Recovery of Household Waste by Generation of Biogas as Energy and Compost as Bio-Fertilizer—A Review

Nowadays, organic waste and especially household waste represents a significant global issue due to population growth. The anaerobic digestion (AD) process is an essential operation contributing powerfully to the valorization of organic waste including food waste in terms of renewable energy generation (biogas) and the rich-nutrient residue that can be utilized as bio-fertilizer. Thus, this process (AD) allows for good recovery of household waste by generating biogas and compost. However, the AD operation has been affected by several key factors. In this paper, we aim to involve different critical parameters influencing the AD process, including temperature, pH, organic loading rate (OLR), carbon to nitrogen ratio (C/N), and total solid content (TS(%)). Further, the paper highlights the inhibition caused by the excessive accumulation of volatile fatty acids (VFAs) and ammoniac, which exhibits the positive effects of co-digestion, pretreatment methods, and mixing techniques for maintaining process stability and enhancing biogas production. We analyze some current mathematical models explored in the literature, such as distinct generic, non-structural, combined, and kinetic first-order models. Finally, the study discusses challenges, provides some possible solutions, and a future perspective that promises to be a highly useful resource for researchers working in the field of household waste recovery for the generation of biogas.

Optimization of Biomethane Production via Fermentation of Chicken Manure Using Marine Sediment: A Modeling Approach Using Response Surface Methodology

In this study, marine sediment (MS) was successfully used as a source of methanogenic bacteria for the anaerobic digestion (AD) of chicken manure (CM). Using MS showed high production in liquid and semi-solid conditions. Even in solid conditions, 169.3 mL/g volatile solids of chicken manure (VS-CM) was produced, despite the accumulation of ammonia (4.2 gNH3-N/kg CM). To the best of our knowledge, this is the highest methane production from CM alone, without pretreatment, in solid conditions (20%). Comparing MS to Ozouh sludge (excess activated sewage sludge) (OS), using OS under semi-solid conditions resulted in higher methane production, while using MS resulted in more ammonia tolerance (301 mL/gVS-CM at 8.58 gNH3-N/kg). Production optimization was carried out via a response surface methodology (RDM) model involving four independent variables (inoculum ratio, total solid content, NaCl concentration, and incubation time). Optimized methane production (324.36 mL/gVS-CM) was at a CM:MS ratio of 1:2.5 with no NaCl supplementation, 10% total solid content, and an incubation time of 45 days.

Photochromic Microcapsules for Textile Materials by Spray Drying—Part 1: Production and Characterization of Photochromic Microcapsules

This study, which is the first in a three-part series, deals with the encapsulation of photochromic dyes by spray drying. An aqueous ethyl cellulose dispersion and a spirooxazine-based photochromic dye were used as a shell and core material, respectively. The effects of main encapsulation parameters, such as solvent type, inlet temperature, feed rate, solid content, and aspirator rate were investigated. The encapsulation results were evaluated by scanning electron microscopy (SEM) images, particle size measurements, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The microcapsules obtained from a water-ethanol mixture exhibited photochromic properties. For microcapsule production, the optimum feed rate, total solid content, and aspirator rate were determined. Capsule formation improved with increased inlet air temperature. Spray drying to produce photochromic microcapsules could be a practical method for production of photochromic smart textiles.

Genome-Wide Identification and Analysis of Small Nucleolar RNAs and Their Roles in Regulating Latex Regeneration in the Rubber Tree (Hevea brasiliensis)

Small nucleolar RNAs (snoRNAs) are a class of conserved nuclear RNAs that play important roles in the modification of ribosomal RNAs (rRNAs) in plants. In rubber trees, rRNAs are run off with latex flow during tapping and need to be regenerated for maintaining the functions of the laticifer cells. SnoRNAs are expected to play essential roles in the regeneration of rRNAs. However, snoRNAs in the rubber tree have not been sufficiently characterized thus far. In this study, we performed nuclear RNA sequencing (RNA-seq) to identify snoRNAs globally and investigate their roles in latex regeneration. We identified a total of 3,626 snoRNAs by computational prediction with nuclear RNA-seq data. Among these snoRNAs, 50 were highly expressed in latex; furthermore, the results of reverse transcription polymerase chain reaction (RT-PCR) showed the abundant expression of 31 of these snoRNAs in latex. The correlation between snoRNA expression and adjusted total solid content (TSC/C) identified 13 positively yield-correlated snoRNAs. To improve the understanding of latex regeneration in rubber trees, we developed a novel insulated tapping system (ITS), which only measures the latex regenerated in specific laticifers. Using this system, a laticifer-abundant snoRNA, HbsnoR28, was found to be highly correlated with latex regeneration. To the best of our knowledge, this is the first report to globally identify snoRNAs that might be involved in latex regeneration regulation and provide new clues for unraveling the mechanisms underlying the regulation of latex regeneration.

