scholarly journals Synergistic Effect of Magnetite and Bioelectrochemical Systems on Anaerobic Digestion

2021 ◽  
Vol 8 (12) ◽  
pp. 198
Author(s):  
Nhlanganiso Ivan Madondo ◽  
Emmanuel Kweinor Tetteh ◽  
Sudesh Rathilal ◽  
Babatunde Femi Bakare
Keyword(s):  
Anaerobic Digestion ◽  
Synergistic Effect ◽  
Suspended Solids ◽  
Industrial Effluent ◽  
Oxygen Demand ◽  
Electrolysis Cell ◽  
Bioelectrochemical Systems ◽  
Methane Generation ◽  
Copper Electrodes ◽  
Great Possibility

Conventionally, the anaerobic digestion of industrial effluent to biogas constitutes less than 65% methane, which warrants its potential methanation to mitigate carbon dioxide and other anthropogenic gas emissions. The performance of the anaerobic digestion process can be enhanced by improving biochemical activities. The aim of this study was to examine the synergistic effect of the magnetite and bioelectrochemical systems (BES) on anaerobic digestion by comparing four digesters, namely a microbial fuel cell (MFC), microbial electrolysis cell (MEC), MEC with 1 g of magnetite nanoparticles (MECM), and a control digester with only sewage sludge (500 mL) and inoculum (300 mL). The MFC digester was equipped with zinc and copper electrodes including a 100 Ω resistor, whereas the MEC was supplied with 0.4 V on the electrodes. The MECM digester performed better as it improved microbial activity, increased the content of methane (by 43% compared to 41% of the control), and reduced contaminants (carbon oxygen demand, phosphates, colour, turbidity, total suspended solids, and total organic carbon) by more than 81.9%. Current density (jmax = 25.0 mA/m2) and electrical conductivity (275 µS/cm) were also high. The prospects of combining magnetite and bioelectrochemical systems seem very promising as they showed a great possibility for use in bioelectrochemical methane generation and wastewater treatment.

Alkali pre-treatment of Sorghum Moench for biogas production

2013 ◽  
Vol 67 (9) ◽  
Author(s):  
Karina Michalska ◽  
Stanisław Ledakowicz
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Total Phenolic ◽  
Methane Generation ◽  
Pre Treatment ◽  
Alkali Hydrolysis ◽  
Almost All

AbstractThis work studies the influence of the alkali pre-treatment of Sorghum Moench — a representative of energy crops used in biogas production. Solutions containing various concentrations of sodium hydroxide were used to achieve the highest degradation of lignocellulosic structures. The results obtained after chemical pre-treatment indicate that the use of NaOH leads to the removal of almost all lignin (over 99 % in the case of 5 mass % NaOH) from the biomass, which is a prerequisite for efficient anaerobic digestion. Several parameters, such as chemical oxygen demand, total organic carbon, total phenolic content, volatile fatty acids, and general nitrogen were determined in the hydrolysates thus obtained in order to define the most favourable conditions. The best results were obtained for the Sorghum treated with 5 mass % NaOH at 121°C for 30 min The hydrolysate thus achieved consisted of high total phenolic compounds concentration (ca. 4.7 g L−1) and chemical oxygen demand value (ca. 45 g L−1). Although single alkali hydrolysis causes total degradation of glucose, a combined chemical and enzymatic pre-treatment of Sorghum leads to the release of large amounts of this monosaccharide into the supernatant. This indicates that alkali pre-treatment does not lead to complete cellulose destruction. The high degradation of lignin structure in the first step of the pre-treatment rendered the remainder of the biomass available for enzymatic action. A comparison of the efficiency of biogas production from untreated Sorghum and Sorghum treated with the use of NaOH and enzymes shows that chemical hydrolysis improves the anaerobic digestion effectiveness and the combined pre-treatment could have great potential for methane generation.

