Production of methane by co-digestion of cassava pulp with various concentrations of pig manure

Cassava pulp is a major by-product produced in a cassava starch factory, containing 50–60% of starch (dry basis). Therefore, in this study we are considering its potential as a raw material substrate for the production of methane. To ensure sufficient amounts of nutrients for the anaerobic digestion process, the potential of co-digestion of cassava pulp (CP) with pig manure (PM) was further examined. The effect of the co-substrate mixture ratio was carried out in a semi-continuously fed stirred tank reactor (CSTR) operated under mesophilic condition (37 °C) and at a constant OLR of 3.5 kg VS m^?3 d^?1 and a HRT of 15 days. The results showed that co-digestion resulted in higher methane production and reduction of volatile solids (VS) but lower buffering capacity. Compared to the digestion of PM alone, the specific methane yield increased 41% higher when co-digested with CP in concentrations up to 60% of the incoming VS. This was probably due to an increase in available easily degradable carbohydrates as the CP ratio in feedstock increased. The highest methane yield and VS removal of 306 mL g^?1 VS_added and 61%, respectively, were achieved with good process stability (VFA:Alkalinity ratio < 0.1) when CP accounted for 60% of the feedstock VS. A further increase of CP of the feedstock led to a decrease in methane yield and solid reductions. This appeared to be caused by an extremely high C:N ratio of the feedstock resulting in a deficiency of ammonium nitrogen for microbial growth and buffering capacity.     

Hydrogen production from alcohol distillery wastewater containing high potassium and sulfate using an anaerobic sequencing batch reactor

In this study, the feasibility of hydrogen production from alcohol distillery wastewater containing high potassium and sulfate was investigated using an anaerobic sequencing batch reactor (ASBR). The seed sludge taken from an anaerobic tank treating the distillery wastewater was boiled for 15 min before being fed to the ASBR. The ASBR system was operated under different feed chemical oxygen demand (COD) values and different COD loading rates at a mesophilic temperature of 37 °C, a controlled pH at 5.5, and a cycle time of 6 cycles per day. When the studied ASBR was operated under the best conditions (providing a maximum hydrogen production efficiency) of a feed COD of 40,000 mg/l, a COD loading rate of 60 kg/m³ d, and a hydraulic retention time of 16 h, the produced gas was found to contain 34.7% H₂ and 65.3% CO_2, without any methane being detected. Under these best conditions, the specific hydrogen production rate (SHPR) of 270 ml H₂/g MLVSS d (or 3310 ml H₂/l d), and hydrogen yield of 172 ml H₂/g COD removed, were obtained. When the feed COD exceeded 40,000 mg/l, the process performance in terms of hydrogen production decreased because of the potassium and sulfate toxicity.     

Poly(acrylic acid)-grafted magnetic nanoparticle for conjugation with folic acid

Poly(acrylic acid) (poly(AA))-grafted magnetite nanoparticles (MNPs) prepared via surface-initiated atom transfer radical polymerization (ATRP) of t-butyl acrylate, followed by acid-catalyzed deprotection of t-butyl groups, is herein presented. In addition to serve as both steric and electrostatic stabilizers, poly(AA) grafted on MNP surface also served as a platform for conjugating folic acid, a cancer cell targeting agent. Fourier transform infrared spectroscopy (FTIR) was used to monitor the reaction progress in each step of the syntheses. The particle size was 8 nm in diameter without significant aggregation during the preparation process. Photocorrelation spectroscopy (PCS) indicated that, as increasing pH of the dispersions, their hydrodynamic diameter was decreased and negatively charge surface was obtained. According to thermogravimetric analysis (TGA), up to 14 wt% of folic acid (about 400 molecules of folic acid per particle) was bound to the surface-modified MNPs. This novel nanocomplex is hypothetically viable to efficiently graft other affinity molecules on their surfaces and thus might be suitable for use as an efficient drug delivery vehicle particularly for cancer treatment.     

