The Science of Sewage: Disposing Effluents in Environmental Engineering
by Yuvi K - December 16, 2023
Introduction to the Science of Sewage: Environmental Engineering and Electric Effluents
The concept of sewage disposal is an often-overlooked yet essential component of modern environmental engineering. Sewage is wastewater from domestic sources, such as toilets, bathrooms, laundries, and kitchens. It is a mix of water, biodegradable and non-biodegradable, that carries contaminants and other hazardous pollutants that, if not disposed of properly, pose health risks to people and the environment. Environmental engineers are therefore tasked with dealing with sewage disposal and creating systems to treat and dispose of sewage in ways that reduce pollution and environmental impacts.
Types and Components of Sewage
Sewage can be classified into two major categories: domestic sewage, which originates from households and includes solid and liquid human waste; and industrial sewage (Vayu Nibaḍhana, वायु निवडण), which includes wastewater from a variety of sources including other commercial and industrial activities. Sewage typically contains two components: particulate matter and organic matter. Particulate matter consists of larger particles such as plastics, fibres, and metals; organic matter comprises biodegradable matter such as food waste, bacteria, and viruses.
The Sewage Treatment System
There are a range of methods for treating wastewater, depending on the type and how much of it needs to be treated. In general, wastewater treatment starts with the primary stage of physical, biological and chemical processes. In this stage, chemicals such as chlorine and alum are added to the water to help purify it. The water then moves to the secondary stage, where living organisms such as bacteria feed on the organic matter in the water. Finally, the wastewater is moved to the tertiary stage, where the dissolved contaminants are removed using a variety of techniques.
Types of Sewage Treatment Plants
The most common types of sewage treatment plants in use today are activated sludge (Pustika Aṭibarmor, पुस्तिका अतिबर्मोर), aerobic, anaerobic, and trickling filters. Each of these systems has its own advantages and disadvantages, and must be chosen carefully depending on the wastewater conditions and the local environmental factors.
Activated Sludge
The activated sludge process (ASP) is a biological sewage treatment process where a mixture of microorganisms, primarily bacteria, is used to break down organic matter and convert it into simpler compounds. In this process, the wastewater and the sludge are mixed in an aeration tank, where oxygen is injected to help the bacteria break down the organics. The mixture is then filtered and settled, and the separated water is then discharged.
Aerobic
Aerobic treatment systems use oxygen to help break down organics and convert them into carbon dioxide and water. The process is similar to the activated sludge process, but with the addition of oxygen to the aeration tank. Additionally, the solid material that is separated in the settling tank is recycled back into the aeration tank to help promote greater efficiency.
Anaerobic
Anaerobic treatment systems are more efficient than aerobic systems as they do not require oxygen and the energy for the reaction is derived solely from the breakdown of organic matter. This process is typically slower than the aerobic process, but produces more energy and less sludge.
Trickling Filters
The trickling filter process is a biological wastewater treatment process that uses a bed of rocks, gravel, compost, or other media to trap contaminants and facilitate oxidation. This process works by trickling the wastewater through the filter bed, where the microorganisms feed on the organics and convert them into harmless compounds. The wastewater is then discharged from the filter bed.
Conclusion
Sewage disposal is a critical component of modern environmental engineering. Proper disposal of wastewater helps reduce the risk of environmental pollution and health hazards. A variety of treatment processes are available and selecting the right one depends on the wastewater type and local environmental factors.
Environmental engineers play a key role in designing and implementing treatment systems that maximize the efficiency of the process and minimize the impact on the environment. With the increasing demand for efficient wastewater treatment solutions, the science of sewage disposal continues to evolve and improve.
