Project no.: 2021/332775
Programme name: Energy Programme in Romania
Project name: Wastewater nanotechnology with advanced electro-oxidation, thermal hydrolysis, microplastic removal
Project Promoter: Kema Tronic SRL
Total project duration: 13 months – from 30.06.2022 to 28.07.2023
Total eligible expenses: EUR 135 095
Total grant approved: EUR 82 767
Co-financing: EUR 52 329
- the Need
This project addresses the problems of sewage treatment with activated sludge process (ASP).
Many sewage treatment plants use ASP in their secondary treatment steps . Although ASP is effective in eliminating most organic contaminants, studies indicate that many chemicals remain in the wastewater after treatment. At the same time, ASP requires aeration, which uses a large amount of electricity, and generates excess sludge, which requires huge economic efforts to ensure its safe disposal. Wastewater is tretaed without recovering its valuable resources
- the Response
The aim of the project is the development of an innovative nanotechnology, at TRL6 level, in order to replace 50% of the biological wastewater treatment with the treatment based on advanced electro-oxidation (EAOP) and thermal hydrolysis of sludge combined with EAOP. EAOP is induced by ultrasonic, electrokinetical disintegration and the production of micro-nano-bubbles.
This technology adopts the concept of circular economy in wastewater management, by:
• Reducing resources used to treat wastewater and sludge;
• Recovery of wastewater resources
• Reduction of waste from biological treatment and producing no waste
• Capture, sequestration and storage of CO2 and N2 produced by the treatment plant, removal of plastic microparticles from water and air;
This technology would be a breakthrough, low-cost, chemical-free solution for treating low concentrations of complex, hard to treat and in some instances toxic organics in industrial and municipal wastewater. Its simple and modular design enables integration into existing treatment plants, without disruption to current processes. It uses no chemicals during operation and releases none at the end of the process. It destroys organic contaminants without sewage sludge generation.
Treated wastewater can be used in agriculture, thus ensuring direct nutrient recovery from wastewater.
The technology applies to new and existing wwtps, aiming to achieve:
- Reducing excess sludge production or no excess sludge (for new wwtps)
- Reducing energy consumption with more than 50%
- Recovery of the ww heat, ensuring heating / cooling of the wwtp buildings and sludge thermal hydrolysis, with 30% sludge reduction
- capture-sequestration-storage of CO2, N2, O2 and ozone,
-plastic microparticle removal
-Generator of air micro bubbles, with diameter <1 mm; the air microbubble generator is based on the Venturi effect and is mounted on the continuous recirculation pipe of the treated liquid, aspirating air that contains CO2 and N2, produced by the treatment plant, and O2 from the air
-Self priming pump
-electrokinetic disintegration plant, with high voltage discharge with high frequency pulses (EK), with production of pulsating electric and magnetic field and nanobubbles as cavitation effect,
-ultrasonic disintegration plant (US), with nanobubble production as an effect of cavitation.
These plants produce in the liquid through synergistic effects nanobubbles, non-thermal plasma, free radicals, supercritical state water, resulting in advanced oxidation of organic substances. Cavitation germs consist of activated sludge particles and plastic microparticles. By continuous recirculation of the liquid in the reactor, repeated treatment is obtained.
-Container, Control panel
The new process can be applied for wastewater treatment (with EAOP nanotechnology and biology) and
1.Wastewater treatment unit (with EAOP nanotechnology and biology)
The Venturi device sucks air from the wastewater treatment plant, generating micro bubbles, with variable controlled air/ water flow rate. The micro bubbles contain CO2, N2 , O2. Water goes through this device and the result is a fluid- microbubbles mixture
The mixture goes through the high voltage discharge installation, where electron beam is generated, cavitation takes place, ozone is produced, free radicals and nano bubbles (nanobubbles I) are generated, then through the ultrasonic installation , producing ultrasonic waves. Cavitation takes place, free radicals and nano bubbles (nanobubbles II) are generated
Cavitation induces formation, growth and violent collapse of nanobubbles in a liquid medium.The rapid collapse of cavitation bubbles is nearly adiabatic,rendering each individual bubble a microreactor, inside which temperatures of the order of 5000˚K and pressures of hundreds of atmospheres have been shown to exist. As a results, water vapor entrapped inside a bubble is dissociated into H and OH radicals, and with other species present, various other reactive species such as HO2, O and H2O2 may form.
