Effects of Value-added Biochar-Modified Substrate made from Sludge on Green Roof Plants - A Case Study of Sedum lineare

Urban green roofs are increasingly valued for their ecological benefits, yet their performance is highly dependent on substrate quality. The research aimed to evaluate the effects of three waste derived substrate— biochar (BC), modified biochar (MBC), and sludge biochar (SBC)— on the growth of Sedum lineare. SBC was produced by mixing aluminum-sludge and acid-modified corn cob biochar in a 1:1 mass ratio, followed by pelletizing, drying, and pyrolysis at 400 ° C. A 120-day pot experiment under controlled conditions assessed morphological, physiological, and carbon fixation parameters at 30-day intervals. Results showed that SBC significantly enhanced relative water content (+14.15%), plant biomass (+25– 40%), and carbon sequestration (+40.05%) compared to the control. The improved matrix also reduced carbon loss by 66% due to its stable structure and high organic carbon retention. The novelty of this study lies in integrating waste-derived sludge biochar and acid treatment to form a low-cost, high-performance substrate, offering a sustainable solution for urban ecosystem design. This research contributes a novel waste-derived substrate formulation that simultaneously promotes plant growth and enhances environmental benefits.