Integration of Microalgal Based Processes in Wastewater Treatment

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Wastewater Treatment and Reuse".

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 16884

Special Issue Editor


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Guest Editor
University of Milano - Bicocca, Department of Earth and Environmental Sciences, Milan, Italy
Interests: Applied ecology, with special concern on: Wastewater treatment and re-use (biological and chemical treatments, disinfection, removal of specific compounds); Water Pollution and management (pollution of rivers and lakes, management of water resources, ecological flow); Environmental Impact Assessment

Special Issue Information

Dear Colleagues,

The use of microalgae for wastewater treatment, also known as phycoremediation, has received growing interest in recent years, due to the potential low cost of the process and to the wide possibilities of resource recovery from microalgae from a circular economy perspective.

However, microalgae-based treatments are strongly dependent on the local climate and their overall performance depends on the activity of both microalgae and bacteria, always present in wastewater and in open systems. Another important point, which is increasingly emerging, is that on a full scale it is impossible to select the algal strain, and the properties of the produced biomass are strongly affected by the environmental and operating conditions, as well as by the chemical composition of the influent. Further, the composition of the microalgal population shows seasonal changes.

Among the different research topics, the Special Issue will include:

  • Evaluation of the specific contribution of microalgae and bacteria in wastewater treatment
  • Long-term experiences at full and pilot scale: removal efficiency of nutrients, metals and emerging and priority pollutants, disinfection.
  • Knowledge and management of limiting factors
  • Causes of sudden failures in microalgae cultures, including parasites and other biological interactions
  • Valorisation of the microalgal biomass (anaerobic digestion, bioethanol and biodiesel, biofertilizers, feed for animals and aquaculture, extraction of selected compounds).

Manuscripts should provide insights into feasibility, including economic and technical aspects for full-scale implementation.

Dr. Valeria Mezzanotte
Guest Editor

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Keywords

  • Wastewater
  • Microalgae/bacteria consortia
  • Process and design optimization
  • Limiting factors
  • Valorization of microalgal biomass

Published Papers (4 papers)

