Sewage Management and Treatment

Sewage Management and Treatment

DOI: 10.4018/978-1-7998-2645-3.ch010
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Abstract

Accumulation of sewage is a global issue that occurs primarily due to the rising rate of population growth. Without proper treatment and management, uncontrolled sewage generation threatens human health, environment, and society. This chapter briefly introduces sewage management and regulations. The conventional method of sewage and sludge treatment consists of pre-treatment, primary, secondary, and tertiary treatments before the sewage is safe to be discharged. Several sewage treatment technologies are introduced, namely the septic tank, intermittent decanted extended aeration, activated sludge system, membrane sewage treatment system, and finally the anaerobic digester.
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Introduction

Status of Sewage Management in Sabah

Two centuries ago, there were only one billion humans roaming this Earth. Fast forward to today, there is an astounding number of 7.6 billion humans living on our planet. At the beginning of time, the human population grew at a slow rate, but a few centuries ago, we have seen that the growth rate has multiplied radically. In the last two centuries alone, the world population was triple of that the whole history of humanity. The world population changes at an exhilarating rate, and this has great impacts of humanity on the Earth's environment. Still, this also serves as hope for better future, as we have a larger team with advanced thinking who can play a part in contributing solutions to the betterment of global well-being (Roser & Ortiz-Ospina, 2018).

The rising rate of population growth often leads to an increasing amount of waste generation. This trend is happening globally, especially in developing countries, such as Malaysia. Developing countries tend to have higher birth to date ratio, as a result of (1) the high number of poverty, and (2) lack of education and family planning. This phenomenon can be seen more clearly in rural states like Sabah. In Sabah, the annual growth rate has been increasing steadily, at an average rate of 1.4% in the last five years. To date, there are approximately 3.90 million (Figure 1) of people residing in Sabah, making it the second most populated state in Malaysia after Selangor (Department of Statistics Malaysia, 2018).

How the populations are spread across the Earth has a substantial effect on the environment. Urbanization of cities like Kota Kinabalu, Sabah allows for better management of the sewage system. This is attributed to the fact that urban cities are packed from the mass of people from rural regions who are migrating to look for employment and opportunities. Denser population allows for the construction of a centralized system that can cater for better management of sewage disposal. Contrarily, it will be difficult to construct a centralized sewage management system for a scattered rural population when looking at the perspective of cost-effectiveness. Urbanization can lead to better resources and waste management; however, if the growth rate outstrips the development rate, environmental problems could arise such as high level of centralized pollution and pressures on resources like water, food, and energy from the ongoing growth.

Figure 1.

Population size and annual population growth rate, Sabah, 2014-2018

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Source: Department of Statistics Malaysia, 2018

In the case of tourist arrivals, Sabah received an average of 3.38 million domestic and international tourists annually during the period of 2013 – 2017. The tourist arrivals trend in this five years duration recorded a slight decline from 2013 to 2015 and subsequently increased to the year 2017 (Figure 2). The ratio of Sabah’s inhabitants to tourists is almost 1, and it is not impossible that the number of tourists will outnumber the locals. The trend of increasing tourist arrivals to our country is a good mean for our economic and social developments. However, tourism produces large amounts of wastewater and the management has become challenging. Construction of resorts, hotels, and recreational spots could lead to increased sewage generation, and eventually, sewage pollution. Many tourists attraction in Sabah is concentrated at areas surrounding sea, lakes, and rivers, which serves as important water sources to the locals. Wastewater generated from tourism activities has polluted these water bodies surrounding these attraction sites, which consequently harms the flora and fauna species and presents a threat to both human health and the environment.

Figure 2.

Tourist arrivals, Sabah, 2013-2017

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Source: Sabah Tourism Board Official, 2018

Kota Kinabalu is situated along the West Coast of Sabah with several surrounding islands such as Gaya Island, Sapi Island, and Mamutik Island. Some of these areas are inhabited with ‘floating residential/village’ or ‘kampung air’, which is one of the unique landmarks of Sabah and has been around for many years. The Kampung Air, Tanjung Aru in Kota Kinabalu is one of the biggest ‘floating residential/village’, with around 3,000 residents living in 240 houses. Other floating settlements also reside around Likas, Sembulan, and Pulau Gaya in Kota Kinabalu, and also in other coastal districts like Semporna, located at the South-East Coast of Sabah.

