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Browsing UB - Comunicações em actas de encontros científicos internacionais by Subject "Anaerobic digestion"
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- Anaerobic digestion of a fish processing industry sludgePublication . Carvalho, L.; Di Berardino, Santino; Duarte, E.Due to the fact that all fish processing plants operating in Portugal send their sludge from the wastewater treatment process to landfill, and because it is a costly management policy, the aim of this work was to assess the potential use of this substrate for the production of biogas through the anaerobic process technology. Anaerobic digestion has long proven to be an efficient way for the production of a renewable fuel – Biogas - that can be used as a source of energy to produce electricity and heat. This renewable energy resource can be used to reduce the plant processing costs, reducing also the industry carbon footprint. So, the produced sludge becomes a valuable sub-product of the wastewater treatment process instead of being considered a waste, with disposal costs associated. In this study we performed mesophilic (35 ± 1°C) batch assays during 51 days. The inoculum used was from an anaerobic digester operating in a municipal WWTP, also at mesophilic conditions. The anaerobic digestion of the fish sludge produced 700 m3 of CH4/ton SV, which is a really promising result.
- Anaerobic digestion process for biogas and biomolecules production: microflora identification and characterizationPublication . Eusebio, Ana; Chaves, S.; Tenreiro, R.; Almeida-Vara, Elsa; Morana, A.; Ionata, E.; La Cara, F.; Marques, Isabel PaulaThe anaerobic process was efficient in organic matter removal. During the process, an interesting compound as quercetin was produced inside of reactor. Phylogenetic analysis showed the presence of phylotypes affiliated with gamma-Proteobacteria, Choroflexi, and Bacteroidetes. Archaea were represented by phylotypes belonging to the genus Methanosarcina and Methanosaeta.
- Bioactive compounds through anaerobic digestion of heterotrophic microalgae residuesPublication . Morana, A.; Squillaci, G.; Santos, Carla A.; La Cara, F.; Marques, Isabel PaulaSeveral important biomolecules are available into anaerobically digested effluents that were obtained from the biodiesel production process using heterotrophically grown microalga Chlorella protothecoides. Defatted microalgae residues and crude glycerol may undergo anaerobic digestion, separately and in admixture, providing methane/hydrogen and a digestate exploitable for agriculture applications. Furthermore, industrial interesting bioactive compounds such as polyphenols provided with antioxidant activity can be obtained. Anaerobic process offers a promising chance and can be advantageously combined with algae lipid-extraction techniques in order to make it more sustainable.
- Biogas production from mediterranean crop silagesPublication . Carvalho, L.; Di Berardino, Santino; Duarte, E.Anaerobic digestion has proven to be an efficient way for the production of a renewable fuel. The aim of this work was to study the potential use of two crop silages, yellow lupine (Lupinus luteus L.) and oilseed radish (Raphanus sativus var. oleifera cv. Pegletta), for the production of biogas through the process of anaerobic digestion. The use of yellow lupine was due to its capacity for nitrogen fixation, reducing the fertilization needs for the succeeding crop cycle and reducing also the GHG emissions due to the fertilizer production and its field application. The utilization of the oilseed radish was due to its root exudates with nematicide effect, reducing the needs for soil disinfection, working as a biological weapon and also due to the effect on soil compaction of its large roots, working as a bio-driller. The yellow lupine gave rise to 400 m3 of CH4.t-1 VS and the oilseed radish silage produced approximately 300 m3 of CH4.t-1 VS, proving to be good anaerobic substrates. The inoculum used for the batch digesters was sludge from an anaerobic digester of a WWTP.
- Biogas: olive mill wastewater as complementary substrate of piggery effluentPublication . Neves, André; Ramalho, Luís; Eusebio, Ana; Marques, Isabel Paula; Roseiro, Luisa B.ABSTRACT: he anaerobic digestion of a peculiar piggery effluent (PE), with a high organic content (93 g/L), was carry out using olive mill wastewater (OMW) as complementary substrate. From the different tested conditions–[100% PE],[70% PE+ 30% OMW],[50% PE+ 50% OMW],[20% PE+ 80% OMW]–units containing only PE and the lowest proportion of OMW in the mixture (30% OMW), provided the highest biogas volume of about 780 mL (70% CH4). Comparatively, identical quantities of each substrate ([50% PE+ 50% OMW]) generates some gas (320 mL, 60% CH4), understood as the result of an adaptation process by the microbial consortium, while the [20% PE+ 80% OMW] condition provided even less gas volume (120 mL, 6% CH4), probably due to the antimicrobial capacity of the phenolic compounds in OMW, confirming the negative influence of using so high OMW proportion.
