Chapter 17 Experimental Investigation into the Applicability of Nanoparticles in Purification of Sewage Water Through Usage of Solar Energy Virender Ohri and Vikrant Khullar Abstract In recent years, solar energy driven water desalination/purification systems have been extensively researched with the objective of improving the distillate yield. In these conventional solar driven systems, solar energy heats the water indirectly i.e. in these systems the solar energy is transferred to the water through conduction, resulting in evaporation and hence purification of the water. The present work explores the idea of adding nanoparticles into the wastewater so that solar energy is transferred to water volumetrically, which considerably improves the evaporation rate. Amorphous carbon nanoparticles have been used owing to their high solar weighted absorptivity values. Careful experiments have been carried out to quantify the effect of nanoparticles on the evaporation rate. It was found that optimum level of nanoparticles addition could actually enhance the evaporation rates of the sewage water by *15%. Furthermore, total dissolved solids (TDS) and pH measurements showed considerable improve- ments, the values being in the range to qualify for drinkable water. Keywords Solar energy Á Nanoparticles Á Evaporation Á Condensation Sewage water Nomenclature D Mean particle diameter of nanoparticles [nm] f v Particle volume fraction inside base fluid I k Spectral intensity of sunlight [Wm -2 μm -1 ] K Radiative coef ficients [m -1 ] m Normalized refractive index, m ¼ n þ ij n Index of refraction y Distance from the free surface [m] V. Ohri Á V. Khullar (&) Mechanical Engineering Department, Thapar Institute of Engineering and Technology, Patiala 147004, Punjab, India e-mail: vikrant.khullar@thapar.edu © Springer Nature Singapore Pte Ltd. 2019 H. Tyagi et al. (eds.), Advances in Solar Energy Research, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-13-3302-6_17 537