The mixture of water + MNB + ozone is sent to the aeration basin, where the decomposition of organic substances and nitrification will take place, both through biological activity and Electrochemical Advanced Oxidation Process (EAOP). By returning the mixture , nanobubbles I&II receive additional energy from both installations , and partial implosion of nanobubbles take place , generating temperatures of 5000˚C and pressure waves of 400 bar and new nanobubbles (nanobubbles III), by hydraulic shock
Also the pressure waves and hydraulic shock produce the disintegration of suspensions and activated sludge, into nano particles, that become cavitation nuclei, amplifying the nanobubbles process production
The free radicals, ozone and the pyrolisis process (with non-thermal plasma) lead to destruction of organic substance , pesticides, hormones, pharmaceuticals , viruses, and plastic particles
Aeration efficiency is increased due to aeration with micro/nanobubbles, boosting the efficiency of the existing activated sludge process
The so-called Electrochemical Advanced Oxidation Processes (EAOPs), are based on the electrochemical generation of very powerful oxidizing agents such as the radical OH∙, being then able to destroy organic compounds up to their complete mineralization. Such a process has a set of advantages, the most relevant being that no added chemicals are needed, since the radicals required for degradation of the organic matter are generated right from the water molecule. Together with the destruction of pathogens and their DNA, EAOPs also degrade organic micropollutants such as pesticides, hormones and pharmaceuticals. The final products of EAOP are CO2, H2O and minerals
The process is continuous and is automatically controlled with O2 sensors and frequency converter for the pump.
Aeration with micro-nano-bubbles has 5 times higher efficiency than fine bubbles aeration , thus 5 times less air required and 5 times less electricity required for biological ww treatment
2.Combined sludge treatment reactor with thermal hydrolysis, including sludge thickening
and Unit for recovery and amplification of thermal energy from wastewater, with heat pumps
The combined reactor treats the sludge and sludge water.
Tank 1 (outer tank): Storage
From this tank the sludge is sent to thickening , at about 7-8% DS and pumped into Tank 2
Tank 2 (central tank): Thermal hydrolysis
The thickened sludge enters the thermal hydrolysis tank, where it is maintained at 70˚ C for 3 days. Sludge dissolves as a result of the process of hydrolysis of complex organic compounds, such as proteins, polysaccharides and lipids, which create mono- and oligomers. There is also a partial decomposition of dissolved organic compounds and the creation of simple compounds: CO2, CO, CH4 and CH3OH. The heat source for thermal hydrolysis is the thermal energy recovered from the treated wastewater, obtaining hot water at 72˚C (circular economy). Domestic wastewater has a temperature between 12 ° C to 20 ° C; even in winter the wastewater temperature rarely drops below 10 ° C. Treated domestic wastewater can thus be an excellent source of energy by coupling a heat pump.
Tank 3 (intermediate tank): Disintegration and EAOP
Thermally hydrolyzed sludge, in which the organic matter is dissolved, decomposed and partially removed, flows into Tank 3 (intermediate tank). Here the technologies described above, for wastewater are used.
By continuous recirculation of the sludge in the reactor, the repeated sludge treatment is obtained.
The technologies in our proposal are at different development stages:
1. Thermal disintegration technology with self-provided heat : stage TRL 6 ,
2. Ulltrasonic and electrokinetic disintegrations are in stage TRL 8.
3. The synergic effect of sonication +electrokinetic disintegration+MNB , studied within SONOELCHEMCEL project, project approved for funding under NEPTUNE Blue Growth Accelerator. The stage of development achieved is TRL 7 – system prototype demonstration in operational environment
4. The synergic effect of thermal, sonication and electrokinetic disintegration, MNB is early field trial (TRL 5)
The innovative character of the proposed process consists in:
• generation of EAOP processes in a way not used so far in water treatment , with the synergistic effect of the following advanced electro-oxidation processes:
- production of micro-bubbles with Venturi effect, simultaneously with the capture, sequestration and storage of CO2 and N2, produced by the treatment plant
- production of air nanobubbles, as a result of cavitation
- generation of air nanobubbles as a result of the action of hydraulic waves, resulting from cavitation
For the treatment of sludge (and sludge water), Nanotermo was supplemented with
- thermal hydrolysis, for the additional decomposition of the organic
- recovery and storage of heat from treated wastewater for use in the process of thermal hydrolysis
The effects of the innovative NANOTERMO technology are:
- reduction of energy consumption for aeration and sludge treatment by approx. 45%
- reduction of sludge production by 70% on the total wwtp
- reduction of CO2, CH4 and H2S pollution generated by the treatment plant
- decomposition with EAOP of 25% of NH4 from sludge water
- reduction by 25% of the electricity demand for denitrification
- creating the possibility of obtaining irrigation water enriched with CO2, N2, O2 and ozone, sterilized (without chlorine) and recirculating water, CO2 and N2.
- the possibility of wastewater treatment at temperatures below 10-12 ˚C (temperatures at which biological treatment, nitrification-denitrification is not possible)
- capture and elimination of microplastic particles from water and air
- creating conditions for ZERO carbon treatment plants