Nylon fibers as supporting media in anaerobic hybrid reactors: it's effects on system's performance and microbial distribution

The performances of three anaerobic hybrid reactors with various nylon fiber densities per packed bed volume (33, 22, and 11 kg/m(3) in R1, R2, and R3, respectively) as supporting media were evaluated through their ability to remove organic compounds in cassava starch wastewater. In addition, the distributions of non-methanogenic and methanogenic population in the reactors were investigated. During a 6-month operation, the organic loading rate was increased in stepwise from 0.5 to 4.0 kg COD/m3/day and the hydraulic retention time (HRT) shortened to 5.4 days. The COD removal efficiency was more favorable in R1 (87%) and R2 (84%) than in R3 (70%). The total biomass in the reactors with greater nylon fiber densities was also higher and increased from 20.4 to 67.3 g VSS and to 57.5 g VSS in R1 and R2, respectively. When the HRT was further shortened to 3 days, however, the efficiency of both reactors demonstrated a declining trend and reached 74% in R1 and 61% in R2. The distribution of microbial populations involved in the reactors was determined using the Most Probable Number technique. The result showed the lowest number of methanogens in R3 which correlated well to its relatively low efficiency. The number of non-methanogens in all reactors was, nonetheless, comparable. By shortening the HRT to 3 days, the methanogenic population in R2 diminished in both attached and suspended biomass whereas a slight reduction was detected only in the attached biomass of R1.     

Influence of SCN− moiety on CH3NH3PbI3 perovskite film properties and the performance of carbon-based hole-transport-layer-free perovskite solar cells

Journal of Materials Science: Materials in Electronics - CH3NH3PbI3 perovskite films were prepared via a hot-casting method using six different CH3NH3I, PbI2 and Pb(SCN)2 solutions. Surface...     

Determination of nitrofurans residues in animal feeds by flow injection chemiluminescence procedure

A simple flow injection chemiluminescence (FI-CL) method was developed for the rapid and sensitive determination of nitrofurans, including furazolidone, nitrofurantoin and nitrofurazone, in animal feeds based on its chemiluminescence induced by potassium permanganate in sulphuric acid medium. The method involves the injection of nitrofuran samples or standards into H₂SO₄ carrier stream, which then merges at a T-piece with a reagent stream consisting of KMnO₄ in the H₂SO₄ carrier solution. The elicited chemiluminescence intensity of the resulting reaction mixture was measured by photomultiplier tube operated at a voltage of 950 V. Optimum CL signals were given using 2.5 × 10⁻⁵ mol L⁻¹ potassium permanganate in 0.1 mol L⁻¹ sulphuric acid as an oxidant stream and a carrier stream of 0.1 mol L⁻¹ sulphuric acid with a total flow rate of 7.0 mL min⁻¹. Results detailing the optimisation of the analytical signal, calibration, and common interferences of animal feeds were also discussed. The proposed FI-CL method was successfully applied to the determination of nitrofurans in animal feeds, with excellent recoveries, as the determination is free from interference. The method validation has been compared versus HPLC method for animal feed samples.     

Critical effect of oxygen on aroma compound production by Proteus vulgaris

Aroma compound production by Proteus vulgaris was studied in a liquid medium under two culture conditions, static or shaken. By using a dynamic headspace technique coupled with gas chromatography–mass spectrometry, 30 volatile components, aldehydes, alcohols, esters, ketones, sulphur compounds and other miscellaneous compounds were identified. P. vulgaris produced a variety of volatile compounds in different amounts, depending on its culture condition. Sensory analysis has shown that the aroma characteristics of each culture condition were clearly differently perceived. The volatile composition was in agreement with the aroma perception. The culture medium obtained without agitation was characterised by a sulphur/rotten egg note and by a high level of H₂S. The culture medium obtained with agitation was characterised by fruity/fresh and cheese notes and by a high level of alcohols and volatile sulphur compounds. Thus, P. vulgaris could be a useful microorganism to produce various and numerous natural aroma compounds, depending on the culture conditions during fermentation.