Mohamad K. Khawaja

Microbial fuel cells (MFCs) provide a membrane-based bioelectrochemical route for simultaneous wastewater treatment and electricity generation. This study investigates the effect of aeration and mixing on the performance of dual-chamber microbial fuel cells (DCMFCs) operated outdoors using sugar-mix substrates. Five DCMFC configurations were evaluated over 40 days, including baseline operation and individual or combined aeration and mixing strategies. Voltage and current were recorded every 15 min, while solar insolation and ambient temperature were monitored to assess environmental effects. Chemical oxygen demand (COD) was measured to evaluate wastewater treatment performance. The configuration with continuous aeration and mixing achieved the best performance, reaching a maximum voltage of 563.2 mV and a peak power output of 250.58 µW. Compared with baseline Cell 1, Cell 5 showed a 72.5% higher Week 6 maximum power density. The final COD concentration in Cell 5 was 12.4% lower than that measured in baseline Cell 1; this represents an endpoint difference rather than a reactor-specific COD removal efficiency. Exploratory correlation analysis showed configuration-dependent associations between electrical output and ambient conditions but did not identify a consistent positive relationship between solar insolation and power generation. These results demonstrate that combined aeration and mixing can improve DCMFC performance under realistic outdoor conditions and support the development of scalable, low-resource systems for decentralized bioenergy generation and wastewater treatment.

Seasonal thermal energy storage (STES) can be utilized to cover a portion or meet the whole space and water heat demands in residential and commercial buildings. With the scarcity of fuel resources, scientists have become aware of the importance of the utilization of thermal energy. An STES system can be charged using solar collectors to heat a storage medium when solar radiation is available. Solar irradiance is seasonal so this type of system can compensate for the shortage of energy in the winter by storing surplus solar energy in the summer. This study offers an innovative design of an STES system that takes advantage of the backfill space in a building’s underground foundation to install the thermal storage medium on the excavated surface among the support pillars’ base. To study the feasibility and the feasibility of such STES system, the design was simulated using the TRNSYS® tool where the STES medium was charged by a solar thermal system. The chosen building type was a four-story hotel located in three cities each with its unique climate: Potsdam (Germany), Zarqa (Jordan), and Doha (Qatar). The results showed the coverage rate of the building’s annual heat demand was 56%, 82%, and 84%, and the payback periods were 3.4, 4.4, and 29 years for Potsdam, Zarqa, and Doha, respectively. Zarqa is the most efficient and feasible for STES compared to the other two cities.

Essential energy needs are not always met in poor and rural areas of developing counties; therefore, natural energy sources are necessary to mitigate this problem. Rural areas inhabitants utilize methane as a replacement for cooking gas to reduce their gas bill. Methane gas can be produced from a biogas digester; however, operating a large digester in a densely populated village in Jordan can be challenging due to inefficient village waste management systems. On the other hand, using a small-scale portable biogas digester to generate biogas could overcome these problems. In this work, three biogas digester feedstocks for a small portable biogas digester from natural sources available in Jordanian villages such as human and animal waste were designed and evaluated. The three feedstocks are food waste, human waste, and a mixture of human and food waste. The parameters tested were the digester size and the biogas production. The results showed that the best digester for portable application was that which digested a mixture of human and food waste; for a five-member family, this type of digester provided 115% of the family’s cooking gas requirements with a digester volume of 0.54 m³. This design, while applicable for a typical rural Jordanian family, can also be utilized globally.