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Research

12 pages, 2436 KiB  
Article
Real-Time Behavior of a Microalgae–Bacteria Consortium Treating Wastewater in a Sequencing Batch Reactor in Response to Feeding Time and Agitation Mode
by Emna Mhedhbi, Nadia Khelifi, Paola Foladori and Issam Smaali
Water 2020, 12(7), 1893; https://doi.org/10.3390/w12071893 - 02 Jul 2020
Cited by 9 | Viewed by 2828
Abstract
A study of a microalgae–bacteria treatment system was conducted in a sequencing batch reactor (SBR) by combining a precultured native algae Nannochloropsis gaditana L2 with spontaneous municipal wastewater microorganisms. Two types of agitation, air mixing (AI) and mechanical mixing (MIX), were assessed at [...] Read more.
A study of a microalgae–bacteria treatment system was conducted in a sequencing batch reactor (SBR) by combining a precultured native algae Nannochloropsis gaditana L2 with spontaneous municipal wastewater microorganisms. Two types of agitation, air mixing (AI) and mechanical mixing (MIX), were assessed at continuous illumination (L) and photoperiod cycle light/dark (L/D). The obtained consortium, via native microalgae addition, has a better operational efficiency compared to spontaneous control. This allows the removal of 78% and 53% of total Kjeldhal nitrogen (TKN) and chemical oxygen demand (COD), respectively. Under the (L/D) photoperiod, the optimal removal rate (90% of TKN and 75% of COD) was obtained by the consortium at 4 days of hydraulic retention time (HRT) using the AI mode. Moreover, during feeding during dark (D/L) photoperiod, the highest removal rate (83% TKN and 82% COD) was recorded at 4 days HRT using the AI mode. These results bring, at the scale of a bioreactor, new data regarding the mode of aeration and the feeding time. They prove the concept of such a technology, increasing the attraction of microalgae-based wastewater treatment. Full article
(This article belongs to the Special Issue Integration of Microalgal Based Processes in Wastewater Treatment)
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13 pages, 3155 KiB  
Article
Interactions between Microalgae and Bacteria in the Treatment of Wastewater from Milk Whey Processing
by Francesca Marazzi, Micol Bellucci, Tania Fantasia, Elena Ficara and Valeria Mezzanotte
Water 2020, 12(1), 297; https://doi.org/10.3390/w12010297 - 19 Jan 2020
Cited by 39 | Viewed by 5570
Abstract
Milk whey processing wastewaters (MWPWs) are characterized by high COD and organic nitrogen content; the concentrations of phosphorus are also relevant. A microalgal-based process was tested at lab scale in order to assess the feasibility of treating MWPW without any dilution or pre-treatment. [...] Read more.
Milk whey processing wastewaters (MWPWs) are characterized by high COD and organic nitrogen content; the concentrations of phosphorus are also relevant. A microalgal-based process was tested at lab scale in order to assess the feasibility of treating MWPW without any dilution or pre-treatment. Different microalgal strains and populations were tested. Based on the obtained results, Scenedesmus acuminatus (SA) and a mixed population (PM) chiefly made of Chlorella, Scenedesmus, and Chlamydomonas spp. were grown in duplicate for 70 days in Plexiglas column photobioreactors (PBRs), fed continuously (2.5 L culture volume, 7 days hydraulic retention time). Nutrient removal, microalgae growth, photosynthetic efficiency, and the composition of microalgal populations in the columns were monitored. At steady state, the microalgal growth was similar for SA and PM. The average removal efficiencies for the main pollutants were: 93% (SA), 94% (PM) for COD; 88% (SA) and 90% (PM) for total N; and 69% (SA) and 73% (PM) for total P. The residual pollution levels in the effluent from the PBRs were low enough to allow their discharge into surface waters; such good results were achieved thanks to the synergy between the microalgae and bacteria in the CO2 and oxygen production/consumption and in the nitrogen mineralization. Full article
(This article belongs to the Special Issue Integration of Microalgal Based Processes in Wastewater Treatment)
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14 pages, 1645 KiB  
Article
A Feasibility Study of Wastewater Treatment Using Domestic Microalgae and Analysis of Biomass for Potential Applications
by Jeong-Mi Do, Seung-Woo Jo, Il-Sup Kim, Ho Na, Jae Hak Lee, Han Soon Kim and Ho-Sung Yoon
Water 2019, 11(11), 2294; https://doi.org/10.3390/w11112294 - 01 Nov 2019
Cited by 33 | Viewed by 4615
Abstract
Water scarcity and emerging demands for renewable energy have increased concerns about energy security and advanced wastewater treatment, and microalgae have emerged as promising candidates to solve these problems. This study assesses the feasibility of microalgal wastewater treatment, and the utilization of the [...] Read more.
Water scarcity and emerging demands for renewable energy have increased concerns about energy security and advanced wastewater treatment, and microalgae have emerged as promising candidates to solve these problems. This study assesses the feasibility of microalgal wastewater treatment, and the utilization of the resulting microalgal biomass, as a renewable energy source. We cultured four selected microalgal species in filtered wastewater collected from the municipal treatment facility in Daegu, Republic of Korea. We measured nutrient consumption, growth rate, and physicochemical properties during cultivation, then analyzed the biomass for biochemical composition, ultimate analysis, proximate analysis, and biodiesel and lubricant properties, to estimate its potential applications. Desmodesmus sp. KNUA024 emerged as the most promising strain, removing 99.10% of ammonia nitrogen, 91.31% of total nitrogen, and 95.67% of total phosphate. Its biomass had a calorific value of 19.5 MJ kg−1, similar to terrestrial plants. α-linolenic acid was the most abundant polyunsaturated fatty acid (PUFA; 54.83%). Due to its PUFA content, Desmodesmus sp. KNUA024 also had a high iodine value, indicating its potential for use as a bio-lubricant. Therefore, Desmodesmus sp. KNUA024 shows promise for wastewater treatment, energy, and industrial applications. Full article
(This article belongs to the Special Issue Integration of Microalgal Based Processes in Wastewater Treatment)
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11 pages, 2129 KiB  
Article
Design and Bench-Scale Hydrodynamic Testing of Thin-Layer Wavy Photobioreactors
by Monica Moroni, Simona Lorino, Agnese Cicci and Marco Bravi
Water 2019, 11(7), 1521; https://doi.org/10.3390/w11071521 - 23 Jul 2019
Cited by 8 | Viewed by 3427
Abstract
In a thin-volume photobioreactor where a concentrated suspension of microalgae is circulated throughout the established spatial irradiance gradient, microalgal cells experience a time-variable irradiance. Deploying this feature is the most convenient way of obtaining the so-called “flashing light” effect, improving biomass production in [...] Read more.
In a thin-volume photobioreactor where a concentrated suspension of microalgae is circulated throughout the established spatial irradiance gradient, microalgal cells experience a time-variable irradiance. Deploying this feature is the most convenient way of obtaining the so-called “flashing light” effect, improving biomass production in high irradiance. This work investigates the light flashing features of sloping wavy photobioreactors, a recently proposed type, by introducing and validating a computational fluid dynamics (CFD) model. Two characteristic flow zones (straight top-to-bottom stream and local recirculation stream), both effective toward light flashing, have been found and characterized: a recirculation-induced frequency of 3.7 Hz and straight flow-induced frequency of 5.6 Hz were estimated. If the channel slope is increased, the recirculation area becomes less stable while the recirculation frequency is nearly constant with flow rate. The validated CFD model is a mighty tool that could be reliably used to further increase the flashing frequency by optimizing the design, dimensions, installation, and operational parameters of the sloping wavy photobioreactor. Full article
(This article belongs to the Special Issue Integration of Microalgal Based Processes in Wastewater Treatment)
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