111 research outputs found
Environmental odour management by artificial neural network – A review
Unwanted odour emissions are considered air pollutants that may cause detrimental impacts to the environment as well as an indicator of unhealthy air to the affected individuals resulting in annoyance and health related issues. These pollutants are challenging to handle due to their invisibility to the naked eye and can only be felt by the human olfactory stimuli. A strategy to address this issue is by introducing an intelligent processing system to odour monitoring instrument such as artificial neural network to achieve a robust result. In this paper, a review on the application of artificial neural network for the management of environmental odours is presented. The principal factors in developing an optimum artificial neural network were identified as elements, structure and learning algorithms. The management of environmental odour has been distinguished into four aspects such as measurement, characterization, control and treatment and continuous monitoring. For each aspect, the performance of the neural network is critically evaluated emphasizing the strengths and weaknesses. This work aims to address the scarcity of information by addressing the gaps from existing studies in terms of the selection of the most suitable configuration, the benefits and consequences. Adopting this technique could provide a new avenue in the management of environmental odours through the use of a powerful mathematical computing tool for a more efficient and reliable outcome. Keywords: Electronic nose, Environmental pollution, Human health, Odour emission, Public concer
Efficient and Sustainable Treatment of Tannery Wastewater by a Sequential Electrocoagulation-UV Photolytic Process
Tannery wastewater contains large amounts of pollutants that, if directly
discharged into ecosystems, can generate an environmental hazard. The present
investigation has focused the attention to the remediation of wastewater
originated from tanned leather in Tunisia. The analysis revealed wastewater
with a high level of chemical oxygen demand (COD) of 7376 mgO2/L. The
performance in reduction of COD, via electrocoagulation (EC) or UV photolysis
or, finally, operating electrocoagulation and photolysis in sequence was
examined. The effect of voltage and reaction time on COD reduction, as well as
the phytotoxicity were determined. Treated effluents were analysed by UV
spectroscopy, extracting the organic components with solvents differing in
polarity. A sequential EC and UV treatment of the tannery wastewater has been
proven effective in the reduction of COD. These treatments combined afforded
94.1 % of COD reduction, whereas the single EC and UV treatments afforded
respectively 85.7 and 55.9 %. The final COD value of 428.7 mg/L was found
largely below the limit of 1000 mg/L for admission of wastewater in public
sewerage network. Germination tests of Hordeum Vulgare seeds indicated reduced
toxicity for the remediated water. Energy consumptions of 33.33 kWh/m3 and
314.28 kWh/m3 were determined for the EC process and for the same followed by
UV treatment. Both those technologies are yet available and ready for scale-up
Production of phycobiliproteins, bioplastics and lipids by the cyanobacteria Synechocystis sp. treating secondary effluent in a biorefinery approach
Cyanobacteria have been identified as promising organisms to reuse nutrients from waste effluents and produce valuable compounds such as lipids, polyhydroxyalkanoates (PHAs), and pigments. However, almost all studies on cyanobacterial biorefineries have been performed under lab scale and short cultivation periods. The present study evaluates the cultivation of the cyanobacterium Synechocystis sp. in a pilot scale 30 L semi-continuous photobioreactor fed with secondary effluent for a period of 120 days to produce phycobiliproteins, polyhydroxybutyrate (PHB) and lipids. To this end, the harvested biomass from the semi-continuous photobioreactor was transferred into 5 L vertical column batch photobioreactors to perform PHB and lipid accumulation under nutrient starvation. Three hydraulic retention times (HRT) (6, 8 and 10 days) were tested in the semi-continuous photobioreactor to evaluate its influence on biomass growth and microbial community. A maximum biomass concentration of 1.413 g L-1 and maximum productivity of 173 mg L-1 d-1 was reached under HRT of 8 days. Microscopy analysis revealed a shift from Synechocystis sp. to Leptolyngbya sp. and green algae when HRT of 6 days was used. Continuous, stable production of phycobiliproteins in the semi-continuous photobioreactor was obtained, reaching a maximum content of 7.4%dcw in the biomass. In the batch photobioreactors a PHB content of 4.8%dcw was reached under 7 days of nitrogen and phosphorus starvation, while a lipids content of 44.7%dcw was achieved under 30 days of nitrogen starvation. PHB and lipids production was strongly dependent on the amount of nutrients withdrawn from the grow phase. In the case of lipids, their production was stimulated when there was only phosphorus depletion. While Nitrogen and phosphorus limitation was needed to enhance the PHB production. In conclusion, this study demonstrates the feasibility of cultivating cyanobacteria in treated wastewater to produce bio-based valuable compounds within a circular bioeconomy approach.This research was funded by the Spanish Ministry of Science, Innovation and Universities (MCIU), the Research National Agency (AEI), and the European Regional Development Fund (FEDER) [AL4BIO, RTI2018-099495-B-C21]. Estel Rueda is grateful to the Spanish Ministry of Education, Culture and Sport (FPU18/04941), Marta Bellver is grateful to the Spanish Ministry of Science and Innovation (PRE2019-091552) and RubĂ©n DĂez-Montero is grateful to the Spanish Ministry of Industry and Economy (IJC2019-042069-I) for their research grants.Peer ReviewedPostprint (published version
- …