- Combined biologic removal of sulphate for tanning industrial wastewatersPublication . Di Berardino, SantinoA biologic pretreatment technology of mixed tanneries wastewater, suitable for sulphate-rich industrial wastewaters, has been studied, in order to eliminate chemical precipitation and improve removal efficiency of the relevant pollutants. It couples an anaerobic reactor with an aerobic sulphide oxidant (ASO) step, where H2S2 is partially oxidized to elemental sulphur, and includes a recirculation system. The proposed solution provided Methanogenic Archae (MA) and Sulphate Reducing Bacteria (SRB) coexistence and controlled inhibition by partial oxidation of hydrogen sulphide.. The removal effiency of the anaerobic reactor was quite dependent on temperature and hydaulic retention time (HRT). COD removal varied between 32-68 % and sulphate removal (20-60%), referred to the mixture of the industrial effluent diluted with 50% of recirculation, at an Organic Load (OL) ranging from 0.5 to 1.5 kg CODM³ d⁻¹ and HRT from 1 to 5 days. The entire biologic pretreatment (AHF+ASO) resulted much more efficient and COD removal increased to 64-82% being less dependent on temperature variations. This process removed also a significant part (85%) of Chromium (Cr⁺³), by sorption into the biologic sludge. This two step biologic pretreatment, ensured better removal of relevant parameters than conventional chemical precipitation, avoided addition of chemical products, minimized excess sludge production, and also removed hydrogen sukphide and sulphate, resulting in a favorable alternative solution. The effluent from this stage was submitted to a sequencing batch nitrification/denitrification step, to improve the removal of the relevenat parameters. The average removal efficiency of entire process was appreciable and better than the conventional solution: COD = 88%, Sulphate = 68% and Nitrogen (kjeldahl) = 92%, chromium (Cr⁺³=96%). However, the presence of non degradable organic compounds delivered in the effluent from syntetic tanning, were hard to remove completely and did not allow fulfilling the severe standards for wastewater discharge in water course in terms of COD, Nitrogen (kjeldahl) and color. This requires and additional polishing step
- Hybrid anaerobic reactor: Brewery wastewater and piggery effluent valorisationPublication . Neves, André; Roseiro, Luisa B.; Ramalho, Luís; Eusebio, Ana; Marques, Isabel PaulaABSTRACT: A hybrid anaerobic reactor (HAR) operated to digest brewery wastewater, complemented with piggery effluent (60% and 40% v/v, respectively), under three hydraulic retention times: HRT: 5.7, 3.0 and 1.0 d. Along the first phase, the biogas of 0.9 LL− 1d− 1 evolved to 1.2 LL− 1d− 1 with a methane content of 77–78%. The HRT reduction to 3 days promoted the production until 2.1 LL− 1d− 1, with methane proportions of 79.5%. The operation with an even lower HRT (1 d) allowed to obtain a higher biogas (2.9 LL− 1d− 1, 79.5% CH4). HAR was successfully applied to the mixture digestion, even with a HRT as low as 1 day. Phenolic compounds with antioxidant capacity in effluent adds value, besides the supply of biogas/methane.
- Olive mill wastewater conversion into a stream for agricultural application: anaerobic and electrochemical processesPublication . Sampaio, M. A.; La Cara, F.; Correia, J. P.; Marques, Isabel PaulaAnaerobic digestion and the electrochemical oxidation were used to valorise the effluent of the olive oil production (olive mill wastewater, OMW). Anaerobiosis was realized in an anerobic hybrid reactor, operating at a low hydraulic retention time of about 6 days and digesting the raw OMW, without any previous substrate altarations. Electrochemical process worked with a dimensionally stable anode (DSA), without adding further support electrolytes, at low potential values and at moderate dulution factor of the substrate.
- Pretreatments applied to microalgae residues to enhance anaerobic digestionPublication . Rodrigues, M. P.; Eusebio, Ana; Santos, Carla A.; Marques, Isabel PaulaABSTRACT: Biomass of microalga Chlorella protothecoides, grown under autotrophic and heterotrophic conditions and subjected to pretreatments, were energetically valorized through anaerobic digestion process according to the substrates: autotrophic algae (A), heterotrophic algae (H), heterotrophic algae extracted (HE), autoclave pretreated heterotrophic algae (HPA), enzyme pretreated heterotrophic algae (HPE), ultrasound pretreated heterotrophic algae (HPU), and inoculum (I). Despite the application of pretreatments, the highest methane production was obtained in the algae extracted digestion with 172 mL CH4, against 153, 126 and 142 mL obtained in HPA, HPE and HPU, respectively. The COD removal capacity was higher in the HPA sample while the TS and VS removal reached higher values in the autotrophic alga.
- Purple non-sulphur photosynthetic bacteria in brewery wastewater during anaerobic digestionPublication . Goginyan, V.; Eusebio, Ana; Neves, André; Harutyunyan, B.; Hovhannisyan, R.; Andreasyan, N.; Marques, Isabel PaulaABSTRACT: Anaerobic digestion of brewery wastewater (BWW), under batch and constant light conditions, provided 70 mL of biogas with 80% CH4 and a COD removal of 64%, corresponding to a yield of 372 m3 biogas/kg COD removed. Additionally, a reddish pigmentation has developed throughout the process due to the growth of purple nonsulphur bacteria (PNSB). Based on morphological, physiological and cultural properties two strains of PNSB belonging to the genus Rhodobacter were isolated. The comparison of the nucleotide sequences of the 16S rRNA genes of the strains with the international databases (NCBI GenBank) made it possible to establish their taxonomical status as Rhodobacter capsulatus and R. azotoformans species.