towards collapse. On the other hand, accumulated rainwater can be cited as the origin of surface water that usually stagnates on roofs and other hard surfaces and own a potential to damp the constructional fabrics and create an unhygienic ambience (Zhou, 2014).

Effective disposal is usually accomplished by drawing the wastewater in underground aquifers with the aid of certain channeling systems. A combined system of such sorts consists of a central duct that is supposed to convey the disposals. Auxiliary expertise such as Air Inlets and Ventilating Pipes are usually mounted on the duct in order to ensure zero atmospheric exposure. Proper calibration usually comes with a burden of disintegrating the blend of disposals, whereas, in Totally separate systems, two of the each sources of water is advocated by two separate pipes towards sewage treatment. Zero atmospheric exposure, hereby, is ensured only for the foul water since surface water is inherently free from such lethal odors. Partially separate systems introduce a dimension of compromise with the other two predefined drainage systems since one of its two consisting ducts usually conveys an eclectic blend of disposals with foul water as solvent. 

This system facilitates the sewage system by transcending the design constraints such as ineffective soakaway or dearth of regional watercourse. In addition to that, underground soakaway is the driving component of Outlets that enables the system to filter the discharge directly. In case of Outlets, the rate of discharge needs to be conditioned as per the provision of detention basins. Drainage systems need to be evaluated in order to preserve the performance and enable the drain to cope with the backfilling of trenches. The tests are distinguished on the grounds of their pursuits and can be broadly categorized as Alignment Test, Obstruction Test and soundness test (Mugume, Gomez,  Farmani & Butler 2015).

  • Alignment Test- This test is usually conveyed to ensure the proper alignment of the ducts which should maintain a parallel and straight orientation in order to acquire the satisfactory gradient.

 Mirror Test, as a means of accomplishing proper alignment, is usually carried out with the aid of mirrors and a coherent source of light and the entire apparatus herald the light towards deviation caused by the angled mirrors. This deviation alarms the observer with an awareness of any hindrance inside the pipe or it indicates sheer misalignment of the apparatus. Proper alignment of the system endows the observer with a solid orb of light.

Torch Test is usually carried out to ensure the horizontal countenance of the bore of a drainage system by means of an electric torch which is supposed to indicate every anomaly in the alignment.

  • Obstruction Test- This test is conducted in order to detect the obstruction or misalignments in joints.

This test is aided by a steel rolling ball (purpose-made) which is inserted through the principal duct of the drain. The ball is supposed to indicate proper alignment and precise gradient if it maintains an unimpeded trajectory throughout the duct.

  • Soundness Test- This test is usually conducted on prevalent as well as new drainage installations. Most of the regional authorities in Hong Kong rely on the drains only if they are approved by any hydraulic test (usually with a head of 1.5m). The Inspection Chambers are usually replenished with water in order to fathom the soundness. New installations are subjected to these tests twice; before the backfilling of the existing trenches and immediately after the consolidation of the laid paths.       

A flat head of 1.5m is the pivotal requirement for a hydraulic test that is maintained at the peak point of the specific section of concern. The lower end of the drain is plugged off afterwards followed by an act of replenishment of water by the means of a hose pipe in order to accomplish the required head. In this course of experiment, zero atmospheric exposure need to be ensured and this can be accomplished simply by introducing a tiny hose (made of rubber) into the trap (and through the crown of the gully as well). When the system is charged up to its capacity, it is allowed to stagnate for a specified (usually 2 hours as per BS 8301) period of time. If this stagnation is followed by a significant deviation of water levels it usually suggests the presence of porosity of joints (in pipe, yarn or sand and cement). If the system proves to be sound, only the cap needs to get removed from the expanding plug at the datum of the drain under experiment which facilitates the release of the significant domestic pressure. This system is prescribed not to be dispensed against freezing circumstances.

