Bio-organic fertilizer production from industrial waste and insightful analysis on release kinetics.

The present study has been designed to utilize industrial and agricultural solid waste for NPK (Nitrogen-Phosphorus-Potassium) bio-organic fertilizer production and its optimized use. The collagenic material of wet blue leather (WBL) from leather industry was used as nitrogen source, after H3PO4 acid-mediated chromium removal. Chicken meat-bone meal (CMBM) and rice husk ash (RHA) are abundantly available locally, had used as P, K, and Ca sources. The presence of N, P, K, Ca in the produced bio-organic NPK fertilizer were 10.76, 11.03, 3.41, 13.64, respectively as per mixing ratio of ingredients. In this study it was effect on the chili plant (Capsicum annuum L.) growth and revealed 1.15 and 1.03 fold higher plant growth, 1.40 and 1.18 fold higher total chlorophyll content than untreated soil (control), and chemical fertilizer. The liberation of fertilizers components from their source, transport of fertilizer components in the soil, and absorption in plant roots have been studied using mathematical models indicating the optimum fertilizer use for better productivity and to reduce loss of extra fertilizer and eutrophication. The formulation showed excellent water retention capability (3.2 L/kg), which might increase soil water availability to the plants and eventually reduce water demand and labour cost. DNA intercalation study proved there is no harm to use this fertilizer.

Bioelectrosynthesis technology for enhancing methane production using a thermophilic methanogenic consortium.

This work investigated the electrocatalytic activity of a thermophilic methanogenic consortia (TMC) for developing a bioelectrosynthesis process to convert food and paper wastes to methane. Electroanalytical techniques were used to analyze the electrocatalytic activity of the TMC biofilm formed onto the electrodes. The developed electromethanogenesis process enhanced the yield of methane by 54.7% than control experiments. Scanning electron micrographs of the TMC bioelectrodes showed that the electrosynthesis process accelerates biofilm formation onto the electrodes leading to enhanced direct electron transfer reactions at electrode-electrolyte interface. This study will help in developing a novel approach for valorization of food and paper waste to biofuels.

Thermophiles for biohydrogen production in microbial electrolytic cells.

Thermophiles are promising options to use as electrocatalysts for bioelectrochemical applications including microbial electrolysis. They possess several interesting characteristics such as ability to catalyze a broad range of substrates at better rates and over a broad range of operating conditions, and better electrocatalysis/electrogenic activity over mesophiles. However, a very limited number of investigations have been carried out to explore the microbial reactions/pathways and the molecular mechanisms that contribute to better electrocatalysis/electrolysis in thermophiles. Here, we review the electroactive characteristics of thermophiles, their electron transfer mechanisms, and molecular insights behind the choice of thermophiles for bioelectrochemical/electrolytic processes.

Engineering rheology of electrolytes using agar for improving the performance of bioelectrochemical systems.

The present study is focused on enhancing the rheological properties of the electrolyte and eliminating sedimentation of microorganisms/flocs without affecting the electron transfer kinetics for improved bioelectricity generation. Agar derived from polysaccharide agarose (0.05-0.2%, w/v) was chosen as a rheology modifying agent. Electroanalytical investigations showed that electrolytes modified with 0.15% agar display a nine-fold increase in current density (1.2 mA/cm2) by a thermophilic strain (Geobacillus sp. 44C, 60 °C) when compared with the control. Sodium phosphate buffer (0.1 M, pH 7) electrolyte with riboflavin (0.1 mM) was used as the control. Electrolytes modified with 0.15% agar significantly improved chemical oxygen demand removal rates. This developed electrolyte will aid in improving bioelectricity generation in Bioelectrochemical Systems (BES). The developed strategy avoids the use of peristaltic pumps and magnetic stirrers, thereby improving the energy efficiency of the process.

Rewiring the microbe-electrode interfaces with biologically reduced graphene oxide for improved bioelectrocatalysis.

The aim of this work was to study biologically reduced graphene oxide (RGO) for engineering the surface architecture of the bioelectrodes to improve the performance of Bioelectrochemical System (BES). Gluconobacter roseus mediates the reduction of graphene oxide (GO). The RGO modified bioelectrodes produced a current density of 1 mA/cm2 and 0.69 mA/cm2 with ethanol and glucose as substrates, respectively. The current density of RGO modified electrodes was nearly 10-times higher than the controls. This study, for the first time, reports a new strategy to improve the yield as well as efficiency of the BES by wrapping and wiring the electroactive microorganisms to the electrode surfaces using RGO. This innovative wrapping approach will decrease the loss of electrons in the microbe-electrolyte interfaces as well as increase the electron transfer rates at the microorganism-electrode interfaces.

Biohydrogen production from space crew's waste simulants using thermophilic consolidated bioprocessing.

Human waste simulants were for the first time converted into biohydrogen by a newly developed anaerobic microbial consortium via thermophilic consolidated bioprocessing. Four different BioH2-producing consortia (denoted as C1, C2, C3 and C4) were isolated, and developed using human waste simulants as substrate. The thermophilic consortium C3, which contained Thermoanaerobacterium, Caloribacterium, and Caldanaerobius species as the main constituents, showed the highest BioH2 production (3.999 mmol/g) from human waste simulants under optimized conditions (pH 7.0 and 60 °C). The consortium C3 also produced significant amounts of BioH2 (5.732 mmol/g and 2.186 mmol/g) using wastewater and activated sludge, respectively. The developed consortium in this study is a promising candidate for H2 production in space applications as in situ resource utilization.