Reducing nitrogen loss and salinity during 'struvite' food waste composting by zeolite amendment

Struvite formation during composting through supplementation of Mg and P salts conserved nitrogen but in the same time increased the electrical conductivity (EC) of the compost limiting its application. Therefore the present study aimed at utilizing zeolite to control the EC under 'struvite' composting of food waste. Zeolite at 5% and 10% (dry weight basis) was supplemented to the composting mass receiving Mg and P salts and compared with treatment with Mg and P salts only and the control without any amendment. Addition of Mg and P salts effectively buffered the pH to ~8.0 but also increased the EC of the compost to 6.45. mS/cm. Co-amendment with 10% zeolite effectively reduced the EC down to 2.82. mS/cm and improved compost maturity. It also increased the adsorption of ammonium ions reducing ammonia loss to 18% resulting in higher total nitrogen content in the final compost.