The pneumatic test (also known as Air test) usually uses a smoke machine to push the air inside the dome until it reaches its highest volume. The outcome of a Pneumatic test is inadequately reliable since it is difficult to monitor subsequent leaks. The method usually introduces soap solutions to each of the joint until the particular leak is tracked. Moreover, the decline in the altitude of the dome usually indicates potential leaks and indulges the observer to pump more air into the system in order to attain the visibility of the leak. Sealing the open ends and charging all of the water seals are the imperative criteria the observer needs to satisfy before implementing a pneumatic test. The test piece is mounted with a hand pump and a hose that is consequently inserted through the trap of the enclosure and two respective valves of the three-way test apparatus are allowed to open. After that, the air is pushed into the system and periodically checked until it reaches the desired test pressure and rest of the alternate valves has been opened. The subsequent air pressure has been immediately accounted by the means of an U-gauge. Afterwards, the system is allowed to stagnate for a prescribed (usually 5 minutes as per BS 8301) interval. The index of pressure should drop to zero if there is any significant leak and the manometer will sustain a uniform difference of levels if the system is sound throughout.

Maintaining drains and following sewage measures are potentially hazardous and may cause lethal circumstances. As per the affiliated documents of H- Drainage and Waste Disposal (with further amendments in 2010), proper safety regulations should be abided along with instructions of performing in enclosed quarters. Relevant permits needs to be issued conditionally where the workers have the possibility to expose thyself into fatal consequences. There are several other statutory obligations which need to be followed before laying into excavational activities. A kit consisting of several equipments that ensures the individual immunity of the worker needs to be provided and this kit is addressed as Personal Protective Equipment (PPE) in industrial dialects. Apart from that, the worker must own a sound knowledge about the tools and their maintenance. 

The kit usually consists of;

  1. Steel toe cap
  2. Safety helmet and boots
  3. Safety vests with illuminative aptitude
  4. Anti-glare glasses
  5. Disposable respirator
  6. Harness and other Fall arresters
  7. Gloves
  8. Ear muffs
  9. Handy gas detectors
  10. Resuscitator
  11. Audio-visual alerts      

 Task 3


Explanation within a short report:

Sewage treatment is one of the major considerations for proper management of the sewage system of an area. Therefore, the municipalities take up a number of functions that are engaged with treatment as well as disposal of domestic sewage. Domestic sewage mainly refers to the water that is extracted from the kitchen, sinks, wash basins and toilets of a household. Therefore, these are the waste water that consists of greater amount of detergent or soap residue. It needs to be treated well before they are disposed off. Under the building regulations [40(1), 40(2), 41(1) and 90] it has been specified that usage of septic tank & cesspool in disposal of foul water from the buildings can be approved only when there is no public sewer in the nearest vicinity of the area. Therefore, in all other alternative cases, the sewage treatment plant requires to be functional (as per the Building Regulations). 

However, it has also been specified that a small sewage treatment plant is allowed to be constructed only when there is no other alternative available. The main points of concerns for Environmental protection Department with small sewage treatment plant are its lack inadequacy in the process of treatment as well as the uncertainty that might rise during long term efficiency of sewage treatment through such small treatment plants. Such cases might lead to discharge of substandard effluents at the outlets.

The process of treatment of sewage in a sewage treatment plant includes four steps. The first one is preliminary treatment followed by primary treatment. The next step is secondary treatment and the last one is tertiary treatment.

