A Biosolids Composting Challenge: Meeting Demand for a Peat‐Free Horticultural‐Grade Product

Abstract

In 1996, Thames Water launched a range of peat‐free compost products based on biosolids. In order to keep up with demand and to maintain the high standards of product quality, the company has investigated higher‐rate composting processes and optimisation of the maturation stage. Agitated‐bay composting systems are the preferred in‐vessel technology for large sludge treatment centres using woodchip as a bulking agent. These automated systems (i) accelerate the composting process, (ii) maximise throughput on a smaller footprint, and (iii) achieve better control of odour emissions. A maturation trial with composted material from the US Filter agitated‐bay system confirmed that a horticultural‐grade product could be attained. Small‐scale maturation trials showed that seeding with mature green waste compost can accelerate nitrification to such a rate that near zero levels of ammonia can be achieved after one month of maturation.

Biosolids and Sludge Management

“…The effects of media composition on plant growth and development varied with each species tested. These researchers, however, observed some impairment in plant development using only compost, but found that regardless of media composition, plants were of high visual color and acceptable quality Bowman and Durham (2002). reported on a range of peat-free compost products based on biosolids launched by the Thames Water in 1996.…”