Wastewater generated from various industrial sectors contains micropollutants, nutrients (nitrogen, sulfur, copper, phosphorus), carbon-based pollutants (antibiotics, aromatic hydrocarbons, biocides, phenolic compounds, and surfactants etc.) and heavy metals (cadmium, chromium, copper, mercury nickel, lead, and zinc) .
Treatment Process | Principle | Source of Pollutants | Removal Efficiency | Advantage | Disadvantage | Reference |
---|---|---|---|---|---|---|
Adsorption | Adsorption of specific contaminate on the surface of absorbent | Agricultural, industrial, and municipal wastewater with organic pollutants | 96% | Chemical less, eco-friendly, economical, better metal strap capability | Low selectivity, difficult maintenance, formation of waste products | [34][35] |
Adsorption, membrane-filtration, and photo-catalytic degradation (Hybrid) | Pollutant removal by serial treatment | Industrial wastewater with organic pollutants | 88–92% of COD; 85–91% of detergents & 91–98% of TS | More efficient, proved highly treated water | Difficult up-scaling | [36] |
Advance oxidation | Removal of contaminate through oxidation of reactive species | Industrial wastewater rich with organic and pesticidal contaminates | 53–96% of COD & 21–85% of TOC | Broad application, removal of odor molecules, efficient for removal of organic contaminants | High cost, incomplete removal of pollutants | [37] |
Biochar | Absorption contaminates for removal or degradation | Wastewater rich with dyes, heavy metals, organic inorganic pollutants, and phenolic compounds | 65–99% of dyes & >90% of phenols | Economical, large surface area, more pores, highly efficient | Low removal efficiency of raw biochar, less sustainable | [38] |
Biogenic Nanoparticles | Reduction or oxidation of metals by natural chemicals-based nanoparticles | Radio-active contamination, inorganic and organic pollutant | 75–99% of dyes & 66–85% of heavy metals | Sustainable, less toxic, inexpensive, less energy requirement | Instability, tricky recovery of intracellularly synthesized nanoparticles | [39][40] |
Biological method | Assimilation and dissimilation of pollutants | Nitrates, phosphates, dairy waste | >90% of COD & 38–90% of N2 | Economical, high biodegradability, efficient elimination of pollutants | Slow, requires constant maintenance, lower applicability, performance limited by operational conditions | [41][42] |
Microalgae | Uptake of pollutants as nutrients source for cell proliferation | Municipal and industrial wastewater rich with heavy metals, dyes, organic and inorganic pollutants | 20–98% of TP | Higher removal efficiency, non-toxic, less energy requirement, self-sustainable, produced biomass can be used for biofuel production | Performance limited due to operational conditions as well as type of wastewater, challenging biomass recovery, demands larger land | [43] |
Coagulation | Dissociation and hydrolysis | Heavy metals, textile, petroleum, cosmetics wastewater | >70% of COD & 90–100% of heavy metals | Ecofriendly, lower operational cost, efficient pollutant removal, energy efficient | Higher maintenance cost, difficult up-scaling, expensive | [44][45] |
Filtration | Separation via porous membrane | Industrial, municipal, and textile wastewater | 77% of COD; 99% of dyes & TC 74% of TN | Easy operation, cost-effective, and capable to remove suspended solid, alkalinity, inorganic and organic pollutants | Clogging of filter, limited removal of micro pollutant, higher cost of raw material | [31][46][47] |
Filtration and coagulant-flocculation (Hybrid) | Integration of filtration, coagulating and flocculant | Phenolic compounds, organic pollutants, suspended solids | 36% of COD; 81% fatty matter & 92% of TS | Highly efficient for removal of pollutants, lesser energy requirement | High maintenance cost | [48] |
Microbial electro-chemical Technology | Oxidation or reduction of pollutants by respiring microbes | Recalcitrant matter, industrial, domestic and food-processing wastewater | >25–63% of COD | Wide applicability, production of electricity, and other valuable commodities | Challenging up-scaling, high cost | [49] |
Nanomaterials | Play an action as absorbent for the photolytic degradation of contaminate | Inorganic and organic emerging pollutants, petrochemicals as well as heavy metals | 90–100% of heavy metals | Highly efficient with higher adsorption efficiency, friendly with other techniques | Less ecofriendly, expensive, toxic | [40][50] |