  • Preliminary treatment: It involves the removal of grit and gravel from the effluents. This is majorly done by screening of large solid particles. Solids particles within the sewage water that are larger than 6mm in diameter are removed by this process of treatment. 
  • Primary treatment: This step is carried out as an important part of the domestic sewage treatment. This part of the sewage treatment involves settling down of the large suspended particles in the sewage water. These are generally the organic matter that are mixed with the sewage water generated from domestic purposes. The complete primary process includes certain sub processes. These are screening, removal of grits and finally sedimentation of the smaller particles that are essentially the particulate matters in the sewage water. Here in this process the suspended solids and other solid wastes are removed from the sewage water. The efficiency of removal of Total Suspended Solids (TSS) by this process is about 70%. The BOD (Biochemical Oxygen Demand) of the water that is extracted after is process is about 30%. However, while talking about the primary treatment of the domestic sewages, there is another sub treatment (Chemically Enhanced primary Treatment) that is often taken into consideration depending upon the activities taking place in a particular area.
  • Chemically Enhanced Primary Treatment: Few chemicals such as Ferric chemical or alum is added to the water while it passes through this phase. This enhances removal of BOD (Biochemical Oxygen Demand) and TSS (Total Suspended Solids) from the water. This process attains a removal efficiency of TSS by 80% and BOD by about 60%. Therefore, it can be specified that the removal of these two entities of water is a bit more efficient through this process. 
  • Secondary treatment: This process of treatment is carried on in order to have a biological breakdown of the water. Furthermore, this process also helps in reduction of residual parts of the organic matter in water. After the primary treatment, this process is used where there is application of biological treatment process. Within this process, the organic matter that has been settled down at the base of the water is treated and decomposed by the microorganisms in this biological treatment process. The water standard that is met by this process of treatment is 30 mg/L of Total Suspended Solid (TSS) and 20 mg per liter of the Biochemical Oxygen Demand (BOD) of the water (Morón et al 2016).
  • Tertiary treatment: This process is carried on in order to address various kinds of pollutants present within the water. This stage of treatment is the highest level of treatment as well as the final one before the water can be reused, recycled or discharged into the environment. The tertiary treatment process highly improves the quality of the wastewater as when treated by this process. This kind of treatment also polishes the effluents that are the remnants from the secondary process of treatments. The tertiary process comprises of combination of both the physical as well as biological process of treatment. The main objective of the tertiary process of treatment is to remove any remnant nutrient (inorganic compounds) as well as any suspended solids within the sewage water. Other kinds of substances such as phosphorus and nitrogen are also removed through such kind of treatment procedures. This process of treatment makes considerable use of chemical compounds such as alum. It efficiently removes any residual phosphorus within the water. In case, there is any persistent of solid particles in the water, these are also removed during such process of treatment. The waste water from the biological reactor is flown within the IDAL and then to a pumping station. Here the water is met with a flash mixer. The main purpose of the flash mixer is to mix the Alum with that of the wastewater. After such addition of Alum into the water, the tiny particles present in the water turns into floccules. These are the tiny masses of the impurities that are present into the water. Hence, the floc is trapped by the sand at the time of gravity feeding of the clear water during the passage of the water through the chlorine tank. There is another utility of the chlorine tank that is to disinfect the water after all kinds of process of treatment (Cheng,Liao,  Lo, & Peng, 2017)

  Representation of sewage treatment

Figure 1: Representation of sewage treatment

Flow diagram of sewage treatment plant

                                    Figure 2: Flow diagram of sewage treatment plant


Location: Sewage treatment is the process of removing the contamination from the wastewater. STP is a large scale producer for the treatment of the waste water . Therefore for the small development the installation of STP this cannot be made. The sewage plant is generally located in outskirts locations.

Design: The STP which consists of an submersible pump, general headroom, artificial ventilation, access walkways, ladders, open mesh flooring are the basics requirements of the design plan for a general STP.  The details of stated designs structure follows:

Pump: Portable submersible pump are provided for recycling the effluents of the plants.

Headroom: Headroom is required for underground sewage treatment plant.

Artificial ventilation: Artificial ventilation which has been made especially for an enclosed STP. The height of the ventilation pipe should be less than 1m.

Access walkways: The sewage treatment plant access walk way which is made of a minimum width of 0.75 cm. The access walkway is made of stainless steel safety rails and toe boards. In order to prevent  the cross fall must be laid to 1:25 ration.

Ladders: The stainless steel ladder which must be provided for easy access.

Open mesh floorings: Stainless steel ladders which are generally used for the flooring purpose with a uniform load of 5KPA


Methods of operation : The sedimentation tank which are either rectangular horizontal flow tank or square upward flow tank. The tank which should be provided with 60 degree hopper slopes for convenient sludge and collection removal. 

Sizing based on population: The sizing of the plant which is based on the understand parameters.

