Freshwater constitutes less than three percent of the water available on Earth. But it is not readily consumable. Much of the freshwater is in the form of ice in the polar region. The rest is not distributed uniformly. Disease-causing microbes such as bacteria, fungi, amoebas, and viruses thrive in water. Also, industrial effluents containing harmful chemicals get mixed in water bodies and contaminate them. The excessive use of pesticides, fertilizers, and oil drilling activities pollutes the groundwater too. Therefore, the water available to us is not safe, and we need to treat it before using it.
Also, we have the responsibility to conserve and keep our environment clean. So treating the wastewater from industrial processes before discharging it is also a must. Below we discuss the latest technologies available for water treatment.
Decentralized Water Recycling
Wastewater treatment at a large scale has been in practice for years now. In the centralized system, the cost of infrastructure and maintenance is high. It applies to large-scale industries and civic-body-sponsored programs in urban areas. Now the industry has come up with decentralized water treatment systems suitable for homes and small businesses. There are different approaches, including constructed wetlands, anaerobic digestion, terra preta sanitation, waste stabilization ponds, and media filters. These treatment systems are simple, cost-effective, and easy to maintain. There is no need to transfer the wastewater through pipes. It gives the user the autonomy to choose a suitable method.
Households can opt for treating the greywater and use it for non-drinking purposes. Small industries can use separate systems to treat greywater and brown water. By owning a treatment plant, they can also market the fertilizer obtained by treating the wastewater.
Induced Gas Floatation
The method involves separating the contaminants such as solid particles and oil present in industrial water systems think this will work with the help of gas bubbles. It has a wide range of applications in the petroleum and chemical industries. The first step is to send the wastewater to a float tank along with coagulants. The coagulant flocculates the suspended particles. Next, gas bubbles are introduced into the system with the help of an impeller or a sparger. The bubbles stick to the suspended particle and raise them. A frothy layer forms at the top of the tank, and a skimmer system removes it. Oil refineries use nitrogen gas to create bubbles as normal air can cause an explosion. The method does not require chemicals. The operation and maintenance cost is low when compared to traditional water treatment systems. It reduces the toxicity of effluent water. It is one of the recommended procedures to prevent groundwater pollution.
Microbial Capacitive Desalination
Here both desalination and organic waste removal take place simultaneously. The process uses a microbial fuel cell, and the microbial action generates an electric current. The system consists of three main zones. These are the anodic compartment, cathodic compartment, and ion exchange membrane.
The oxidation of organic wastes takes place in the anodic part. Reduction happens at the cathodic region, and the positive ions passing through the cation exchange membrane remove the salt.
The technique requires less energy, is cost-effective, and environment-friendly too. It is applicable for wastewater treatment, groundwater denitrification, seawater, and brackish water desalination.
Graphene-based Water Purification
Graphene is a mesh of carbon atoms and is capable of forming a thin layer. The principle used is to make minuscule pores in the atom-thick layer of graphene.
This sieve of graphene permeates water molecules but not salts and organic compounds. But, it is easier to manufacture graphene oxide membranes on a larger scale. Constricted graphene oxide membrane acts as an excellent filter and allows only water molecules to pass it. The graphene oxide filter system consists of the oxide membrane sandwiched with constrictive material such as epoxy resins. These prevent water molecules from getting trapped within the layers of graphene oxide. Trapped water molecules can enlarge the gap between the layers. The process consumes less energy than the reverse osmosis method as no external pressure is required.
Coastal areas across nations often face water scarcity. Desalination of seawater is an area of research for the water treatment industries.
The latest technology in the field harnesses the energy of waves. The system consists of wave energy converters. The force produced by these drives the reverse osmosis unit installed near the shore.
The main advantage is that the process does not require external electricity. And, the brine water fed to the sea is less saline. It implies that there is a lesser disturbance to the marine ecosystem. Also, the process requires minimal infrastructure and the maintenance cost is less. Researchers are looking for ways to avoid the use of fossil fuels and make the desalination process eco-friendly.
Today, water is among the most scarce natural resources. Living beings need it for their growth and wellbeing. Also, industries need water for various processes. But our careless actions, such as massive deforestation and the discharge of untreated water into aquifers, make water sources unfit. Apart from water pollution, we are also responsible for groundwater depletion. Thus the goal of water treatment is to reduce freshwater usage and make effluent water less toxic.