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The increasing demand of the world energy consumption has made it necessary to shift energy technologies toward renewable energy sources. The sustainability of feedstock can be maintained when utilizing feedstock from waste sources, such as dairy waste, food waste, and others. Dairy waste is one of the cheapest sources available. The compositions of dairy waste scum, including free fatty acids (8–10 %), triglycerides (more than 80 % in dry bases), and fats around 60 %, which have the potential to be used as the feedstock for biodiesel production in the presence of certain catalysts. To ensure more sustainability, the catalyst should be derived from waste (e.g., eggshells and cow bones) that consists of calcium oxide, which can then be used to catalyze the transesterification of dairy waste. This review emphasizes the current production of dairy waste globally and the potential of the waste and other types of organic waste as feedstock for biodiesel production, as well as determines the optimum reaction conditions for high‐quality biodiesel production.

Anaerobic digestion (AD) is one of the renewable technologies and a good alternative for the management of livestock manure. The present study focuses on co-digestion of fresh chicken manure (FCM) with corn stover (CS) experiments for biogas production. The objective of this study is to evaluate the effect of corn stover in the production of biogas and methane content by co-digestion. The mixing ratios of co-digestion of FCM with CS were 1:1, 1:2, and 2:1. The total solids for co-digestion were 8% for all ratios. The results showed that the ratio of 2:1 produced the highest biogas yield (46.7 m 3 /ton of slurry) and 53.2% of methane purity. The pH fluctuated around a range of 5.2 to 7.9 due to different stages of anaerobic digestion as a result of microbe's activity.

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Solid waste management towards the sustainable process is one of the major undertakings of the Malaysia Solid Waste Management Department. Hence, development towards biofuels including biogas production from wastes has been escalating in Malaysia. There have been some major innovations in biogas production, including design and operation of the reactor, the presence of an additive, change in mixing regime, supporting unit, measurement, and monitoring systems, since the technology has developed. The sections mainly included are types of digesters, strategies such as upstream, mainstream, and downstream. In upstream strategies, the hydrothermal pretreatment of anaerobic digestion showed a higher improvement of biogas by an increase of 222 % of methane content. The mainstream strategies showed that co-digestion was the best method to increase the methane yield to 305-445 mL g -1 VS. In downstream system, methane content can be upgraded from 60 to 90 % by applying water scrubber. This paper aims to discuss the recent trends and innovations in biogas production from waste and their pathways in details.