Disposal of sludge: The sludge which is removed everyday by using the sludge pumps, airlifts, or valves. In addition to this a scum and sludge removal device with adjustable control should be provided.

Disposal of water after treatment: The effluent which is treated with sodium hypochlorite solutions with a plan depicted development and efficient discharge location.

Vehicles access: Specialised access for vehicles must be provided.

The two methods by which the effluent or the treated waste water separated out and can be treated are:  

  • Septic tank
  • Sewage treatment plants

Extension to the report:

Safety measures during disposal of domestic sewage water

The sewage treatment referred to the wastewater treatment. Sewage treatment is the process in which the contamination is being, removed from the wastewater. The various process involved in the treatment of the sewage are physical treatment, chemical treatment, biological treatment. These process are involved in order to reduce the contamination and produce safer treated wastewater.

The evaluation of different methods used to dispose sludge

Septic tank : A septic tank is a tank which is which is typically underground, in which the sewage is collected and are allowed to decompose through various bacterial activity before draining by various means of soakaways. Septic tank is the private sewage disposal plant which is commonly found in buildings and rural areas. The purpose of the septic tank is simple, as mentioned above septic tank is a large setting chamber. The various treatment of the effluent takes place in septic tank. The plumbing fixture is the structure is served by an septic system discharge liquid and semi solid waste to the septic tank. Septic tank produces effluent which is primarily treated and it has distinct foul odor. The effluent is very toxic for the aquatic life. Therefore the effluent  needs to be treated in safe manner in order to reduce the impact of its discharge. 

Sewage Treatment plant: In order to release the sewage water which is harmful to the life of the human health. Improvisation in the technologies which needs to be done in order to treat the toxic substances in order to remove such chemicals matters. Increasing the awareness about the impact of the environmental pollution and advancement of scientific knowledge results zero discharge for the pollution in the sewage system. Bio-solids which can be recycled and reused and it can be act as controlling measures. Some of the other alternative methods can be used such as landfills and composites for ensuring safety.

Task 4


Methods to dispose the domestic solid waste Hong Kong:

 Solid domestic waste is increasing day by day which is result of growing human population and consumption. Solid domestic waste are of two types disposable and non disposable. Disposable waste which can be easily disposable and it does not cause any harm to the environment. On the other hand non disposable waste which is not easily disposable and it causes several issues to the environment. The various methods which can be use to dispose solid domestic waste in Hong Kong from residential buildings are:

Refuse chutes: A refuse chute which is an inclined channel through which refuse which can be passed down from the opening of the each floor section. It is connected to the ground floor of the building.

Compaction: Compaction of the waste is the process of shrinking the waste by reducing in its size. It is the process in which the garbage compactors and waste collection vehicles collects the waste and compress it so that more of the waste can be store at the same place. Later the waste is compacted again in order to expand the landfill life span. The various ways of shrinking the refuse:

Refuse which is conveyed to the compaction system by a liver floor system.

Refuse is compacted into seal tight containers compactors in order to compact waste.

The third step in which the operator in the compactor hall at the lower floor closes the container door and washes the container before leaving (Guerrero,  Maas,& Hogland, 2013).

The fourth step in which the container is transferred out and then replaced by an empty one.

Composting: Composting is the process where recycling is performed by natural means. Composting biodegrades organic waste such as food waste, trimming of grass, leaves, paper , crop residue etc. All these biodegradable waste are turned into a organic fertilizer and used for several beneficial purpose. Composting is the natural biological process. It is process in which various microorganisms including bacteria fungi   break downinto simpler substances. The composting process is dependent on the conditions of the environment within the composting system for example temperature, oxygen, moisture etc. Natural recycling which occurs on a continuous basis in the natural environment. The organic matter is metabolized by the microorganisms and consumed by the invertebrates. The decomposed materials are used as the organic substances in order to support the growth of the plant's life.

