scholarly journals Degradation of Plastics under Anaerobic Conditions: A Short Review

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 109 ◽  
Author(s):  
Xochitl Quecholac-Piña ◽  
María del Consuelo Hernández-Berriel ◽  
María del Consuelo Mañón-Salas ◽  
Rosa María Espinosa-Valdemar ◽  
Alethia Vázquez-Morillas
Keyword(s):  
Anaerobic Digestion ◽  
Short Review ◽  
Anaerobic Conditions ◽  
Experimental Conditions ◽  
Biodegradation Process ◽  
Thermophilic Conditions ◽  
Global Concern ◽  
Useful Life ◽  
Life Options ◽  
Temperature Water

Plastic waste is an issue of global concern because of the environmental impact of its accumulation in waste management systems and ecosystems. Biodegradability was proposed as a solution to overcome this problem; however, most biodegradable plastics were designed to degrade under aerobic conditions, ideally fulfilled in a composting plant. These new plastics could arrive to anaerobic environments, purposely or frequently, because of their mismanagement at the end of their useful life. This review analyzes the behavior of biodegradable and conventional plastics under anaerobic conditions, specifically in anaerobic digestion systems and landfills. A review was performed in order to identify: (a) the environmental conditions found in anaerobic digestion processes and landfills, as well as the mechanisms for degradation in those environments; (b) the experimental methods used for the assessment of biodegradation in anaerobic conditions; and (c) the extent of the biodegradation process for different plastics. Results show a remarkable variability of the biodegradation rate depending on the type of plastic and experimental conditions, with clearly better performance in anaerobic digestion systems, where temperature, water content, and inoculum are strictly controlled. The majority of the studied plastics showed that thermophilic conditions increase degradation. It should not be assumed that plastics designed to be degraded aerobically will biodegrade under anaerobic conditions, and an exact match must be done between the specific plastics and the end of life options that they will face.

Reductive Activation of Carbon Tetrachloride by Human Haemoglobin

1993 ◽  
Vol 21 (1) ◽  
pp. 57-64
Author(s):  
Roberta Ferrara ◽  
Michela Rezzadore ◽  
Stefano Cazzaro ◽  
Roberto Tolando ◽  
Maurizio Manno
Keyword(s):  
Carbon Monoxide ◽  
Carbon Tetrachloride ◽  
Anaerobic Incubation ◽  
Reductive Activation ◽  
Anaerobic Conditions ◽  
Prosthetic Group ◽  
Experimental Conditions ◽  
Human Haemoglobin ◽  
Reductive Metabolism

The reductive metabolism of carbon tetrachloride (CC14) by human haemoglobin (Hb) was observed in vitro by absolute absorption spectra recorded under anaerobic conditions. The following results were obtained: 1) a decrease of the 430nm peak typical of free reduced Hb (Hb2+); 2) the formation of a shoulder of absorbance, attributable to the production of a complex between Hb2+ and a metabolite of CC14 carbon monoxide (Hb-CO); and 3) the oxidation of some Hb2+ to methaemoglobin (Hb3+). The concentration of these three forms — Hb2+, Hb-CO and Hb3+ — during anaerobic incubation of Hb with CC14 was calculated algebraically from the absolute spectra. CO production was then calculated from the concentration of Hb-CO, using a suitable calibration curve. Interestingly, under identical experimental conditions, a substrate-dependent loss of Hb-derived haem, but not of Hb itself nor of haem-derived porphyrin fluorescence, was measured. Preliminary HPLC studies to clarify the discrepancy and, in particular, the role and fate of the haem group, showed two substrate-dependent modified haem products. The results indicate that human Hb is able to catalyse the reductive activation of CCl4, and suggest that, during the process, its prosthetic group haem may be modified by CC14 metabolites to products which maintain a tetrapyrrolic structure but are unable to react with pyridine.

Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process

2003 ◽  
Vol 48 (6) ◽  
pp. 255-262 ◽  
Author(s):  
E. Houbron ◽  
A. Larrinaga ◽  
E. Rustrian
Keyword(s):  
Anaerobic Digestion ◽  
Wash Water ◽  
Organic Loading Rate ◽  
Two Phase ◽  
Experimental Conditions ◽  
Coffee Pulp ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Working Volume ◽  
Acidogenic Reactor

This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with a working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g.l-1.d-1 and 0.5 COD g.l-1.d-1. The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g.l-1 respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD.l-1.d-1 and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD.l-1, and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH4 and 20% CO2. These results show that a humid coffee ‘Beneficio’ processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH4 m3.d-1. This represents an increase in methane production by a factor 3 to 5 compared to a ‘Beneficio’ using anaerobic digestion only for the treatment of its wastewater.

scholarly journals Removal of Orange G Dye from Aqueous Solution by Adsorption: A Short Review

2020 ◽  
Vol 9 (1) ◽  
pp. 318-327
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Low Cost ◽  
Short Review ◽  
Industrial Wastes ◽  
Present Review ◽  
Wastewater Remediation ◽  
Experimental Conditions ◽  
Adsorption Capacities ◽  
Orange G

Adsorption is a widely used technique for wastewater remediation. The process is effective and economical for the removal of various pollutants from wastewater, including dyes. Moreover, Besides commercial activated carbon, different low-cost materials such as agricultural and industrial wastes are now used as adsorbents. The present review focused on the removal of a teratogenic and carcinogenic dye, orange G (OG) via adsorption using several adsorbents, together with the experimental conditions and their adsorption capacities. Based on the information compiled, various adsorbents have shown promising potential for OG removal.

Biodegradation of PAH and DEHP micro-pollutants in mesophilic and thermophilic anaerobic sewage sludge digestion

2006 ◽  
Vol 53 (8) ◽  
pp. 99-107 ◽  
Author(s):  
T. Benabdallah El-Hadj ◽  
J. Dosta ◽  
J. Mata-Álvarez
Keyword(s):  
Anaerobic Digestion ◽  
Wastewater Treatment Plants ◽  
Economic Cost ◽  
Process Efficiency ◽  
Sludge Digestion ◽  
Thermophilic Conditions ◽  
Polycyclic Aromatic ◽  
Positive Effect ◽  
Process Product ◽  
Micro Pollutants

Anaerobic digestion for the treatment of sludge in wastewater treatment plants has been reported to produce a low organic loaded effluent with an acceptable economic cost. But in the last years, new regulations and the increasing sludge production invite us to find an alternative and/or to improve the process efficiency. Moreover, the use of the effluent as fertilizer in agriculture imposes more restrictions on digestion process product and its micropollutant contents to protect the environment. In this study, a performance of the anaerobic digestion under mesophilic and thermophilic conditions at different hydraulic retention times (HRT) is assessed and the removal efficiencies of two important compounds or family compounds (Polycyclic Aromatic Hydrocarbons, PAH, and Di-2-(Ethyl-Hexyl)-Phthalate, DEHP) are evaluated. A positive effect of thermophilic temperature was observed on both micropollutants' biodegradation. However, HRT effect also had an important role for DEHP and low molecular weighted PAH removal.

Application of ADM1 for the simulation of anaerobic digestion of olive pulp under mesophilic and thermophilic conditions

2006 ◽  
Vol 54 (4) ◽  
pp. 149-156 ◽  
Author(s):  
H. Kalfas ◽  
I.V. Skiadas ◽  
H.N. Gavala ◽  
K. Stamatelatou ◽  
G. Lyberatos
Keyword(s):  
Anaerobic Digestion ◽  
Olive Oil ◽  
Volatile Fatty Acids ◽  
Two Phase ◽  
Solids Concentration ◽  
Thermophilic Conditions ◽  
Maximum Uptake Rate ◽  
Standard Values ◽  
Olive Pulp ◽  
Phase Production

