Municipal sewage, which includes wastewater from households, businesses, and institutions, is the main contributor to water pollution in urban areas. It contains a variety of contaminants, including organic matter, nutrients, pathogens, and toxic chemicals.

Nitrates and phosphates, commonly found in fertilizers and detergents, are the primary cause of eutrophication. These nutrients stimulate excessive growth of algae and aquatic plants, leading to oxygen depletion and disruption of the aquatic ecosystem.

Bioaccumulation refers to the gradual accumulation of toxic substances in organisms as they consume contaminated food or water. These substances can move up the food chain, reaching higher concentrations in predators and posing a risk to human health.

Bioremediation is a process that employs microorganisms, such as bacteria and fungi, to degrade and remove contaminants from water. These microorganisms utilize the contaminants as a food source, converting them into harmless substances.

Constructed wetlands utilize the natural ability of plants to absorb and break down pollutants. The plants take up contaminants through their roots and store them in their tissues, effectively removing them from the water.

Ozonation is an AOP that involves the injection of ozone (O3) into water. Ozone reacts with water molecules to form hydroxyl radicals (OH-), which are highly reactive and effective in breaking down organic pollutants.

MBRs combine biological treatment with membrane filtration. The membrane acts as a physical barrier, separating and removing suspended solids, bacteria, and other contaminants from the treated water.

Nanofiltration membranes have pores that are smaller than those of conventional membranes, allowing them to remove heavy metals and other contaminants more effectively. The nanomaterials used in these membranes provide enhanced selectivity and efficiency in removing specific pollutants.

Ion exchange resins contain charged functional groups that attract and exchange ions with the contaminants in water. This process effectively removes ions such as heavy metals, nitrates, and phosphates, resulting in purified water.

Electrocoagulation is an electrochemical process that involves the application of an electric current to water. The electric field generates metal ions, which destabilize and coagulate contaminants, making them easier to remove through sedimentation or filtration.

MD is a thermally driven membrane process that utilizes a temperature gradient to separate water vapor from contaminants. The low operating temperature and the absence of phase change make MD an energy-efficient technology for water treatment.

SODIS is a simple and cost-effective method for disinfecting water using sunlight. It involves exposing water to direct sunlight in transparent plastic bottles for a specific duration, which effectively kills microorganisms through the combined action of solar radiation and heat.

RO is a pressure-driven membrane process that utilizes a semipermeable membrane to separate contaminants from water. The membrane allows water molecules to pass through while rejecting larger molecules, ions, and other contaminants, resulting in purified water.

Biosorption is a process that combines adsorption and biological mechanisms to remove contaminants from water. It involves the use of biological materials, such as bacteria, algae, or fungi, to adsorb and accumulate contaminants from water. The contaminants are then metabolized or immobilized by the biological material.

Activated carbon adsorption is a physical process that utilizes activated carbon to remove contaminants from water. Activated carbon has a large surface area and a porous structure, which allows it to adsorb a wide range of contaminants, including organic compounds, heavy metals, and pesticides.