The settlements are built over water on stilts and are often associated with negative images of garbage pollution, criminality, and an eyesore to the main city. Despite being an eye-catching attraction to some tourists, this type of settlement has no proper sewerage system, apart from being the main source of garbage litters to the neighbouring beaches and hotels. Currently, there are no regulations enforced to prevent the residents from throwing away rubbish into the sea. The absence of sewerage treatment system also perforce the villagers to directly discard their sewage into the sea.

Improper management of sewage that is commonly observed in Sabah is a public concern that needs to be robustly tackled by the government and also the locals. Mismanagement of sewage may lead to sewage runoff that presents hazards to both human and the environment. Sewage contamination of the coastal environment leads to large numbers of transmissible illnesses connected to bathing in beaches and ingestion of seafood. These diseases include diarrhoea, hepatitis, typhoid, and cholera that are caused by pathogens. The disease-causing bacteria can survive for several days to several weeks, while viruses can persist in the marine water and seafood for several months. More severely, hepatitis can live in the sea for more than a year (GESAMP, 2001).

The composition of sewage may contain various types of chemicals and special waste such as medical wastes, nutrients, industrial wastes, and heavy metals, which present additional threats to human and the environment. Nutrient contents from sewage runoff posed as the main source of nutrients to marine life. This often leads to the growth of algae blooms, which consequently cause damage to the coral reefs, as they block the filter-fed corals, hampering their survivability. The toxins from algae bloom also inflict health risks to human exposure.

Succinctly, sewage pollution presents hazards which impose risks to both human health and the environment such as:

  • Risks to human health as a result of the increase in total pathogens such as bacteria and viruses, and also toxins secreted by the algae blooms.

  • Risks to tourism activities.

  • Risks to the coral reef, aquatic flora and fauna, and marine ecosystem.

This chapter discusses the sewage management in Sabah in terms of the laws, regulations, and policy responses on sewage issues. The sewage concerns mainly arise from the population and tourism problems which are discussed early in this chapter. Due to that, proper treatments are required to manage the sewage as many threats may occur from improper management and treatment. The current treatments and management are discussed on the public, private, and individual perspectives. Additionally, the technologies which are significant to the sewage treatment application are introduced in the last section.

Key Terms in this Chapter

Activated Sludge System: Treatment method which utilizes aerobic microbes to feed on organic contaminants in wastewater to produce a high-quality effluent.

Sewage Treatment Process: Process of eliminating the contaminants present in municipal sewage wastewater which includes the pre-treatment, primary, secondary, and tertiary treatment processes.

Individual Septic Tank: The simplest form of sewerage system which is commonly installed in individual houses or premises using the principle of biological treatment, and separation of solid and liquid that occurs due to the difference in sewage density.

Private Sewerage: Sewerage system that is not owned or operated by the local authority or a municipality, and is not connected to the public sewerage system.

Intermittently Decanted Extended Aeration (IDEA): System which is the fusion between the typical sequencing batch reactor (SBR) and extended aeration (EA) systems.

Sludge: Semi-solid substances and mostly organic suspended sewage solids that are produced as a by-product from the sewage treatment process.

Sewage Treatment System: Collective term which includes the collection, transportation, pumping, treatment and final discharge of sewage.

Membrane Bioreactor: A system that combines membrane separation process and activated sludge process.

Anaerobic Digester: A system that uses microorganisms to break down biodegradable substances into biomass and biogas under anaerobic condition.

Public Sewerage: Sewerage system that is regulated by the local authority to treat and process sewage wastewater mainly in the urban areas, which comprises of the collection, transportation, pumping, treatment and final disposal of sewage.

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