The article presents a novel solution based on dairy wastewater sorption on a biochar substrate obtained through thermal decomposition of Chlorella sp. algae biomass. The algal biomass obtained in the culture medium containing wastewater from dairy production was separated from the culture medium through sedimentation and centrifugation and then freeze-dried. After freeze-drying, the dry biomass was pyrolysed at 600 °C in a CO ₂ atmosphere.The EDS analysis showed that the oxygen-tocarbon (O/C) and nitrogen-to-carbon (N/C) ratios in the obtained material averaged 0.24 and 0.54 respectively. The arrangement and structure of the obtained biochar was evaluated using Raman spectroscopy. The observed spectra revealed the presence of D bands located at 1346–1354 cm ^-1 and corresponding to disordered carbon structures, as well as G bands located at 1585–1594 cm ^-1 and corresponding to tensile vibrations. The D/G intensity ratio was determined at 0.28. The next phase of the research involved sorption of dairy wastewater from cleaning processes containing 1 g of the obtained biochar using solid phase extraction. The study results confirmed high sorption efficiency of the obtained algal biochar. Turbidity was reduced by 93%, suspension by 88%, sulphates by 61%, chlorides by 80%, and organic carbon by 17%. The research confirmed the possibility of using wastewater from dairy production as a natural culture medium for Chlorella sp. algae cultivation to manufacture valuable biochar, which could be used as a sorption bed in the treatment of dairy wastewater from cleaning processes.