Effect of Acid Whey Pretreatment Using Ultrasonic Disintegration on the Removal of Organic Compounds and Anaerobic Digestion Efficiency

Abstract

Acid whey is a by-product of the dairy industry that should be utilized or appropriately neutralized. Anaerobic processes represent a group of prospective methods for whey processing, and a key priority in their development is to improve their technological and economical effectiveness. The present study aimed to determine the effect of ultrasonic disintegration (UD) of acid whey on the course and effectiveness of methane fermentation. The study results demonstrated that extending the UD duration resulted in increased concentrations of dissolved forms of COD and TOC, efficiency of organic matter biodegradation, and CH4 production. The best effects were achieved at 900 s US, including CH4 production of 0.203 ± 0.01 dm3/gCODin. and CH4 content accounting for 70.9 ± 2.8%. Organic compounds were removed with the following efficiencies: COD—78.7 ± 2.1%, TOC—80.2 ± 1.3%, and BOD5—84.1 ± 1.6%. The highest net energy gain of 5.763 Wh was achieved upon UD of 300 s. Extension of UD time had no significant effect on the improvement in the energetic effectiveness of anaerobic digestion. A strong positive correlation was found between COD and TOC concentrations in the dissolved phase and CH4 production yield.

The Use of Hydrodynamic Cavitation to Improve the Anaerobic Digestion of Waste from Dairy Cattle Farming—From Laboratory Tests to Large-Scale Agricultural Biogas Plants

“…The experimental work carried out in S1 confirmed the fact, repeatedly confirmed in the literature, that there are relationships between the concentration of dissolved organic matter in the substrate and AD efficiency [93,94]. This is confirmed by the work of Lu et al (2018) [93], who used alkaline-ultrasound pretreatment of WAS in AD.…”

“…Linear Pearson correlations confirmed the relationship between the absorbed dose and the concentration of dissolved organic matter [93]. Other studies by the authors concerned the use of ultrasonic disintegration for the pretreatment of acid whey [94]. The results of the correlation analysis of the duration of the UD with the concentration of dissolved organic compounds showed strong, statistically significant correlations for all tested technological variants, which differed in the absorbed dose applied to the substrate.…”

“…In the study by Zupanc et al (2023) [68], which aimed to increase CH 4 production from WAS as a result of HC disintegration, Pearson correlations also confirmed positive or negative relationships between physicochemical changes and CH 4 production [68]. In the authors' study [94] on the use of ultrasonic disintegration for the pretreatment of acid whey, very strong positive correlations were found between COD and TOC concentrations and CH 4 production efficiency, as shown by the coefficient of determination R 2 = 0.9995 and R 2 = 0.9746, respectively. A strong positive correlation was also observed between the duration of UD and gross energy gain (R 2 = 0.8986).…”

“…The results of the correlation analysis of the duration of the UD with the concentration of dissolved organic compounds showed strong, statistically significant correlations for all tested technological variants, which differed in the absorbed dose applied to the substrate. The coefficients of determination calculated for the correlations UD/COD and UD/TOC reached R 2 = 0.8908 and R 2 = 0.7851, respectively [94].…”

Ultrasonic Disintegration to Improve Anaerobic Digestion of Microalgae with Hard Cell Walls—Scenedesmus sp. and Pinnularia sp.

“…Ultrasonic treatment has been one of the methods used to this end [ 34 ]. This form of pre-treatment has been proven effective as a first round of processing before digestion of sludge [ 35 ], plant biomass [ 36 ], and dairy waste [ 37 ]. Ultrasonics have also been used to disinfect water [ 38 ], remove ammonia from wastewater [ 39 ], and support membrane filtration [ 40 ].…”