Landfill: Landfill is the process in which the solid waste is been disposed by burying it. Landfill is the oldest form of waste treatment and the most common methods of organized disposable of waste; it was practice in many parts of the world. In the recent times there are several thousands of tones of garbage which are extracted from the business industries, which needs to be disposed properly so that it does not cause any harm to the environment. There are strategic land off namely (WENT) West New Territories (SENT) South East New Territories and (NENT) North East New Territories landfill which are considered as the key disposable sites for the Hong Kong. Landfill is considered as the best method in order to decompose the solid waste materials without causing any harm to the environment (Guerrero, Maas, & Hogland, 2013).

Features of landfill 

 Figure 3: Features of landfill

Treatment Process

Treatment process is where waste is being treated before disposing it. There are three types of Treatment process;

Pretreatment process: The first step is the pretreatment in which the food waste is delivered into the pilot plant and excessive water is drained out. Later the food waste left which are mixed with bulking agent in order to create moisture content composting process.

Composting: The second step is composting in which the mixed waste filled in composting drum units. The decomposition of waste within the drum creates biological bacteria. Heat is released during the time of the decomposition process. The temperature inside the drum is kept within 55 C to 70 C for the proper decomposition process.

Curing: Curing is the third step of decomposition in which the premature compost which is piled up on the curing pads in order to undergo a curing period of 30 days approx in order to ensure proper complete decomposition (Charlesworth, Faraj-Llyod, & Coupe, 2017).

Final product: After completing all the steps of decomposition, the final step in which the mature compost are sieved by vibrating the products. The vibration  which removes the bulking agents and contaminants before they are packed for delivery. The big chips which are extracted from the final products are reused used for composting process as a bulking agent (Garcia-Lodeiro, Carcelen-Taboada, Fernández-Jiménez & Palomo, 2016). 

 Composting Process

 Figure 4: Composting Process

Incineration: Incineration is the process that involves the combustion of the organic substance is contained in the waste materials. It is the process in which the waste is converted into ash, gas and heat. The incarnation process can reduce the volume of the waste by 90%. It is one of the modern technologies which are used by Municipal Corporation in order to treat municipal solid waste before disposal at landfills. In order to ensure gas emission  by the regulatory body for the public health and environment protection act modern designs and process are being made which controls the pollution and clean the gas (Deng, Chen, & Tam, 2015).

Incineration Process of waste

Figure 5: Incineration Process

Sorting: Sorting of waste is the process in which the waste is being separated into various different elements. The Sorting of waste, which can be done manually at the household and are collected through curbside collection schemes. It is a hand picking operation. The methods of sorting depend upon various factors such as the nature of waste. The various portion of waste such as glass, plastics, paper etc are separated. The separated materials, which are forward to the transfer, station for bulking up. This process involves manual picking lines in order to remove the erroneous materials and the use of the compacting machinery. If the waste is not sorted at the carbide, the municipal recycles must be taken to the centralized premises for sorting or processing. If the sorting is not done properly, it will cause lot of recycled product end up in landfills. Sorting at home is the first step towards recycling of the products. However, the people of the Hong Kong must practice Sorting of the waste material within the homes so that the waste can be easily disposable and recycle waste can be easily used.

 Sorting process of waste

Figure 5: Sorting process

Dealing the solid waste with methods of the disposal: 

After analyzing the recent survey it has been observed that more than half of the solid waste in Hong Kong is disposed in the following landfills and the sites where these waste are land filled will be completely filled by mid 2010s. In order to solve this problem the environmental protection department has placed high priority on promoting recycling of the products. However in recent years it has been observed that much of the waste is not being recycled, therefore in order to reduce the waste, government must plan various ways in order to recycle and decompose the waste generated from the Hong Kong residential buildings. The primary objective of teh government is to reduce the solid waste and promote recycling of the products. The various positive measures are taken by the government in order to dispose solid waste, such as developing eco-sustainable parks in which the land is provided for the establishment of industries  and environmentally products. The main objectives of this park are to build a future with less needless waste disposal (Christensen, Smith, Beasley & Powers 2014).


