Towards maximising output from vermireactors fed with cowdung spiked paper waste

Paper waste, spiked with varying proportions of cowdung, was vermicomposted in ‘low-rateʹ and ‘high-rateʹ reactors. The former type of reactors had earthworm populations and feed loading rates similar to ones recommended by previous workers. The ‘high-rateʹ reactors were operated with 12.5 times higher earthworm densities and feed loading rates. All the reactors were studied for six months to assess the vermicast output, survivability, growth and reproduction of the earthworms – hence the sustainability of the reactors – for long-term, continuous operation. The studies revealed the viability of the high-rate vermireactor concept. The high-rate reactors consistently produced over 6.5 times more castings per unit digester volume with no adverse effect on the earthworm population, as reflected by (a) absence of mortality, (b) consistent growth in worm zoomass, and (c) normal rate of reproduction. The studies also revealed that an increase in the cowdung fraction in the feed from 14.3% to 20% (4:1 paper:cowdung blends to 6:1 blends) had little positive impact on the vermicast output or earthworm health. This indicated that spiking of paper feed with 14% cowdung, or perhaps an even smaller fraction, might be adequate to support earthworms in the paper-fed vermireactors.