Tag Archives: Digestion

Modelling Energy Recovery from Wastewater Treatment by Anaerobic Digestion (Published)

In this study, attempt was made to model gas production process from an anaerobic digestion of sewage sludge in a treatment plant. Apart from the issue of environmental cleanup this process of sewage treatment offers, it has become a viable tool to solving energy problems that exist in many parts of the world. Nigeria has much wastewater and this constitutes environmental pollution when channelled to the freshwaters body. Some wastewater; domestic and industrial, has to be treated before channelling them into waterways and in doing this, biogas can be tapped from the system if anaerobic digesters are designed and incorporated into the treatment plants. In this study, this process of biogas production was modelled to ascertain the amount of energy that can be recovered from wastewater treatment plant, for economic usage in the operation of the treatment plant and municipal consumption. To achieve this objective, equation  was derived and its application yielded a positive result. Results from two different experimental reactors, reactors 1 and 2 (see Table 4.2 above) were used in comparison with the model reactors to investigate performance of the model. Figure 4.1 shows the gas yield for the different reactors investigated. Statistical analysis of the overall results shows that model reactor 1 has a coefficient of correlation (CORR) of 0.95, this demonstrate a good fit with the experimental results obtained from reactor 1. However, a mean absolute percentage error (MAPE) and root mean square error (RMSE) of 2.15 and 7.49 respectively, was recorded during this process. These values indicate a significantly low error of estimates and shows that the model is reliable.Similarly, model reactor 2 gave a CORR of 0.96 with errors of estimate (MAPE) of 1.34 and RMSE OF 3.12. Meanwhile, it can be observed that both experimental reactor 1 and 2 have a slightly higher values of gas yield than their corresponding model reactors. This trend is rather good in relation to safety in gas production estimate using the model. An overestimating model would be misleading and give a false data when such is needed for energy generation design and operation. . The biogas yield obtained  were used to power a micro gas turbine in order to determine electrical energy output from the system, a process that have now been commercialized for economic benefits. Equation 3.24 was derived and its consequent solution, equation 3.27 was used for that purpose. Figure 4.6 shows the energy output for experimental reactor 1. The result obtained shows a close fit between the turbine output and the model output. Precisely, a CORR value of 0.96 was obtained with a small error of estimate of 2.34 and 8.00 respectively for MAPE and RMSE. Similarly, figure 4.7 shows energy output for experimental reactor 2. In this, the coefficient of correlation was found to be 0.94 with MAPE and RMSE being 2.15 and 3.55 respectively. Figure 4.8 and 4.9 shows the energy output for model reactors 1 and 2 respectively. The CORR, MAPE and RMSE were 0.95, 3.78 and 5.51 respectively for model reactor 1 while a similar value of 0.97, 1.73 and 5.02 were recorded for model reactor 2 respectively. In all, a very good correlation values was obtained to show that energy generation from treatment plant can be modelled given the biogas yield data. It should be noted that turbine plant operational mechanism may vary slightly depending on their capacities; consequently, an updated recalibration of the model would be necessary.

Keywords: Anaerobic reactor, Digestion, Energy, Sewage, Treatment.

Biological Viruses are Certainly Living-Things and Switching off Genomic Metabolism (Published)

Biological viruses had been concluded that they were nonliving-things whereas some scientists stated that they were transitional things between living-things and nonliving-things. Biological viruses are very tiny organisms with their diameters in nanometers level. They exist everywhere, such like in air, soil, plant and animal body. Biological viruses consist of a protein shell that is referred to as capsid, and a genome made of DNA or RNA, which is tucked inside the capsid. Depending on the type of species, they may also have an envelope made of lipid membrane. Biological viruses possess the genome that performs transformative, reproductive, perpetuative, speciation, and evolution functions. Having these visible scientific truths in mind, biological viruses are certainly living-things. Biological viruses kill (switch off the genomic metabolism of) their target cells and then their genomic metabolism digests the internal contents of the dead/killed target cells into absorbable monomers so as to transform into viruses of their kind; by sequencing the monomers such as amino acids and nucleotides resulted from digestion of nutritive substances, in the form of viral biomass. In other words, after killing (switching off the genomic metabolism of) a target cell the transformation part involoves: (i) digesting the biological polymer molecules of the target cell into their absorbable monomers, and  (ii) sequencing the absorbable monomers resulted from digestion, in the form of viral polymers that is predetermined by the coded information/directives present in the genome of the virus which entered the target cell. The mechanism of these events is similar to the action of a team of lions which kill (switch off genomic metabolism of) a buffalo before eating the flesh of the killed buffalo in order to transform the flesh (biomass) of buffalo by the genomic metabolism of lions into lions (biomass of lions). The genomic metabolism of the eater organism also transforms the taste & strength of softness for digestibility as a type of flesh (biomass) into the characteristic taste & strength of softness of the eater/predator species’s  biological polymer molecules or flesh. The term genomic metabolism (metabolism of a genome) means a series of chemical reactions between the genome of a living-thing (i.e., of a species) and its nutritive substances in its compatible environment. An individual living-thing is said alive if and only if its genomic metabolism is going on. A dead, killed, or a body with switched off genomic metabolism is a living-thing in which metabolism of a genome has completely stopped and hence, it is not alive but dead/killed. What happens to the dead body of a living-thing is being digested or decomposed into absorbable monomers and or into inorganic compounds for the circulation of materials in the ecosystem. Switching off the genomic metabolism of a biological virus means killing that virus ; switching off the genomic metabolism of a cell means killing that cell; whereas switching off the genomic metabolism of a multicellular prey by a predator means killing that prey (eg., a buffalo is killed by a lion, or an impala is killed by a python). What follows after killing is: (i) digesting the internal polymers of the target cell (if the killer is a biological virus or a single-celled organism) into absorbable monomers and or into inorganic compounds, or (ii) ingesting, and digesting of polymers of the prey (if the killer is a  multicellular organism) into absorbable monomers and or into inorganic compounds for circulation of materials in the ecosystem. Genomic metabolism of a biological virus is capable of killing a single-celled organism directly and a multicellular organism indirectly. 

Keywords: Absorbable Monomers, Alive, Biological Viruses, Dead, Digestion, Genomic Metabolism, Switching off Genomic Metabolism