Disposal of Solid domestic waste and Organic waste 

The level of food waste generated from Hong Kong people is about 3,600 tons of food every day. Two third of this waste are generated from the household and one third  from commercial industries. As per the recent survey it has been observed that reducing the quantity of the food waste is critical for Hong Kong. On the other hand the waste generated from Yard is also known as the green waste. This types of waste decomposes in nature naturally. The government of Hong Kong was not focused on Yard waste until recently. They are working on overall waste to resource program for all types of waste.

Combustible and Noncombustible waste: which needs to be properly separated before decomposition. The combustible waste contains flammable or combustible liquids which creates fire hazards. These types of wastes must be kept in the following container. Combustible waste are cardboard, paper, cartons, cloths etc. However non combustible waste such as ashes, noncombustible rubbish, animals waste, radioactive material, equipment wires etc.

Legal requirements

 The waste management acts aims to promote better management of the solid waste. The waste act was formed in 1980. The main roles and goals of the act is to build comprehensive framework in order to manage waste. The ordinance has been amended several times in order to control chemical waste, illegal dumping of waste etc. Dealing with special kinds of wastes are also contained in other laws, for example oily waste which are generated from ships are controlled under the relevant legislation on merchant shipping.

Some of legislation act and their description are:

 Description   of Control
Waste disposal   ordinance 1980
Waste disposal regulations 1988
Waste disposal of chemical waste
Provides licenses for   collection of services and various disposal facilities of waste.
Sets out the various   legal requirement for proper handling of the livestock waste to guard against   danger to health of the public.
Requires payment of   changes for disposal of the chemical waste at the chemical waste treatment   centres.
Clinical waste   regulation 2010
Dumping at sea   ordinance  1995
 Provides for control and disposal and   delivery of the clinical waste.
Provides for control   on marine dumping and for various connected purposes.

Health and safety welfare 

Health and safety welfare, which is also, referred as the occupational health and safety OHS. The main purpose of OHS is to maintain the workplace health and safety welfare of people at work. Certain solid waste, are infectious which causes various hazardous effects to the human life. Therefore the waste which needs to be disposed properly that it does not cause any harm to the human life. Chemical waste generally comprises of the harmful substances which causes risk to health of the human being. However, on the other hand clinical waste is generated from various health care laboratories, which are very harmful for the environment and human life. Therefore, the waste needs to be decomposing properly (Li, Xue, Fang, & Poon, 2017).


 Damage to environment

 The waste which is generated from households and other industrial sector causes considerable damage to the environment.  During the time of disposal of the waste which results in emissions of atmospheric gases called greenhouse gas which affects the climate. During the time of decomposition of the organic waste in landfill which produces methane. The harmful methane gas is one of the main reasons for the greenhouse gas which causes significant damage to the environment and climate change. The waste is increasing due to population expansion and industrialization. Therefore various safety measures must be taken by the government in order to reduce the harmful waste are causing harm to the environment. 

Task 5


The stages of the processes that are used to purify and store drinking water

One of the biggest sources of water on the planet is rainfall. The hydrological cycle - the circular chain of events that involve simultaneous evaporation, condensation and precipitation - is the reason for rainfall. The global water cycle is characterized by nine major physical processes. These form a continuous water movement process. The pathway of rainfall begins from the passage of water that is stored in the atmosphere. This then goes through the major water bodies of the planet, such as oceans , glaciers and lakes. The water from the atmosphere rains down on the surface of earth and it passes through the soil and the underground rock layers. This process is very slow. All this water once again returns to the atmosphere through evaporation. The hydrological cycle has to no beginning or end. This is the fundamental characteristic of the cycle. Any of the following processes can help to make a proper study of the hydrological cycle:

Evaporation, condensation, precipitation, interception, infiltration, percolation, transpiration, run-off and storage. Some of the major processes are described below in a very simplified form. 

Evaporation: This process occurs when the physical form of water changes from a liquid state to a gaseous state. A considerable amount of heat is necessary for this to happen. Solar heat, air temperature, vapor pressure, solar radiation, atmospheric pressure rate are the normal causes for evaporation. Even human activities can cause evaporation. The moisture that is created due to evaporation rises to the atmosphere and then comes back down on the surface once again in the forms of rainfall or snowfall. There always exists some vapor in the atmosphere. 

