• Energy Research

Abstract Nanoparticles (NPs) of trace metals such as Co, Ni, Fe and Fe3O4 were implemented in this study to compare their effects on biogas and methane production from anaerobic digestion of livestock manure. The most effective concentrations of NPs additives were determined based on our previous studies, and were 1 mg/L Co NPs, 2 mg/L Ni NPs, 20 mg/L Fe NPs and 20 mg/L Fe3O4 NPs. These concentrations of NPs additives were further investigated and compared to each other in this study and were found to significantly (p

To plan and design biogas plants, several calculations should be carried out; this requires time and effort, with the possibility of making mistakes. The objective of this study was to develop a tool to assist designers in planning and designing biogas plants by providing a new mathematical model and software program to save time and effort. A mathematical model was developed to plan and design biogas plants and their concrete structures. Subsequently, an electronic spark map (decision tree) was developed, and the mathematical model was integrated into the electronic spark map. Afterwards, C# (C Sharp) programming language was used to develop a software program by integrating the electronic spark map and the mathematical model, and making the user interface. The developed software is able to plan and design biogas plants, specify the dimensions of the different tanks (raw slurry tank, liquid organic matter tank, digester tank, secondary digester tank, and residue storage tank), and compute the required amounts of construction materials (iron rods, cement, sand, and gravel) required to build the designed structures. Furthermore, it calculates the capital investment and the fixed, variable, and total costs of the construction. Data from seven biogas plants were used to carry out the model validation and to evaluate the software program. The differences between actual and calculated values were determined, and the standard deviations were calculated. The coefficients of variation range between 3% and 7%. Furthermore, the calculated accuracy of the software program is 98%.

Agricultural and agro-industrial wastes (e.g., potato peel waste) are causing severe environmental problems. The processes of pretreatment, saccharification, and fermentation are the major obstacles in bioethanol production from wastes and must be overcome by efficient novel techniques. The effect of exposing the fungi (yeast) Saccharomyces cerevisiae to laser source with the addition of graphitic carbon nitride nanosheets (g-C3N4) with different concentrations on bioethanol production was investigated through the implementation of a batch anaerobic system and using potato peel waste (PPW). Dichromate test was implemented as quantitative analysis for quantification of the bioethanol yield. The benefits of this test were the appearance of green color indicating the identification of ethanol (C2H5OH) by bare eye and the ease to calculate the bioethanol yield through UV-visible spectrophotometry. The control sample (0.0 ppm of g-C3N4) showed only a 4% yield of bioethanol; however, by adding 150 ppm to PPW medium, 22.61% of ethanol was produced. Besides, laser irradiations (blue and red) as influencing parameters were studied with and without the addition of g-C3N4 nanomaterials aiming to increase the bioethanol. It was determined that the laser irradiation can trigger the bioethanol production (in case of red: 13.13% and in case of blue: 16.14% yields, respectively) compared to the control sample (in absence of g-C3N4). However, by adding different concentrations of g-C3N4 nanomaterials from 5 to 150 ppm, the bioethanol yield was increased as follows: in case of red: 56.11% and, in case of blue: 56.77%, respectively. It was found that using fungi and exposing it to the blue laser diode source having a wavelength of 450 nm and a power of 250 mW for a duration of 30 min with the addition of 150 mg L-1 of g-C3N4 nanomaterials delivered the highest bioethanol yield from PPW.

Abstract The use of trace metals as additives to the biogas production process to increase the biogas yield has been identified as a very common approach. Such additives can biostimulate the methanogenic bacteria to increase the biogas and methane production from the anaerobic digestion (AD) of livestock manure. The environmental impact of using the trace elements as manure additives still not evaluated. The objective of this paper is to conduct a comparative environmental impact evaluation of manure treatment with different trace elements for biogas production. The trace metals under evaluation were in the form of the chlorides of nickel (Ni), cobalt (Co) and iron (Fe) which were used as additives to the anaerobic digestion of livestock manure. The results were shown in the form of the specific impacts on global warming and greenhouse gas (GHG) emissions mitigation of producing and utilizing biogas as a bioenergy source. The results of this investigation show that the use of 1 g/m3 cobalt chloride (CoCl2) causes the lowest greenhouse gas emissions among all other evaluated trace metals which were calculated on the basis of CO2-equivalent. An important observation is that the greenhouse gas emissions from the electricity generated using biogas produced without any additives, i.e. without trace metals, were the highest among all other variants/scenarios.

