Effect of Low-Temperature Conditioning of Excess Dairy Sewage Sludge with the Use of Solidified Carbon Dioxide on the Efficiency of Methane Fermentation

Abstract

This study aimed to determine the effect of the low-temperature conditioning of excess dairy sewage sludge using solidified carbon dioxide on the efficiency of methane fermentation. An increase in the solidified carbon dioxide to excess dairy sewage sludge volumetric ratio above 0.3 had no significant effect on chemical oxygen demand concentration in the dissolved phase. The highest chemical oxygen demand values, ranging from 490.6 ± 12.9 to 510.5 ± 28.5 mg·dm−3, were determined at solidified carbon dioxide to excess dairy sewage sludge ratio ranging from 0.3 to 0.5. The low-temperature conditioning caused ammonia nitrogen concentration to increase from 155.2 ± 10.2 to 185.9 ± 11.1 mg·dm−3 and orthophosphates concentration to increase from 198.5 ± 23.1 to 300.6 ± 35.9 mg·dm−3 in the dissolved phase. The highest unitary amount of biogas, reaching 630.2 ± 45.5 cm3·g o.d.m.−1, was produced in the variant with the solidified carbon dioxide to excess dairy sewage sludge volumetric ratio of 0.3. Methane content of the biogas produced was at 68.7 ± 1.5%. Increased solidified carbon dioxide dose did not lead to any significant changes in biogas and methane production. The efficiency of biogas production from unconditioned excess dairy sewage sludge was lower by 43.0 ± 3.2%. The analysis demonstrated that the low-temperature conditioning is an energetic viable technology aiding the methane fermentation process.

The Effect of Static Magnetic Field on Methanogenesis in the Anaerobic Digestion of Municipal Sewage Sludge

“…[18,19]. There are several pretreatment methods, including for example: mechanical method [20]; high-pressure method [21]; microwave pretreatment [22]; ultrasound energy pretreatment [23]; thermal methods, including heat treatment and freezing/defrosting [24], or low-temperature disintegration [25]; chemical methods, including acidification [26], alkalization [27], ozonation [28], and oxidation technique [29]; as well as biological methods [30]. Coupled disintegration methods, called the hybrid methods, are employed as well [31].…”

Local Wastewater Treatment Plant for Dairy Production: Challenges and Solutions

“…When designing local dairy wastewater treatment plants, as a rule, drum screens with a perforated fabric and a small gap (1-3 mm) are used, as in such wastewater will not have large inclusions that can damage this equipment. The use of a grease trap designed to separate fat impurities from the effluent is not always justified at local dairy wastewater treatment plant due to the low-fat content (about 20-30 mg/l) [29].…”

“…As a result, it can lead to disruption of the main treatment stage at dairy wastewater treatment plant -biological. This is due to high levels of nitrogen-and phosphorus-containing compounds in whey, which can lead to an increase in the number of filamentous bacteria, inhibition biochemical processes or even death of activated sludge (biocenosis) [29,30].…”

Microwave Radiation Influence on Dairy Waste Anaerobic Digestion in a Multi-Section Hybrid Anaerobic Reactor (M-SHAR)

“…The dairy industry generates waste that is harmful to the environment by way of its properties and characteristics. High contents of its organic and biogenic compounds are particularly problematic [1,2]. It is estimated that one liter of processed milk can generate up to 10 dm 3 of effluent [3].…”