Life cycle assessment of high rate algal ponds for wastewater treatment and resource recovery

Arashiro, Larissa T.; Montero, Neus; Ferrer, Ivet; Acién, F.G.; Gómez-Serrano, Cintia; Garfí, Marianna

doi:10.1016/j.scitotenv.2017.12.051

Cited by 178 publications

(81 citation statements)

References 46 publications

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“…The carbon footprint in WWTPs can be mitigated by decreasing the energy consumption through on-site energy recovery and improving the efficiency of aeration [83][84][85][86][87][88]; • Life cycle assessment (LCA)-LCA constitutes a standardized procedure which is employed for examining the environmental aspects characterizing wastewater treatment plants. This approach was adopted in a few studies in order to investigate the energy-related issues, including the production of biogas as well as AD [89][90][91]; • Data envelopment analysis (DEA)-DEA is commonly used to evaluate the eco-efficiency, frequently when the available data is limited. The eco-efficiency of a treatment plant is determined by integrating such factors as energy consumption, economic cost, removal of pollutants as well as contribution to the global warming effect [24,[92][93][94][95]; • Plant-wide modeling-the performance of wastewater treatment plant can be predicted using simulation tools and analysis of the data pertaining to energy consumption as well as the influent and effluent quality.…”

Section: "Smart Control" In Wastewater Treatmentmentioning

confidence: 99%

Aeration Process in Bioreactors as the Main Energy Consumer in a Wastewater Treatment Plant. Review of Solutions and Methods of Process Optimization

et al. 2019

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Due to the key role of the biological decomposition process of organic compounds in wastewater treatment, a very important thing is appropriate aeration of activated sludge, because microorganisms have to be supplied with an appropriate amount of oxygen. Aeration is one of the most energy-consuming processes in the conventional activated sludge systems of wastewater treatment technology (may consume from 50% to 90% of electricity used by a plant), which makes it the most cost-generating process incurred by treatment plants. The paper presents the construction of aeration systems, their classification as well as parameters and factors that significantly affect the aeration process e.g., oxygen transfer efficiency, diffuser fouling, methods of dealing with diffuser fouling, diffuser selection. Additionally, there are briefly presented “smart control” systems in wastewater treatment and effect of application control strategy based on Supervisory Control and Data Acquisition system connected with the decrease in the energy consumption for aeration of bioreactors with activated sludge. It is noted that before the process is optimized, the system should be equipped with suitable metering devices. Only when relevant data is available, the improvements can be carried out. However, it’s important, that the operator should regularly maintain good condition and high efficiency of diffusers.

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Section: "Smart Control" In Wastewater Treatmentmentioning

confidence: 99%

Aeration Process in Bioreactors as the Main Energy Consumer in a Wastewater Treatment Plant. Review of Solutions and Methods of Process Optimization

et al. 2019

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“…The biomass grown in the ponds is then harvested to obtain a clarified effluent. Harvested biomass can be valorized as an organic fertilizer [ 1 ] or to produce bioenergy, with anaerobic digestion (AD) being the most straightforward technology for this purpose [ 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

Strategies to Optimize Microalgae Conversion to Biogas: Co-Digestion, Pretreatment and Hydraulic Retention Time

et al. 2018

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This study aims at optimizing the anaerobic digestion (AD) of biomass in microalgal-based wastewater treatment systems. It comprises the co-digestion of microalgae with primary sludge, the thermal pretreatment (75 °C for 10 h) of microalgae and the role of the hydraulic retention time (HRT) in anaerobic digesters. Initially, a batch test comparing different microalgae (untreated and pretreated) and primary sludge proportions showed how the co-digestion improved the AD kinetics. The highest methane yield was observed by adding 75% of primary sludge to pretreated microalgae (339 mL CH4/g VS). This condition was then investigated in mesophilic lab-scale reactors. The average methane yield was 0.46 L CH4/g VS, which represented a 2.9-fold increase compared to pretreated microalgae mono-digestion. Conversely, microalgae showed a low methane yield despite the thermal pretreatment (0.16 L CH4/g VS). Indeed, microscopic analysis confirmed the presence of microalgae species with resistant cell walls (i.e., Stigioclonium sp. and diatoms). In order to improve their anaerobic biodegradability, the HRT was increased from 20 to 30 days, which led to a 50% methane yield increase. Overall, microalgae AD was substantially improved by the co-digestion with primary sludge, even without pretreatment, and increasing the HRT enhanced the AD of microalgae with resistant cell walls.

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“…Economically, it has already been shown that the production of bioproducts from microalgae grown in wastewater is more profitable than the generation of biogas. 50 …”

Section: Resultsmentioning

confidence: 99%

Natural Pigments and Biogas Recovery from Microalgae Grown in Wastewater

Arashiro

Ferrer

Pániker

et al. 2020

ACS Sustainable Chem. Eng.

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This study assessed the recovery of natural pigments (phycobiliproteins) and bioenergy (biogas) from microalgae grown in wastewater. A consortium of microalgae, mainly composed by Nostoc , Phormidium , and Geitlerinema , known to have high phycobiliproteins content, was grown in photobioreactors. The growth medium was composed by secondary effluent from a high rate algal pond (HRAP) along with the anaerobic digestion centrate, which aimed to enhance the N/P ratio, given the lack of nutrients in the secondary effluent. Additionally, the centrate is still a challenging anaerobic digestion residue since the high nitrogen concentrations have to be removed before disposal. Removal efficiencies up to 52% of COD, 86% of NH 4 + -N, and 100% of phosphorus were observed. The biomass composition was monitored over the experimental period in order to ensure stable cyanobacterial dominance in the mixed culture. Phycocyanin and phycoerythrin were extracted from harvested biomass, achieving maximum concentrations of 20.1 and 8.1 mg/g dry weight, respectively. The residual biomass from phycobiliproteins extraction was then used to produce biogas, with final methane yields ranging from 159 to 199 mL CH 4 /g VS. According to the results, by combining the extraction of pigments and the production of biogas from residual biomass, we would not only obtain high-value compounds, but also more energy (around 5–10% higher), as compared to the single recovery of biogas. The proposed process poses an example of resource recovery from biomass grown in wastewater, moving toward a circular bioeconomy.

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Life cycle assessment of high rate algal ponds for wastewater treatment and resource recovery

Cited by 178 publications

References 46 publications

Aeration Process in Bioreactors as the Main Energy Consumer in a Wastewater Treatment Plant. Review of Solutions and Methods of Process Optimization

Aeration Process in Bioreactors as the Main Energy Consumer in a Wastewater Treatment Plant. Review of Solutions and Methods of Process Optimization

Strategies to Optimize Microalgae Conversion to Biogas: Co-Digestion, Pretreatment and Hydraulic Retention Time

Natural Pigments and Biogas Recovery from Microalgae Grown in Wastewater

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