An Index for Quantitative Evaluation of the Mixing in Ethanol Precipitation of Traditional Chinese Medicine

(1) Background: Ethanol precipitation is widely used in the manufacturing traditional Chinese medicines (TCMs). Insufficient mixing of ethanol solution and concentrate usually results in the coating loss of active ingredients. However, there is no index for quantitative evaluation of the mixing in ethanol precipitation. Therefore, this study aimed to define an index for quantitative evaluation of the mixing effect in ethanol precipitation of TCMs. (2) Methods: The concept and requirements of a mixing indicator were proposed. The mass percentage of concentrate fully mixed with ethanol solution (well-mixing ratio, WMR) was used as an index to evaluate the mixing effect. The formula for calculation of WMR was derived. The utility of the WMR was evaluated on stirring devices and a micromesh mixer. (3) Results: Increasing stirring speed, decreasing total solid content of the concentrate, and decreasing the diameter of the ethanol solution droplets all resulted in higher retention rates for lobetyolin and higher WMR. The WMR increased with the increasing flow rate of the concentrate and ethanol solution in the micromesh mixer. The mixing of ethanol solution and concentrate was better when using a micromesh mixer with a smaller internal mixing zone. The results revealed that WMR could be used to quantitatively characterize the mixing of concentrate and ethanol solution, although it has some limitations. (4) Conclusions: The proposed index WMR could guide quality control of the TCM ethanol precipitation process. This study represents a new contribution to improving ethanol precipitation equipment, optimizing process parameters, and enhanced properties of concentrate for TCM enterprises.

Volatile Fatty Acid Production from Food Waste Leachate Using Enriched Bacterial Culture and Soil Bacteria as Co-Digester

The production of volatile fatty acids (VFAs) from waste stream has been recently getting attention as a cost-effective and environmentally friendly approach in mechanical–biological treatment plants. This is the first study to explore the use of a functional bacterium, AM5 isolated from forest soil, which is capable of enhancing the production of VFAs in the presence of soil bacteria as a co-digester in non-strict anaerobic fermentation processes of food waste leachates. Batch laboratory-scale trials were conducted under thermophilic conditions at 55 °C and different pH values ranging from approximately 5 to 11, as well as under uncontrolled pH for 15 days. Total solid content (TS) and volatile solid content (VS) were observed with 58.42% and 65.17% removal, respectively. An effluent with a VFA concentration of up to 33,849 mg/L (2365.57 mg/g VS; 2244.45 mg/g chemical oxygen demand (COD)-VFA VS; 1249 mg/g VSremoved) was obtained at pH 10.5 on the second day of the batch culture. The pH resulted in a significant effect on VFA concentration and composition at various values. Additionally, all types of VFAs were produced under pH no-adjustment (approximately 5) and at pH 10.5. This research might lead to interesting questions and ideas for further studies on the complex metabolic pathways of microbial communities in the mixture of a soil solution and food waste leachate.

PREPARATION AND CHARACTERIZATION OF SPECIALTY NATURAL RUBBER LATEX CONCENTRATE

ABSTRACT Conventionally, specialty natural rubber (SpNR) latex, namely, deproteinized natural rubber (DPNR) latex and epoxidized natural rubber (ENR) latex, are prepared from low ammonia latex (LATZ) causing high material cost. To address this issue, the objective of this study is to prepare SpNR latex directly from freshly tapped NR latex. In this work, DPNR latex is prepared via a heat enzymatic hydrolysis process, while ENR latex is prepared via in situ epoxidation chemical modification process. In addition, both DPNR and ENR latex were concentrated to 60% total solid content via ultrafiltration process using membrane separation technology. Physiochemical properties of DPNR, ENR, and LATZ latex were compared. Results show that the total solid content, dry rubber content, and alkalinity level of the latexes achieved the targeted value. This study also found that nitrogen content of DPNR latex, LATZ latex, and ENR latex were at 0.11%, 0.29%, and 0.25%, respectively, indicating successful deproteinization of the DPNR latex. On the other hand, the epoxidation level of ENR latex produced in this study was at 46.3%, which is slightly lower than the targeted level of 50%. Rheological studies found that ENR latex exhibits the highest viscosity, followed by DPNR and LATZ, but all show characteristic shear-thinning behavior. This study also found that LATZ and DPNR latex are more liquid-like in nature, while ENR latex behaves more like an elastic solid. Non-ionic surfactants play a major role in influencing flow and deformation behavior of the ENR and DPNR latex.

Formulation and Standardization of Asava from Carica papaya

Asava and Arishta are alcoholic medicaments prepared by allowing the herbal juices or their decoctions to undergo fermentation with the addition of sugar. Standardization of ayurvedic formulation is important so as to assess the standard of medication. Within the present study standardization of asava from fruit tree Carica papaya, known to be effective in Dengue fever, Cancer cell growth inhibition, Antimalarial has been performed. Asava formulation was prepared by the normal method of Ayurveda. The formulation has been standardized by modern scientific control procedures for the finished products. Standardization of asava was achieved by organoleptic study, physicochemical parameters like PH, denseness, total solid content, amount, alcohol content, index of refraction, total reducing sugars, and stability study. The results have revealed that the physicochemical parameters were within the bounds and also the values may be wont to establish and formulate procedures for standardization and quality controlling of those ayurvedic formulations.