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The global water stress has caused wastewater treatment and the process of returning the effluent to the water cycle much essential. The expansion of wastewater treatment plants entails tackling problems and barriers and proposing novel solutions. A challenge for the wastewater treatment industry is the existence of old transmission pipes and the technologies used
Relevance and challenges of the wastewater treatment industry
Wastewater is any water that has been contaminated by consumption and can’t be used repeatedly. Wastewater includes the following classes:
Sanitary wastewater: Domestic wastewater, commercial wastewater, and public wastewater;
Domestic wastewater: Sewage from a washroom in houses, shops, and stores;
Industrial wastewater: Sewage produced by factories, workshops, and industrial complexes;
Agricultural wastewater: Sewage generated from agricultural activities;
Surface wastewater or flood: Water from melting snow and ice or rain
Industrial wastewaters are more pressing because of a higher rate of production and containing various pollutants. Thus, the process of treating industrial wastewater is more challenging.
Industrial wastewater is generated upon using water in industrial activities or from industrial sources and during different stages of manufacturing and unusually forms the most dangerous type of wastewater.
Nearly no industry endures without water, and the water consumed with the sludge generates effluent and must be properly treated and then disposed of.
Given the vast variety of chemicals used in industry and various manufacturing techniques, the quality of industrial wastewater contamination varies and depends on the relevant industry. For example, in metal industries, the manufacturing process or coating of metal parts produces a large volume of effluents contaminated with heavy metals such as copper, cadmium, silver, mercury, cream, or nickel. Such metals are among the most hazardous pollutants and their genetic or carcinogenic effects have been proven. Or in the dairy industry, a large volume of soluble fats enter the wastewater from different parts of the production line and must be separated and removed by appropriate methods
Wastewater treatment is the process of converting sewage into water that can be reused or released into the environment with no risk or threat
Clean and healthy water is one of the most basic resources for human life on Earth. A technique to achieve safe water is wastewater treatment. Sewage is among the valuable and essential sources of water supply today, while in the past, sewage was considered useless and wasteful for various reasons
The quality and quantity of industrial wastewater differ by factories, requiring various specific treatment techniques. Thus, contaminations and impurities are extremely important to identify
Impurities in industrial wastewater include organic and inorganic pollutants
Inorganic pollutants
Inorganic pollutants include a variety of mineral salts, alkalis, chlorine, ammonia, mineral acids, and more.
Organic pollutants
Organic pollutants include a variety of sugars, fats, oils, proteins, hydrocarbons, organic acids, and more.
Advanced technologies reduce and/or minimize the production of waste and by-products and help recover valuable products from waste, as the biggest problem of the present century.
Conventional and old water and wastewater treatment processes aren’t energy-efficient. Moreover, these techniques require various equipment and high initial investment and come with a huge cost of equipment repair and maintenance.
A challenge with conventional methods is the disposal and decomposition of sludge produced in the wastewater treatment process. Such problems appear in conventional methods, while new technologies of wastewater treatment are developed for energy recovery and production.
New methods are economically affordable and require less equipment, energy, and initial costs. Moreover, new methods don’t produce sludge or solid waste in the wastewater treatment process.
As reported by the Lux Research institute, about a quarter of startups work on topics such as monitoring, forecasting, and control through sensors and the Internet of Things. Similarly, companies are focusing on water treatment systems. The scope of actions of startups active in the water and wastewater sector is shown in Figure 1 (Lux Research Institut).
Others (1%), pump and valve (2%), liquid/liquid and liquid/solid separation (4%), corrosion control (4%), reusing noncommon resources (4%), leakage repair and substitution of conveyance pipes (5%), desalination (5%), disinfection (10%, recycling metal or organic materials (16%), organic and solid materials treatment (24%), control, analysis, and prediction (25%)
In water treatment technologies, the primary wastewater undergoes various physical, chemical, and biological pretreatment processes. Physico-chemical methods include filtration, coagulation, precipitation, flotation, adsorption, ion exchange, advanced oxidation, electrolysis, and chemical reduction.
Biological treatment systems efficiently eliminate toxic contaminants. These methods are rather inexpensive and are preferred to other strategies. Biological methods include biological adsorption, aerobic and anaerobic biodegradation, or a combination of processes using bacteria, yeast, plants, algae, fungi, and enzymes.
Wastewaters often are highly colored and contain high biological and chemical oxygen. They show high electrical conductivity and are chemically alkaline. Thus, various parameters affect the cost of adopting a wastewater treatment method.
Various factors should be considered when selecting a treatment method, including the type of pollutants to be treated, the chemical composition of the wastewater, the cost of chemicals needed, the operating cost, and the cost of collecting waste generated by the treatment process
Ozone and ozone generators
Among the various technologies available for water and wastewater treatment processes, ozone technology is the most appealing in various industries due to its higher disinfection capacity and other advantages over chlorine
Ozone (O3) is a molecule consisting of three oxygen atoms. It is a blue gas with a stinking smell that is used as a disinfectant in the process of water and wastewater treatment in various industries due to its strong oxidizing properties. Ozone is a stronger disinfectant than chlorine, chlorine dioxide, chloramines, and other disinfectants, and kills many bacteria, viruses, eggs, and parasitic cysts. It is used for many purposes depending on the type of industry and the composition of wastewater
Ozone helps to eliminate harmful substances, dyes, odors, and microorganisms directly without creating harmful by-products or residues. Chlorine fails to fully eliminate microbial contamination, causes water quality alterations, and comes with destructive environmental effects, making the ozone gas to be more attractive and practical
Plasma technology is known as the next generation of wastewater treatment technologies worldwide. Plasma technology shows more advantages over other technologies, so extensive research is made to industrialize this technology. The advantages of this technology in water treatment include affordability in industrial applications, improving the capacity of wastewater treatment plants, and being free of chemicals.
Sparks in water or industrial wastewater caused by collisions with soluble particles and water molecules enhance energy and consequently the local temperature in the environment. This phenomenon leads to plasma cavitation and the creation of nano and microbubbles inside the aqueous medium.
Bubbles decomposition increases the local temperature of the water or effluent and can kill bacteria and microorganisms in the water or effluent. On the other hand, these bubbles contain electrons and ions, which decompose to form strong and disinfectant radicals. The presence of UV light and the release of O and OH radicals begin the oxidation of water-soluble substances or wastewater. These radicals ultimately cause clots and sediment in the sewage, which can eventually be separated into solids
Organic pollutants account for a large portion of industrial wastewater due to the activity of the petrochemical and food industries in the country, so strategies to remove organic pollutants from industrial wastewater are highly demanded in the country
Carbon fiber aerogel is a pretty strong, non-toxic, naturally-occurred, and recyclable adsorbent. Carbon fiber aerogels absorb various organic pollutants from industrial wastewater. This material can be produced from various cellulosic materials such as linen or waste paper
Carbon fiber aerogel has a very high specific surface area and low density that can absorb different organic materials within 100 to 200 times its weight. It is among the powerful absorbers of oils and all kinds of organic pollutants
Ecowotrth carbon fiber aerogel
Polymeric membrane filtration includes ultrafiltration (UF), nanofiltration (NF), microfiltration (MF), and reverse osmosis (RO). These techniques are widely used in water and wastewater industries. In most cases, water and wastewater treatment plants are designed and constructed using membrane treatment systems into membrane wastewater treatment packages and RO reverse osmosis systems.
These processes are important in various industries such as water and industrial wastewater treatment plants (e.g., petrochemical wastewater treatment) due to their advantages such as reducing energy consumption, high-efficiency mass transfer, and ease of use.