Evaluation of bioelectrochemical systems for wastewater treatment and sludge digestion

2014 ◽  
Author(s):  
◽  
Shashikanth Gajaraj
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Membrane Fouling ◽  
Microbial Fuel Cells ◽  
Microbial Consortia ◽  
Electrolysis Cell ◽  
Bioelectrochemical Systems ◽  
Wastewater Remediation ◽  
Sludge Digestion ◽  
Removal Efficiencies

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Much attention has been drawn by bioelectrochemical systems (BES) in the past years for wastewater treatment, due to its potential for enhanced wastewater treatment and resource recovery with added advantages in terms of energy generation, environmental footprint, operating stability and economics. This dissertation focuses on the potential to improve treatment efficiency of different wastewater components when assisted by BES. Modified Ludzack-Ettinger (MLE) process and membrane bioreactor (MBR) process assisted by microbial fuel cells (MFC) showed improved the nitrate-nitrogen removal efficiencies by upto 31% and 20% respectively, and reduced sludge produced by 11% and 6% respectively over the control reactors. While the unique design of the cathode significantly reduced physical membrane fouling, all other bioreactor performance was unaffected. Microbial electrolysis cell (MEC) assisted Cr[VI] reduction was faster in 60 days as compared to 69 days with MFC assisted systems and 85 days with the control. The total Cr removal efficiencies in the control system and the MFC or MEC-assisted systems were 20%, 55%, and 65%, respectively, demonstrating the ability of BES in assisting wastewater remediation process. Finally, MECs incorporated into anaerobic digestion resulted in increased production of methane of 9.4 % or 8.5% with both glucose and activated sludge respectively as the substrate. The integration of MEC had no impact on acetoclastic methanogens involved in anaerobic digestion, but significantly increased the populations of hydrogenotrophic methanogens, especially Methanobacteriales. In conclusion, the integration of BES with conventional wastewater treatment and sludge digestion process enhanced the removal of organic matter, nitrate and toxic metals while supporting healthy microbial consortia.

scholarly journals Effluent Treatment Technologies and Cost Research

2019 ◽  
Vol 9 (1) ◽  
pp. 6752-6757
Keyword(s):  
Industrial Wastewater ◽  
Microbial Growth ◽  
Suspended Solids ◽  
Batch Reactor ◽  
Industrial Effluent ◽  
Oxygen Demand ◽  
Industrial Effluents ◽  
Effluent Treatment ◽  
Treatment Technologies ◽  
The Common

The Common Effluent Treatment Plants (CETP) minimizes the pollution from industrial effluents. This plant monitors the reduction of physical and biochemical parameters such as total suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), heavy metals etc. The Sequential Batch Reactor (SBR), a variation of the ASP, combines all the treatment steps and processes into a single basin. An improved SBR process is Attached Growth Batch Reactor (AGBR) technology that provisions for microbial growth on the settled media/bed to treat the industrial wastewater using enzymes. This technology, when used to treat polluted river water, achieved about 90% of reduction of wastewater parameters. Hence the same is envisioned for the treatment of industrial effluent. In all the above methods the sludge settlement occurs. It contains biodegradable carbon content which could be used as feed for Biogas Digesters to produce Methane. The present study aims at examining the benefits of combining AGBR and Biogas Digester to implement the 3Rs (Reduce, Recycle, Reuse) [1]

The role of pH in the organic material solubilization of domestic sludge in anaerobic digestion

2003 ◽  
Vol 48 (3) ◽  
pp. 143-150 ◽  
Author(s):  
C. Yangin Gomec ◽  
R.E. Speece
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Ph Control ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Soluble Chemical Oxygen Demand ◽  
Ph Controlled

