Hybrid ultrasonic surfactant system for rapid and eco friendly removal of oily sludge from crude oil storage tanks

Crude oil storage tanks are prone to the gradual accumulation of dense, tenacious oily sludge. This sludge consists of heavy hydrocarbon residues, water in oil emulsions, fine particulates and corrosion products that adhere to tank walls and settle in low-lying zones. Over time, the buildup compromises tank integrity, impedes product turnover, and creates a fire hazardous environment. The most widely employed remediation strategy relies on high-energy mechanical agitation, typically scale pump circulation, high-pressure water jets, or rotary scrapers to dislodge the sludge. While effective in fragmenting loose deposits, these methods demand substantial power inputs, generate vigorous turbulence that can aerosolize hazardous hydrocarbons, and often require aggressive solvents or detergents to achieve acceptable removal levels. The resultant occupational exposure risks, elevated energy consumption, and the generation of secondary waste streams render conventional mechanical treatment environmentally and economically burdensome.

This present work introduces a novel cleaning methodology that synergistically couples a low-dose non-ionic surfactant with high-intensity ultrasonication. The surfactant’s amphiphilic architecture markedly reduces interfacial tension, promoting rapid wetting and dispersion of the heavy hydrocarbon matrix. Simultaneously, ultrasonic cavitation produces micro-jets and shock waves that mechanically disintegrate sludge agglomerates at the microscale. Laboratory trials demonstrate removal efficiencies exceeding 90 % within a 2-hour treatment window, substantially higher than those achieved by conventional chemical or mechanical techniques. The process operates at ambient temperature and pressure, minimizing energy consumption and eliminating the need for aggressive solvents or high-velocity mechanical equipment. These results underscore the scalability and environmental compatibility of surfactant-assisted ultrasonication as a superior alternative for routine tank cleaning and remediation, offering rapid, near-complete sludge dissolution with reduced chemical dosage, energy demand and manpower while markedly improved safety for personnel and the surrounding ecosystem.