The management of the wastewater originating from olive oil producing industries poses a serious environmental problem. Recently, two-phase production of olive oil has been developed, leading to almost complete elimination of the bulk of the generated wastewater and, is thus regarded as an environmentally friendly technology. However, the main waste stream (olive pulp) is a slurry material characterized by high solids concentration (∼30%), requiring stabilisation before its final disposal. The anaerobic digestion of olive pulp is studied in this work under mesophilic and thermophilic conditions in CSTR-type digesters. The digesters were fed with water-diluted (1:4) olive pulp at an HRT of 20 days and an OLR of 3.94 kg COD m−3 d−1. In order to study the process kinetics, the digesters were subjected to impulse disturbances of different substrates. The IWA anaerobic digestion model was used to simulate the reactors' response. Some key process parameters, such as the specific maximum uptake rate constants and the saturation constants for the volatile fatty acids degradation were estimated and compared with the standard values suggested by the ADM1.

Anaerobic digestion of solid animal waste in an accumulation system at mesophilic and thermophilic conditions, start up

2003 ◽  
Vol 48 (4) ◽  
pp. 217-220 ◽  
Author(s):  
H.M. El-mashad ◽  
G. Zeeman ◽  
W.K.P. van Loon ◽  
G.P.A. Bot ◽  
G. Lettinga
Keyword(s):  
Anaerobic Digestion ◽  
Minor Effect ◽  
Mixing Conditions ◽  
Rate Limiting Step ◽  
Start Up ◽  
Accumulation System ◽  
Filling Time ◽  
Thermophilic Conditions ◽  
A Minor ◽  
Rate Limiting

The anaerobic digestion of solid animal wastes has been studied in an accumulation system (AC) at a filling time of 60 days followed by about 50 days batch digestion at 40 and 50°C. Poor mixing conditions during anaerobic digestion of solid wastes promote stratification of the substrate and intermediate products along the reactor height. The effect of layers stratification has also been followed in the AC system. The results showed a pronounced stratification of both CODdis and VFA concentrations along the AC system height. The temperature had a minor effect on the methane yield. The results also showed that methanogenesis was rate limiting in the AC system while the hydrolysis was the rate-limiting step during batch digestion.

Presence and fate of micropollutants during anaerobic digestion of sewage and their implications for the circular economy: A short review

2021 ◽  
Vol 9 (1) ◽  
pp. 104931
Author(s):  
María Venegas ◽  
Ana María Leiva ◽  
Carolina Reyes-Contreras ◽  
Patricio Neumann ◽  
Benjamín Piña ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Circular Economy ◽  
Short Review

scholarly journals Anaerobic Digestion Technology for Methane Production Using Deer Manure Under Different Experimental Conditions

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1819 ◽  
Author(s):  
Hanxi Wang ◽  
Jianling Xu ◽  
Lianxi Sheng ◽  
Xuejun Liu ◽  
Meihan Zong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Anaerobic Digestion ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Methane Production ◽  
Poultry Manure ◽  
Solid Content ◽  
Production Factor ◽  
Experimental Conditions ◽  
The Magnetic Field

Anaerobic digestion (AD) is an important technology for the treatment of livestock and poultry manure. The optimal experimental conditions were studied, with deer manure as a fermentation material and mushroom residue as an inoculum. At the same time, methane production was increased by adding zeolite and changing the magnetic field conditions. The results showed that a 6% solid content was the best condition for producing methane. The optimal conditions for methane production were obtained by adding 35 g of mushroom residue to 80 g of deer manure at 35 °C. The addition of organic wastewater (OW) improved methane production. The result of improving the methane production factor showed that adding zeolite during the reaction process could increase the methane production rate. When the amount of zeolite was over 8% total solids (TSes), methane production could improve, but the rate decreased. Setting a different magnetic field strength in the AD environment showed that when the distance between the magnetic field and the reactor was 50 mm and the magnetic field strength was 10–50 mT, the methane production increment and the content of methane in the mixed gases increased.

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