The effect of pH on anaerobic solubilization of domestic primary sludge and activated sludge was investigated and compared. Anaerobic solubilization was carried out in continuously stirred anaerobic reactors at mesophilic temperature (35°C) and pH was fixed at 6.5 (pH-controlled). Many researches reported the serious effects of pH on the solubilization of organic materials. Thus, the aim of pH control in the reactors consisting of domestic primary and activated sludges, was the evaluation of retardation in hydrolysis/acidogenesis at low pH values. Since primary and activated sludges have different biodegradation characteristics, results were compared. Results indicated that the destruction of Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) were better in the pH-controlled reactors. In both sludges, acetic acid was the main Volatile Fatty Acid (VFA) produced. In the pH-controlled reactors, VSS reduction was found to be 72% in about 20 days in the anaerobic digestion of activated sludge, whereas for the same interval VSS reduction could only be achieved by 32% in primary sludge at 35°C. When primary sludge was used as substrate, the pH-uncontrolled and the pH-controlled reactors removed VSS with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). However, production of VFAs and SCOD was ceased after 5 days in the pH-controlled reactor whereas VFAs and SCOD production continued after 5 days in the pH-uncontrolled reactor, which indicated that hydrolysis and fermentation did not complete and continued longer. On the other hand; in either the pH-uncontrolled or the pH-controlled reactor of activated sludge, VSS was not removed with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). It was apparent that solubilization was occurring, however this solubilization was not observed as VFA production. When total methane production and total COD (CODtot) removal were estimated using VSS removal in both types of sludges, results indicated that pH control enhanced biogas productions as well as CODtot removals.

Re-engineering Domestic Septic Tanks into Biogas Tanks

2018 ◽  
Vol 2 (2) ◽  
pp. 54-62
Author(s):  
Mawufemo Modjinou
Keyword(s):  
Anaerobic Digestion ◽  
Environmental Protection Agency ◽  
Suspended Solids ◽  
Sea Water ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Domestic Sewage ◽  
Green Technology ◽  
Septic Tank ◽  
Septic Tanks

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas asenergy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST),encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand(COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies haveshown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time becauseit lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies andeven into open places such as “Lavender Hills” without any treatment or disinfection. These practices cause severe public healthand environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with lessmanagement, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated throughthree (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made upof baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass andsewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packingmaterials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model isalso packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produceeffluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standardsfor the discharge of domestic effluents.

Re-engineering Domestic Septic Tanks into Biogas Tanks

2018 ◽  
Vol 2 (2) ◽  
pp. 54-62
Author(s):  
M. Modjinou, L. Darkwah
Keyword(s):  
Anaerobic Digestion ◽  
Environmental Protection Agency ◽  
Suspended Solids ◽  
Sea Water ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Domestic Sewage ◽  
Green Technology ◽  
Septic Tank ◽  
Septic Tanks

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas asenergy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST),encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand(COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies haveshown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time becauseit lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies andeven into open places such as “Lavender Hills” without any treatment or disinfection. These practices cause severe public healthand environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with lessmanagement, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated throughthree (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made upof baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass andsewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packingmaterials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model isalso packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produceeffluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standardsfor the discharge of domestic effluents.

scholarly journals Improvement of Waste Dehydrated Sludge for Anaerobic Digestion through High-Temperature and High-Pressure Solubilization

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 88 ◽  
Author(s):  
Eui-Hwan Hong ◽  
Jun-Gyu Park ◽  
Beom Lee ◽  
Wei-Qi Shi ◽  
Hang-Bae Jun
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Oxygen Demand ◽  
Stable Operation ◽  
Thermal Hydrolysis ◽  
Methane Generation ◽  
Methane Potential ◽  
Higher Temperature ◽  
Soluble Chemical Oxygen Demand ◽  
Pre Treatment

