Evaluation of batch mesophilic anaerobic digestion of raw and trampled llama and dromedary dungs: methane potential and kinetic study

This research was carried out with the aim to evaluate the anaerobic digestion (AD) of llama and dromedary dungs (both untreated and trampled) in batch mode at mesophilic temperature (35 °C). The biochemical methane potential (BMP) tests with an inoculum to substrate ratio of 2:1 (as volatile solids (VS)) were carried out. The methane yield from trampled llama dung (333.0 mL CH4 g−1 VSadded) was considerably higher than for raw llama, raw and trampled dromedary dungs (185.9, 228.4, 222.9 mL CH4 g−1 VSadded, respectively). Therefore, trampled llama dung was found to be the best substrate for methane production due to its high content of volatile solids as well as its high nitrogen content (2.1%) and more appropriate C/N ratio (23.6) for AD. The experimental data was found to be in accordance with both first-order kinetic and transference function mathematical models, when evaluating the experimental methane production against time. By applying the first-order kinetic model, the hydrolysis rate constants, kh, were found to be 19% and 11% higher for trampled dungs in comparison with the raw dung of dromedary and llama, respectively. In addition, the maximum methane production rate (Rm) derived from the transference function model for trampled llama dung (22.0 mL CH4 g−1 VS d−1) was 83.3%, 24.4% and 22.9% higher than those obtained for raw llama manure and for raw and trampled dromedary dungs, respectively.

Effect of Engineered Biomaterials and Magnetite on Wastewater Treatment: Biogas and Kinetic Evaluation

In this study, the principle of sustaining circular economy is presented as a way of recovering valuable resources from wastewater and utilizing its energy potential via anaerobic digestion (AD) of municipality wastewater. Biostimulation of the AD process was investigated to improve its treatability efficiency, biogas production, and kinetic stability. Addressing this together with agricultural waste such as eggshells (CE), banana peel (PB), and calcined banana peels (BI) were employed and compared to magnetite (Fe3O4) as biostimulation additives via 1 L biochemical methane potential tests. With a working volume of 0.8 L (charge with inoculum to substrate ratio of 3:5 v/v) and 1.5 g of the additives, each bioreactor was operated at a mesophilic temperature of 40 °C for 30 days while being compared to a control bioreactor. Scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis was used to reveal the absorbent’s morphology at high magnification of 10 kx and surface pore size of 20.8 µm. The results showed over 70% biodegradation efficiency in removing the organic contaminants (chemical oxygen demand, color, and turbidity) as well as enhancing the biogas production. Among the setups, the bioreactor with Fe3O4 additives was found to be the most efficient, with an average daily biogas production of 40 mL/day and a cumulative yield of 1117 mL/day. The kinetic dynamics were evaluated with the cumulative biogas produced by each bioreactor via the first order modified Gompertz and Chen and Hashimoto kinetic models. The modified Gompertz model was found to be the most reliable, with good predictability.

Biogas Production from Sugarcane Vinasse: A Review

Biogas is a renewable energy sources that could replace the role of fossil fuel. Biogas could be produced from biomass or agro-industrial wastewater. Sugarcane vinasse has potential of biogas production due to its high BOD concentration (10–65 g BOD/l). However, the biogas production from sugarcane vinasse has several drawbacks that hinders the maximum biogas yield, such as: acidic pH (pH 3.5 – 5.0), high temperature (80–90°C) and high concentration of sulfuric acid (> 150 mg/L). Theoretically, the methane potential per gram COD is 0.35 L/gr COD, containing of 60% methane. However, up to date, the maximum biogas production from vinasse was less then its theoretical value. To get the full potential of biogas production from vinasse wastewater as well as to reduce the capital cost for full scale application, combination of suitable pre-treatment, selected microorganisms and bioreactor design-configuration are the most important parameters to be considered. This paper aims to explore the potential of sugarcane vinasse to produce biogas, by elaborating the aforementioned key parameters. In this review the basic characteristic and the potency of sugarcane vinasse wastewater will be elaborated. Furthermore, the effect of key parameters such as pH, temperature, and organic load to biogas production will also be discussed. The biogas technology will also be explored. Lastly, conclusion will be determined

