Enhancement of Biogas Production from Macroalgae Ulva latuca via Ozonation Pretreatment

Mohamed A Hassaan,Amany El Sikaily,Ahmed Eleryan,Antonio Pantaleo,Safaa Ragab,Ahmed El Nemr,Marwa R Elkatory

doi:10.3390/en14061703

Abstract

One of the dominant species of green algae growing along the Mediterranean coast of Egypt is Ulva lactuca. Pretreatment can have a major effect on biogas production because hydrolysis of the algae cell wall structure is a rate-limiting stage in the anaerobic digestion (AD) process. The use of ozone, a new pretreatment, to boost biogas production from the green algae Ulva lactuca was investigated in this study. Ozonation at various dosages was used in contrast to untreated biomass, and the effect on the performance of subsequent mesophilic AD using two separate inoculums (cow manure and activated sludge) was examined. The findings indicated that, in different studies, ozonation pretreatment showed a substantial increase in biogas yield relative to untreated algae. With an ozone dose of 249 mg O3 g–1 VS algal for Ulva lactuca, the highest biogas output (498.75 mL/g VS) was achieved using cow manure inoculum. The evaluation of FTIR, TGA, SEM, and XRD revealed the impact of O3 on the structure of the algal cell wall and integrity breakage, which was thus established as the main contributor to improving the biogas production.

Highlights

IntroductionIn anaerobic digestion (AD) [3,4], energy crops, agricultural runoff, manure, sewage sludge, waste oils, animal fat, food scraps, wastewater, and a number of high organic industrial effluents can be used
Compared to raw Ulva lactuca in the peaks at 1035–1627 cm–1 and the wide band at 3288 cm–1, the decrease in the strength range of pretreated algae indicates that the pretreated Ulva lactuca chemical structure deforms as a result of the treatment of lignocellulose by ozonation degradation [41,42,43]
The biomass of the green algae Ulva lactuca was pre-treated with ozonation at various doses in order to increase its digestibility for biogas production in this study

Summary

Introduction

In AD [3,4], energy crops, agricultural runoff, manure, sewage sludge, waste oils, animal fat, food scraps, wastewater, and a number of high organic industrial effluents can be used. Biofuels of the first generation were produced from food, such as grain, maize, or soybeans, resulting in food-energy competition problems and high demand for land [5]. The second generation of biofuels were made from rich lignocellulosic feedstocks, which required complicated pretreatment and expensive catalysts; such processes are expensive and offer little market advantage over fossil fuels [6]. Marine biomass has relatively high yields compared to lignocellulosic feedstocks [7] and removes algae from the body of water, or eutrophication of lakes, rivers, and oceans can be minimized by the beach [8]. Ulva lactuca belongs to the family of green algae and, on the rocky shores of Alexandria in the Mediterranean Sea, is one of the dominant species

Methods

Results

Conclusion