Utilizing biochar from dairy sludge for effective dairy wastewater treatment: a sustainable approach

This study explores the potential of dairy processing sludge (DPS) as a resource for producing biochar to treat dairy wastewater. DPS contains hazardous pollutants such as antibiotics, hormones, pesticides, disinfectants, and microplastics, posing environmental risks. Through pyrolysis at 250°C–350°C, DPS was converted into biochar using an innovative, low-cost, small-scale system called BioCharan, which utilises a modified mustard oil tin for on-site production. The resulting biochar displayed favourable characteristics, including 40.067% carbon, 5.354% hydrogen, and 2.743% nitrogen content, confirmed through Fourier-transform infrared and X-ray diffraction analysis. A filtration system combining this biochar with river sand was developed and tested for its pollutant removal efficiency. The system effectively removed total suspended solids (83.71%), oil and grease (66.82%), chemical oxygen demand (42.86%), biochemical oxygen demand (31.55%), sulphate (30.77%), phosphate (26.67%), nitrate (25%), total Kjeldahl nitrogen (23.53%), total dissolved solids (11.72%), and fluoride (1.72%), while also improving pH from 6.30 to 6.74. Key parameters like porosity and surface area supported the biochar’s strong adsorptive capabilities. This research highlights a sustainable approach by converting sludge waste into an effective treatment medium, offering an eco-friendly solution for both waste disposal and water purification, thus presenting a circular strategy in dairy wastewater management.