The Influence of Low-Temperature Food Waste Biochars on Anaerobic Digestion of Food Waste

The proof-of-the-concept of application of low-temperature food waste biochars for the anaerobic digestion (AD) of food waste (the same substrate) was tested. The concept assumes that residual heat from biogas utilization may be reused for biochar production. Four low-temperature biochars produced under two pyrolytic temperatures 300 °C and 400 °C and under atmospheric and 15 bars pressure with 60 minutes retention time were used. Additionally, the biochar produced during hydrothermal carbonization (HTC) was tested. The work studied the effect of a low biochar dose (0.05 gBC x gTSsubstrate-1, or 0.65 gBC x L-1) on AD batch reactors’ performance. The biochemical methane potential test took 21 days and the process kinetics using the first-order model were determined. The results showed that biochars obtained under 400°C with atmospheric pressure and under HTC conditions improve methane yield by 3.6%. It has been revealed that thermochemical pressure influences the electrical conductivity of biochars. The biomethane was produced with a rate (k) of 0.24 d-1, and the most effective biochars increased the biodegradability of FW to 81% in comparison to variants without biochars (75%).

Potensi Limbah Cair Batik sebagai Sumber Bioenergi (Studi Kasus di UKM Batik Blimbing Malang)

Batik merupakan salah satu produk kebanggaan bangsa Indonesia, yang umumnya diproduksi oleh usaha kecil menengah (UKM). Peningkatan permintaan batik mendorong adanya peningkatan jumlah UKM batik serta jumlah limbah cair batik yang dihasilkan. Masih banyak UKM batik yang membuang limbah cairnya langsung ke lingkungan yang berpotensi menimbulkan pencemaran pada tanah dan air. Hal ini disebabkan oleh belum adanya fasilitas pengolahan limbah yang memadai, sesuai dengan kondisi yang dialami oleh UKM Batik Blimbing Malang. Penelitian ini bertujuan untuk mengidentifikasi potensi pengolahan limbah cair batik secara anaerobik untuk memproduksi biogas sebagai sumber energi terbarukan. Pada penelitian ini digunakan teknologi anaerobic digestion yang dioperasikan secara batch dengan kondisi mesofilik (37 °C) tanpa pengadukan, dikenal sebagai uji biochemical methane potential (BMP) dengan waktu pengamatan selama 28 hari. Sampel yang diuji meliputi penambahan 100% limbah cair batik dengan berbagai variasi volume. Hasil penelitian menunjukkan bahwa limbah cair batik memiliki kandungan bahan pencemar organik yang tinggi, yaitu sebesar 8.651 mg/L (BOD) dan 54.700 mg/L (COD). Hasil uji BMP juga menunjukkan rendahnya biogas yang dapat diproduksi dari limbah cair batik. Kondisi ini disebabkan oleh beberapa faktor antara lain tingginya kandungan COD, ammonia, zat pewarna beracun, dan nisbah C/N yang berpengaruh negatif terhadap pertumbuhan mikroorganisme.

Effects of Lipase Addition, Hydrothermal Processing, Their Combination, and Co-Digestion with Crude Glycerol on Food Waste Anaerobic Digestion

To enhance anaerobic fermentation during food waste (FW) digestion, pretreatments can be applied or the FW can be co-digested with other waste. In this study, lipase addition (LA), hydrothermal pretreatment (HTP), and a combination of both methods (HL) were applied to hydrolyze organic matter in FW. Furthermore, the effects of crude glycerol (CG), which provided 5%, 10%, and 15% of the volatile solids (VS) as co-substrate (denoted as CG5, CG10, and CG15, respectively), on the anaerobic digestion of FW were assessed. With an increasing proportion of CG in the co-digestion experiment, CG10 showed higher methane production, while CG15 negatively affected the anaerobic digestion (AD) performance owing to propionic acid accumulation acidifying the reactors and inhibiting methanogen growth. As the pretreatments partially decomposed hard-to-degrade substances in advance, pretreated FW showed a stronger methane production ability compared with raw FW, especially using the HL method, which was significantly better than co-digestion. HL pretreatment was shown to be a promising option for enhancing the methane potential value (1.773 NL CH4/g VS) according to the modified Gompertz model.