Condensation: In this process, water vapor changes its physical form from gaseous state to another state, most commonly liquid. Water vapor condenses into fog, clouds or dew. Cooling of the atmosphere or increasing the amount of vapor in the air to its saturation point is the most common causes for water vapor to condense. 

Precipitation: This is the process where the condensed water vapor falls from the atmosphere to the grounds. Coalescence process and ice-crystal process are the two main factors for the clouds to release the precipitation. The water vapor condenses into liquid and reaches a critical size that allows gravity to make its presence felt. Rainfall and snowfall are the most common forms of precipitation.

The water that falls onto the ground gets dispersed again. It may fall on the water bodies, sip into the soil or get intercepted by plants. Then the whole process of evaporation starts once more, all over again. 

The primes sources of drinking water in the Hong Kong Islands are described below:

  • Rivers: The islands used to have water supply shortages up until the 1960s. Fresh water supply is still limited in Hong Kong. After the 60s, the Government of the country began to import raw water from the East River, Dongjiang, which flows in the neighboring province of Guangdong. Today, almost 80% of the country’s fresh water is supplied directly from Dongjiang. 
  • Small streams: These small streams or rivers do not flow throughout the year. But these make up for a large proportion of the country’s drinking water supply. Small streams can come to existence due to seasonal rainfall, small spring-fed ponds or depressions inside the surface. The health of these streams are very important for the entire river network of the area. These streams often merge into the bigger rivers of the province. However insignificant they may look, they do play a major role for the fresh water supplies of Hong Kong.
  • Shallow wells: These type of wells help to access the groundwater which are close to the surface of the planet. In this water supply system, the humans dig into the ground, where the soil is soft (most commonly sandy or clay), until they reach water layer. The hand pumps or mechanized pumps are used to get that water out of the ground and unto the surface for humans to use. 

  • Deep wells: These work based on the same principle as shallow wells. The only difference is the depth of the wells. The most important aspect of the depth is not the absolute depth of the well, but how much does the casting extend below the water level. A steel pipe serves as the lining of the well. It also protects the well from collapsing and also acts as protector of the well water from the surface water. Water level is also often found deeper into the ground than in shallow wells.


  • Bore holes: These holes are drilled into the ground, both soil and rock layers, using specialized equipments. The depth of a bore hole is dependant upon the quantity of the water that is necessary and the depth to the aquifer. A pump is used to bring the water out of the bore hole and unto the surface for usage. Water from boreholes is also stored and used for irrigation purposes. The bore hole has to be protected with a lid on top, so that the water does not get contaminated. A bore hole must be drilled in the ground at a place that is away from any pollution, where fertilizers and pesticides are applied on the surface. As the water that is collected from boreholes are mainly used for drinking and irrigation requirements, it is essential that the water is protected from any contamination.
  • Desalination of impounding reservoirs: An impounded reservoir is a storage system for the water that is collected from the river naturally. The volume of the water necessary dictates the size of the reservoir. The necessary amount of water is again governed by the volume of the water that is available through the inflow of the river. Reservoirs like these are mainly used to both to store drinking water as well as regulating the flow of the river during times of flood. 

Managing floods is another aspect as to why water must be stored in proper fashion. The management of flood often involves measures to lengthen time the the time for water to reach the river channel, thereby increasing the time of lag. 

There are two ways to manage floods:

  • Hard engineering options and
  • Soft engineering options

Hard engineering options are often more expensive than soft engineering options. They also have greater impacts on the river, which are more visible, as well as the surrounding landscape. Construction of dams, river engineering (deepening or widening of the river channel, straightening the river, altering the course of the river etc.) are the two most used hard engineering methods to manage floods. Soft engineering options include maintaining a proper vegetation population and density. 


