Feeding frequency efficacy on biogas yield of oily substrate anaerobic digestion in continuous stir tank reactor.

Anaerobic treatment of oily substrate, known as grease trap waste (GTW), was investigated for its practicability via continuous stirred tank reactor (CSTR) at different operating conditions and selected recovery strategies of feeding frequency efficacy. This study determine the performance of feeding frequency efficacy, namely feeding every 24 hours (R24H) and feeding every 12 hours (R12H). Under organic loading rate (OLR) of 2.2 gCOD/L.day, R12H exhibited methane composition of 57%, methane production rate of 0.27 LCH4/L.day, and methane yield of 0.14 LCH4/gCODremoved. At the same OLR, R24H recorded methane composition of 60%, methane production rate of 0.29 LCH4/L.day and similar methane yield as R12H. Findings indicated that R24H showed performance comparable to that of R12H. Given minor variation observed in performance, it is recommended that plant operators may consider scheduling two feedings per day for low loading conditions and switch to one feeding per day for higher loading conditions. This strategy is designed to balance the system and prevent shock loads, which could lead to plant shutdowns. This mechanism will induce their conversion to volatile fatty acids (VFAs); thus, reducing the risk of acid accumulation and pH drops, which could inhibit methanogens to produce methane, especially for oily substrate.

Kinetic evaluation of sonicated food waste in continuously stirred tank reactor.

This work aimed to evaluate the process performance and stability of the anaerobic digestion of sonicated food waste (SFW) by determining the kinetic parameters using Monod, Contois, Modified Stover-Kincannon, and Grau second-order multicomponent substrate removal kinetic models. The anaerobic digestion was conducted on the sonicated food waste (SFW) in a 13 L continuously stirred tank reactor (CSTR) with a stepwise organic loading rate (OLR) ranging from 1.5 to 3.5 gCOD/L.day. The experimental works were carried out in two stages (start-up then followed by semi-continuous). The ultrasonic pretreatment was performed by sonicating the food waste slurry for 10 minutes at a 20 kHz frequency and specific energy input of 25,997 kJ/kg TS. The process performance, as well as acceptable stability in the SFW digester, provided satisfactory predictions with Monod, Modified Stover-Kincannon, Grau second-order multicomponent substrate removal, and Contois kinetic models. A significant relationship was seen between the predicted and experimental data with correlation coefficients (R2) ranging from 0.893 to 0.996. In this study, the Monod model with R2 = 0.996 indicates the most suitable model for understanding the kinetic parameters of the anaerobic system in the CSTR which digests the sonicated food waste (SFW) slurry.

Screening of Suitable Ionic Liquids as Green Solvents for Extraction of Eicosapentaenoic Acid (EPA) from Microalgae Biomass Using COSMO-RS Model.

Omega-3 poly unsaturated fatty acids (PUFA) particularly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have many health benefits including reducing the risk of cancer and cardiovascular disease. Recently, the use of ionic liquids (ILs) in lipid extraction from microalgae provides the potential to overcome common drawbacks, offers several other benefits. To date, very limited researches are available to focus on extracting microalgae lipid and PUFA in particular by using ILs. The objective of current work is to screen the potential ILs that can be applied in EPA extraction. In this study, fast ILs screening was performed with the help of a conductor like screening model for real solvents (COSMO-RS) and the ILs with higher capacity values for use in extraction of EPA were compared. According to the results, the highest capacity for EPA extraction among 352 screened cation/anion combinations belongs to [TMAm][SO4]. It is expected to achieve a higher yield of EPA once applying this combination as the solvent in the process of extraction. ILs with small anions were observed to have higher capacities, as well possessing higher charge density compared to larger ones, and therefore, they are more preferable for extraction purposes. Moreover, shorter alkyl chain cations are preferred when using imidazolium-based IL, which agrees with experimental data.