Biochemical methane potential tests and lab-scale continuous experiments were conducted to improve the yield and energy efficiency of anaerobic digestion through thermal hydrolysis pre-treatment. Methane generation, yield, and solubilization efficiency were evaluated through lab-scale tests. The pre-treated samples presented 50% biodegradability at 140 °C and 61.5% biodegradability at 165 °C. The increase in biodegradability was insignificant at 165 °C or higher temperature, and it was confirmed that the optimum conditions were achieved at 165 °C and 20 min of solubilization. The lab-scale continuous experiments confirmed that polymers were decomposed into low-molecular-weight compounds due to thermal hydrolysis, and pH decreased. NH4HCO3 produced by thermal hydrolysis acted as an alkali to enable a more stable operation compared to that before thermal hydrolysis. Total chemical oxygen demand as chromium (TCODCr) and soluble chemical oxygen demand as chromium (SCODCr) indicated 35.4% and 23.1% removal efficiency in terms of organic matter removal, respectively. Methane yield was approximately 0.35 kg m−3 at 2.0–4.0 kg (m3 d)−1 and 0.26 kg m−3 at 5.0 kg (m3 d)−1. The solubilization rate of 40.9% by thermal hydrolysis was confirmed through the lab-scale tests to determine its full-scale applicability.

scholarly journals Performance of a Full-Scale Anaerobic Digestion on Bakery Wastewater Treatment : Effect of Modified Distribution System

2020 ◽  
Vol 11 (1) ◽  
pp. 12-18
Author(s):  
Hanny Vistanty ◽  
Rizal Awaludin Malik ◽  
Aris Mukimin
Keyword(s):  
Anaerobic Digestion ◽  
Distribution System ◽  
Suspended Solids ◽  
Loading Rate ◽  
Oxygen Demand ◽  
Degradation Process ◽  
Full Scale ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
External Circulation

The effectiveness of a full-scale anaerobic digestion pretreatment was evaluated and the effect of wastewater distribution system was determined on the performance of bakery wastewater (BW) treatment. The BW was fed to 3 series of anaerobic compartments as the main degradation process. The distribution system of first compartment was modified and circulated to enhance contact and efficiency. While the effluent of last compartment was partly returned to the first compartment as an external circulation and the other part was further processed in activated sludge under aerobic conditions. The overall system was able to remove chemical oxygen demand (COD), total suspended solids (TSS), and biochemical oxygen demand (BOD) up to 97.7%, 99.7%, and 99.6%, respectively, at maximum organic loading rate of 6.3 kg COD/m3day. High removal of pollutants indicated that modified distribution of circulation is advantageous to the BW treatment

An efficient method to improve the production of methane from anaerobic digestion of waste activated sludge

2017 ◽  
Vol 76 (8) ◽  
pp. 2075-2084 ◽  
Author(s):  
Xiaolan Li ◽  
Xueqin Xu ◽  
Shansong Huang ◽  
Yun Zhou ◽  
Haijiang Jia
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Methane Production ◽  
Suspended Solids ◽  
Short Chain Fatty Acids ◽  
Hydrolysis Rate ◽  
Waste Activated Sludge ◽  
Organic Substrates ◽  
Methane Generation ◽  
Ozone Pretreatment

Methane production from waste activated sludge (WAS) anaerobic digestion is always low due to slow hydrolysis rate and inappropriate ratio of carbon to nitrogen (C/N). In this work, a novel approach, i.e., co-digestion of WAS and tobacco waste (TW) using ozone pretreatment, to greatly enhance the production of methane is reported. Experimental results showed the optimal C/N and ozone dosage for methane production was 24:1 and 90 mg/g suspended solids, and the corresponding methane production was 203.6 mL/g volatile suspended solids, which was 1.3-fold that in mono-WAS digestion. Further investigation showed the co-digestion of WAS and TW was beneficial to the consumptions of protein and cellulose; also, the presence of ozone enhanced the disruption of organic substrates and production of short chain fatty acids, which provided sufficient digestion substrates for methane generation. Analysis of microbial community structure suggested that members of the phyla Bacteroidetes and Firmicutes were the dominant species when ozone pretreatment was applied. The findings obtained in this work might be of great importance for the treatment of WAS and TW.

Sign in / Sign up

Export Citation Format

Share Document