Recently, dry anaerobic co-digestion is one of the mechanisms which have been increasingly used to improve the reactor’s performance for treating livestock manure with agricultural crop residues. Due to carbohydrate, protein and lipid existing in agricultural wastes, biogas yield decreased with higher reactor volume when using wet anaerobic digestion. In this regard, the aim of this work was to achieve the production of biogas using the dry anaerobic technology through livestock manure co-digestion with agricultural waste (AW) such as potato peels, lettuce leaves and peas peels. The manure and AW were mixed at a ratio of 2:1 for 15 min before being introduced into the batch anaerobic system. The results indicated that the co-digestion of lettuce leaves and manure yielded the highest production of methane and biogas which were 6610.2 and 12756.7 ml, respectively, compared to the control (manure) that yielded 4689.9 ml and 11606.7 ml, respectively. Additionally, the results indicated that the co-digestion of lettuce leaves and manure yielded the highest specific production of methane and biogas which were 405.5 ml CH4 g−1 VS and 782.6 ml biogas g−1 VS, respectively, compared to the mono-digestion of manure (control) that yielded 328 ml CH4 g−1 VS and 633 ml biogas g−1 VS, respectively. Eventually, dry anaerobic co-digestion process is an effective approach to waste treatment.

Recently, laser radiation and nanomaterials have been utilized to improve biogas yield via anaerobic digestion of herd’s manure through biostimulating methanogenic bacteria. Yet, laser irradiation and nanomaterials as anaerobic bacteria stimulant could have environmental impacts that have not been assessed or known. The aim of the current research was to understand and evaluate variable laser doses in the presence of nickel nanoparticles (Ni NPs) and their environmental impacts during the production of biogas from treated manure. A life cycle assessment scheme was employed to achieve this aim. The used laser doses were 0.5 h, 1 h and 2 h and correlated to 1-h incandescent light exposure, where all treatments received 2 g/m3 Ni NPs. The outcomes were conferred in the pattern of specific influences for the biogas utilization and production as an energy source. The studied impacts were global warming, greenhouse gas emissions mitigation, acidification, eutrophication, ozone layer depletion, freshwater ecotoxicity and prospective human toxicity. Results revealed that laser irradiation with the addition of Ni NPs during the biostimulation of anaerobic digestion has the least environmental adverse effects when compared to the control group.

Abstract This literature review discusses several aspects of biodiesel production from microalgae. This paper elucidates the optimal bioenvironmental conditions for microalgae cultivation, process design of algal biodiesel production, physicochemical properties of lipids extracted from microalgae and the properties of the produced biodiesel fuel, and the transesterification process. On the other hand, this paper illustrates the designs of up-to-date full-scale and lab-scale photobioreactors (PBRs). Furthermore, this paper argues different bioengineering aspects of biodiesel production from microalgae. Eventually, the measurements, calculations, design parameters, Life Cycle Analysis (LCA) of the production process are discussed.

Biohydrogen has significant feasibility since biological processes are much less energy intensive compared with electrolysis and thermo-chemical processes. It is widely recognized that considerable amounts of hydrogen (H2) can be produced from renewable resources without using energy from fossil fuels. Biological processes and bacterial fermentation are considered as the most environmentally friendly alternatives for satisfying future hydrogen demand. Biohydrogen production from agricultural and agro-industrial solid waste and wastewater is considered as highly advantageous as materials of this kind are abundant, cheap and biodegradable. The combustion of H2 with oxygen produces water as its only product: Unlike other fuels, the combustion of H2 does not produce carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), hydrocarbons or particulate matter (PM). Therefore, hydrogen is an environmentally friendly fuel where endeavors focus on producing specially designed internal combustion engines that can use H2 as fuel. The results showed that laser irradiated inoculum increased biohydrogen production by 1.2 times of the control. Therefore, in this research, it was hypothesized that exposing purple non-sulfur bacterial (PNSB) mix consortium to Helium-Neon red laser for 2 hours increased cell activity and consequently the biohydrogen production from food wastes through photo-fermentation process.