Analyzing the techniques to purify drinking water in terms of efficiency and cost

There are two types of water: hard water and soft water. Soft water is the water that only has iron and sodium in it. Hard water is defined by the existence of more minerals in water. Rain water falls on the ground as soft water. Then while being dispersed into the ground, it gets mixed with calcium, chalk and magnesium and become shard water. Hard water is considered to be more suited as drinking water as it contains more minerals. If the hardness cannot be removed by boiling the water, it is referred to being permanently hard. pH level of  water decides the acidity or alkalinity of the water. If the pH level is below 7, then it is considered to be acidic, and if the level is over 7, then alkalinity is indicated. If the level is exactly 7, the water is considered to be neutral. 

Most waters do not have any taste or smell. Water should be exactly like this in order to be drinkable. But some waters have such foul stenches or color or both, that they are entirely unfit for being consumed at all. There are some properties of drinkable water. 

  • Color: Drinkable water must be colorless. Coagulation is used to reduce the color of drinking water. 
  • Turbidity: This is the measure of the amount of light that is trapped in the water because of the suspended matter in the water. It is very important to distinguish between turbidity and color. 
  • Taste and odor: Water may contain various tastes or odors. Many reasons can make water have taste or odor. But the fact that there are so many reasons for this, it is almost impossible to suggest one single universal solution to this problem. Every single problem has a different way to be dealt with. 

The already existing water gathering grounds (WGG) cover almost one third of the territory of Hong Kong. an average of 295 mcm/yr can be collected from these grounds. If the WGGs have to be extended of the country parks, they will have to face a lot of stringent rules to keep the water safe for drinking. But this is not considered to be best option to acquire drinking water as it would reduce the development potentials of the area. The limitations of water intake reduce the performances of the livestock in an almost dramatic manner. Water makes up for approximately 70 percent of the body weight of animals, consuming water is much more important than eating food. Domestic animals must be supplied fresh water regularly, else they would most certainly fail to work. High concentration of minerals often poses as a threat for animal health. 

Cultivating water

Water is the most important resource, of which there is no substitute. With the overuse of water, the threat of contaminating the water we use everyday has become one of the biggest problems of today’s world. New technologies are being invented only with the aim of obtaining fresh water and keeping the supply of drinking water constant. How the world uses its water will determine where the world would be going in the coming decades. Three aspects would govern how the future world would use its water: a) efficiency (maximizing the economic output, per unit of water collected), b) reuse (making water from a thrown away consumable product) and c) diversification of source (getting water from many resources as per lowest costs).

Using nitrates and landfills, rapid sand filters, micro-straining, slow sand filters, sterilization and chlorination are some of the ways that can be used to purify water. 


Justifying the methods to treat sewage and drinking water in financial, legal, environmental and safety terms:

Storage of the water that is to be supplied for drinking purposes is just as important as the methods of purifying the water. The prime reason for storing water is to make sure that during times of varying demands, water supply remains smooth - it acts as a buffer. 

The people of Hong Kong are provided with fresh drinking water by Her Majesty’s government. This government handles the legal and environmental issues that entail with storing of water.

Hong Kong government takes treatment of domestic sewage very seriously. A proper system is implemented to treat the sewage wastage by the government. Even if the situation goes out of hand, prompt actions are taken to bring the issues under control. Drilling water from the ground has become troublesome in recent times. Water is being mixed with harmful minerals underground as the water level is falling due to overuse. These health hazards are being looked into by the government with utmost importance and solutions are being adhered to. 


The study has mainly put its focus on the proper understanding of the underground drainage system and how can it be treated in the right ways. The fresh drinking water supply methods in Hong Kong Island have been studied. The study has made it clear that managing the sewage system is essential for the well being of the people living in the island. The environmental aspects of storing water and keeping the supply of drinkable water also have great impact on the people, as the study has successfully shown. The governing bodies that are given the responsibilities of dealing with the legal and environmental issues of supplying fresh water all are being dealt with by the government. The importance of understanding how to treat sewage is of utmost important if the water supply is to remain lag free in the future. The issues that may arise from storing water must be addressed immediately if the people and the livestocks are supposed to live in perfect health.