Exploring gypsum wallboard waste disposal alternatives

Abstract

Most landfills in South Africa are rapidly running out of airspace. This calls for the implementation of sustainable alternative waste management solutions to move waste, such as gypsum wallboard waste, up the waste management hierarchy. Although the environmental and social impacts associated with the disposal of gypsum wallboard waste in landfills are well understood, and the alternatives to landfill disposal are extensively researched on an international scale, there is limited publicly available research on the use of gypsum wallboard waste in South Africa. This study aimed to explore alternative options to landfill disposal of gypsum wallboard waste within the South African context. This was achieved through evaluating the physico-chemical properties of gypsum wallboard waste, identifying the alternatives to the landfill disposal; and investigating the opportunities and challenges associated with gypsum wallboard waste alternative use. The study employed a mixed-method design, using qualitative and quantitative techniques. The results of the study indicated that gypsum wallboard waste is non-hazardous and is not likely to pose any physical, health or environmental hazards. In addition, the physico-chemical properties of the gypsum wallboard make it suitable for potential alternative uses identified in literature, prompting further investigation of alternatives through field experiments and interviews. The results from field experiments indicated that the presence of the gypsum wallboard waste in composting dampened the temperature of the compost, but the pH, EC and moisture content of the compost remained within the required composting limits. Also, the sodium and the heavy metal concentrations of the compost were reduced suggesting that gypsum wallboard waste is capable of reducing the salinity and toxic levels of heavy metals in compost to below lethal levels. The study also found that up to 20% of gypsum wallboard waste can be added to produce a fertilizer before reducing the concentrations of boron to deficiency levels. Of interest to this study, the gypsum wallboard waste drastically reduced the concentrations of pathogens, and increased the concentrations of calcium and sulphur nutrients in correlation to the quantity of gypsum wallboard added. This suggested that gypsum wallboard waste supplied the essential nutrients required by plants to the compost and has the potential to sterilise the infectious pathogens in compost that are harmful for human and animal consumption. The results from interviews indicated that 78% of composters interviewed were not interested in utilising gypsum wallboard waste in their composting processes - mainly because of its quality and origin. On the other hand, gypsum wallboard manufacturers expressed their interest in utilising recycled gypsum in the manufacturing of new wallboard with the aim of improving company image, achieving environmental targets and earning points from the green building council. To make alternatives such as fertilizer production from wallboard waste more favourable than landfill disposal, measures such as landfilling gate fees and landfill restrictions/bans for the disposal of gypsum wallboard waste are suggested.