Biogas is generated during the anaerobic digestion of wastewater or biodegradable solid wastes and has been recently considered an important energy vector to achieve the energy transition towards the use of clean energy to limit global warming and meet the long-term decarbonization goals of the world economy. Biogas is mainly composed of methane (40–75%), and other compounds considered as contaminants such as carbon dioxide (15–60%), hydrogen sulphide (0.005–2%), water (3–10%), oxygen (0–1%) and nitrogen (0–2%), which significantly reduce its heating value and/or generate corrosion in engines. Thereby, biogas must be upgraded to biomethane in compliance with international standards (methane ≥ 90%, carbon dioxide ≤ 2–4% and oxygen ≤ 1%), to be marketed as natural gas and ensure its techno-economic viability. In this sense, photosynthetic biogas purification using microalgal-bacterial consortium has positioned as a promising technology due to its environmental benefits and low operation costs, especially when integrated with digestate treatment since nutrients, such as nitrogen and phosphorous, can be recovered as biofertilizers and biostimulants. However, the low aqueous CO2 solubility and limited microalgae productivity in the photobioreactors are the major drawbacks of this biotechnological platform since they entail the requirement of extensive areas for CO2 uptake by microalgae, hindering its application on an industrial scale. Recently, the use of nanoparticles during photosynthetic biogas upgrading has become an attractive strategy to significantly boost process performance based on their ability to improve CO2 reduction and nutrient assimilation by microalgae. This chapter reviews the state of the art of the different methods applied for biogas purification to date. Special interest is devoted to providing a detailed description of the fundamentals, recent progresses and research results on the photosynthetic biogas purification method combined with nutrient valorisation from digestates. Finally, the evaluation of the impact of nanoparticles on the yield of photosynthetic biogas purification is discussed.