Aspects of environmental engineering

ASPECTS OF ENVIRONMENTAL ENGINEERING

The various aspects related to environmental engineering highlighted in Fig. 1 are discussed below:

Environmental chemistry

Environmental chemistry focuses on the presence and impact of chemicals in soil, surface water, and groundwater. Environmental chemists stüdy how chemicals, usually contaminants, move through the environment. This is referred to as chemical “fate and transport”. They also study the effects of these contaminants on ecosystems, animals, and human health.

Environmental chemists are involved in the following activities:

(i) Advise on the movement and outcome of contaminants in soil and groundwater.

(ii) Assessment of long-term risks to ecological and human health.

(iii) Applying for environmental permits to undertake corrective strategies.

(iv) Classifying contaminated soils as hazardous waste

(v) Managing hazardous waste disposal and supervising onsite remediation.

In addition to working in the field, they may also conduct laboratory work. For example, they may analyze chemical interactions or relationships using chromatography or spectroscopy techniques. They may also take measurements, interpret data, and use computers to model chemical fate and transport.

Wastewater Treatment

It is the process of removing contaminants from wastewater generated by residential, institutional, commercial and industrial establishments. It includes household waste liquid from toilets, baths, showers, kitchens, and sinks draining into sewers.

Physical, chemical, and biological processes are used to remove contaminants and produce treated wastewater (or treated effluent) that is safer for the environment. A by-product of waste water treatment is usually a semi-solid waste or slurry, called sludge. The sludge has to undergo further treatment before disposal.

The infrastructure used for wastewater treatment is called a wastewater treatment plant or a sewage treatment plant in the case of municipal wastewater (households and small industries). For most cities, the sewer system will also carry industrial effluent to the treatment plant.

If the sewer system is a combined sewer, then it will also carry urban runoff (stormwater) to the treatment plant. Sewage water is taken to treatment plants through piping and in a flow aided by gravity and pumps. .

The separation and draining of household waste into greywater and blackwater is becoming more common in the developed world. Treated greywater is used for watering plants or recycled for flushing toilets.

Drinking Water Treatment

Treatment for drinking water production involves the removal of contaminants from raw water. The water produced should be pure enough for human consumption without any short term or long-term risk of any adverse health effect. Substances that are removed during the treatment process include suspended solids, bacteria, algae and minerals such as iron and manganese.

Water Quality Assessment

Water quality is determined by assessing three classes of attributes: biological, chemical, and physical. There are standards of water quality set for each of these three classes of attributes. The national standards for drinking water are developed by government agencies.

The drinking water standards are categorized as primary and secondary standards. Primary standards regulate organic and inorganic chemicals, microbial pathogens, and radioactive elements that may affect the safety of drinking water. These standards set a limit, namely, the Maximum Contaminant Level (MCL) on the highest concentrations of certain chemicals allowed in the drinking water supplied by a public water system.

Secondary drinking water standards regulate chloride, color, copper, corrosivity, foaming agents, iron, manganese, odor, pH, sulfates, total dissolved solids, and zinc. The above constituents and parameters affect the qualities of drinking water like taste, odor, color, and appearance. The concentration limit of these contaminants is referred to as the Secondary Maximum Contaminant Level (SMCL).

State agencies are responsible for monitoring public water supplies. They enforce the primary and secondary drinking water standards set by the agencies of governments.

Environmental Regulations

Environmental law, also known as environmental and natural resources law, is a collective term describing the network of treaties, statutes, common and customary laws addressing the effects of human activity on the natural environment. The regulations impose directions on air quality, water quality, waste management, contaminant cleanup and chemical safety.

Chemical Risk Assessment

Chemical risk assessment refers to the identification of hazards, evaluation of their risks and establishing control measures to secure the health and safety of employees. It is a major element for managing health and safety under the Safety, Health and Welfare at Work Act, 2005.

Groundwater Pollution Control

It refers to the control of groundwater pollution (also called groundwater contamination) which occurs when pollutants are released to the ground and reach groundwater. It can also occur naturally due to the presence of a minor and unwanted constituent, contaminant or impurity in the groundwater. In the above case, it is referred to as contamination rather than pollution.

Hazardous Waste Management

It refers to the control and management of wastes that has substantial or potential threats to public health or the environment. Some characteristics of the hazardous wastes are corrosivity, ignitability, reactivity and toxicity.

Solidwaste Disposal

The disposal of solid waste refers to the process of disposing the wastes such that they no longer possess any harmful threats to the health of human beings and other living beings. Some of the common solid waste disposal methods are landfill, incineration and recycling.

Hydrology Ecosystems (Ecohydrology)

It is an interdisciplinary field studying the interactions between water and ecosystems. These interactions may take place within water bodies, such as rivers and lakes, or on land, in forests, deserts, and other terrestrial ecosystems. Areas of research in ecohydrology include transpiration (explained in next chapter) and plant water use, adaption of organisms to their water environment, influence of vegetation on stream flow and function, and feedbacks between ecological processes and the hydrological cycle (details presented in next chapter).