Physical Separation: Reuse Pollutants and Thermal Energy from Water
Abstract
:1. Introduction
2. Broken Carbon, Nitrogen, and Phosphorus Cycles
2.1. Broken Carbon Cycles
2.2. Broken Nitrogen Cycles
2.3. Broken Phosphorus Cycles
3. Conventional Sewage Treatment Based on Biological and Chemical Methods
4. Promising Sewage Treatment Based on Physical Separation
5. Conclusions
- (1)
- The conventional sewage treatment based on biological and chemical methods breaks the biogeochemical cycles (e.g., the carbon, nitrogen, and phosphorus cycles) and cannot remove hazardous materials including the viruses, microplastics, bacteria, and heavy metals. Accordingly, we should rethink the conceptual revolution of the principles of sewage treatment in 1890s [56], that is, “the replacement of a philosophy that saw sewage purification as the prevention of decomposition with one that tried to facilitate the biological processes that destroy sewage naturally”.
- (2)
- The carbon in the wastewater should be sent back to the soil rather than be used to produce carbon dioxide, methane, or carbonate. The nitrogen and phosphorus in the wastewater should be sent back to the soil or used for hydroponics rather than being mineralized. The thermal energy in the wastewater should be recovered and reused; whereas the chemical energy in the wastewater should be maintained rather than be recovered by producing methane and carbon dioxide. The hazardous materials should be removed.
- (3)
- The proposed promising sewage treatment system based on physical separation mainly consists of the source separators and the insoluble-pollutants separators, soluble-pollutants separators, and the wastewater heat recovery devices in the wastewater treatment plants;
- (4)
- The proposed promising sewage treatment system based on physical separation has the potential to replace conventional sewage treatment based on biological and chemical methods to fix the broken biogeochemical cycles (e.g., the carbon, nitrogen, and phosphorus cycles).
- (5)
- It is urgent to develop more advanced insoluble-pollutants separators and soluble-pollutants separators with high separation efficiency and low energy consumption [58,59,60], especially volume separators. Because the volume separators (e.g., functionalized sand filters) have the potential for replacing the surface separators (e.g., membranes).
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Nutrients and Thermal Energy | Flow of Matter and Energy | |
---|---|---|
Aerobic activated sludge process [38] | C | COD + O2→CO2 + H2O |
N | NH4+ + O2→NO3− + H+ + H2O NO3− + COD→N2↑ + CO2 + H2O | |
P | PO43− + Al3+→AlPO4↓ | |
Thermal energy | Waste | |
“Denitrifying phosphorus removal bacteria + Anaerobic treatments” [39] | C | COD→CH4 |
N, P | NH4+ + O2→NO3− + H+ + H2O NO3− + COD + PO43−→N2↑ + CO2 + H2O + Phosphate | |
Thermal energy | Waste | |
“Anaerobic treatment + Anammox process” [40] | C | COD→CH4 |
N | NH4+ + NO2−→N2↑ + 2H2O NH4+ +1.5O2→NO2− + 2H+ + H2O Together yield: 2NH4+ + 1.5O2→N2↑ + 2H+ + 3H2O | |
P | PO43− + Al3 + →AlPO4↓ | |
Thermal energy | Waste | |
“Anaerobic membrane bioreactor +Microbial electrochemical cells + Ion exchangers” [37] | C | COD→CH4 + Electricity |
N, P | N, P→Fertilizer | |
Thermal energy | Waste | |
“Microbial electrolytic carbon capture + Microalgae cultivation” [41] | C | COD + CO2→Carbonates |
N, P | N, P→Microalgae cultivation | |
Thermal energy | Waste |
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Tian, J.; Chen, X. Physical Separation: Reuse Pollutants and Thermal Energy from Water. Water 2023, 15, 1196. https://doi.org/10.3390/w15061196
Tian J, Chen X. Physical Separation: Reuse Pollutants and Thermal Energy from Water. Water. 2023; 15(6):1196. https://doi.org/10.3390/w15061196
Chicago/Turabian StyleTian, Jinyi, and Xiurong Chen. 2023. "Physical Separation: Reuse Pollutants and Thermal Energy from Water" Water 15, no. 6: 1196. https://doi.org/10.3390/w15061196
APA StyleTian, J., & Chen, X. (2023). Physical Separation: Reuse Pollutants and Thermal Energy from Water. Water, 15(6), 1196. https://doi.org/10.3390/w15061196