Cost-Effective Leachate Treatment and Resource Recovery in Hazardous Waste Landfills through Pipe Freeze Crystallization.

Abstract

This study aimed to develop a practical, economically viable solution for treating hazardous landfill leachate using Pipe Freeze Crystallization (PFC) technology. The objective was to concentrate and solidify leachate from an effluent treatment plant processing approximately 8750 m³ annually, achieving resource recovery and environmental compliance. A 300 L h^-1 cooling demonstration plant was designed and implemented, incorporating a chiller, a secondary refrigerant mixture (40% ethylene glycol and 60% water), a clarifier, a reactor, and pumps. Μodelling with OLI software estimated recovery rates for salt and ice, providing a basis for operational adjustments. Leachate samples (2000 L) and concentrate (1000 L) were processed to evaluate the plant's performance in recovering clean water and Na₂SO₄. Experimental results confirmed the model predictions, with 302 L of concentrate yielding 102.9 kg of Na₂SO₄ over 6 h and 273 L of leachate producing 118.7 kg of high-purity ice over 5.5 h. The energy consumption was measured at 171 kWh t^-1 of ice, aligning with theoretical predictions for a coefficient of performance of 1. These results validate the efficiency and feasibility of PFC in resource recovery. This study highlights the importance of PFC as a low-cost, energy-efficient technology for hazardous leachate treatment. Its scalability and ability to recover valuable resources such as Na₂SO₄ and clean water present a sustainable alternative to conventional methods, contributing to zero-waste management goals in waste treatment practices.

Supplementary information: The online version contains supplementary material available at 10.1007/s40710-025-00757-3.