Plasma-Mediated Transformation Kinetics and Stability of Nitrogen Species in Tea Factory Waste

As India’s largest tea-producing region, Assam generates enormous amounts of tea factory waste (TFW), creating significant environmental and waste management challenges due to its high organic and nutrient content. Conventional disposal methods often fail to address pollution risks or recover valuable resources from this abundant agro-industrial by-product. The present study investigates how nonthermal plasma (NTP) processing affects the physiological characteristics and nitrogen compounds in TFW, focusing specifically on the breakdown and build-up of nitrate (N\!O₃⁻) and ammonium (N\!H₄⁺), along with the stability of reactive ions. Over time, observations revealed that the formation of nitrate aligns with pseudo-first-order kinetics, with the formation rate highly contingent on the plasma treatment duration. Plasma treatment of 30 min resulted in the quickest formation, aligning with moderate acidification and controlled ammonium build-up. In contrast, shorter treatment times led to substantial increases, attributed to the reductive conditions and an initial low pH. This study integrates plasma science with waste valorization to facilitate nutrient recovery and sustainable waste management, while reducing environmental risks and advancing circular economy approaches.