Search

A sufficiently high composting temperature should inactivate many common pathogens likely to be present in solid animal waste. Monitoring core temperatures inside compost heaps is not straightforward, which means that heaps are not generally monitored. An alternative is to monitor surface temperatures and use those data to infer core temperatures, and thus whether pathogen inactivation has occurred. This paper describes two methods (thermal imaging and thermocouples) for the measurement of surface temperature, and a modelling approach using time series analysis to predict the temperatures obtained in the core of aerated heaps of composting pig farmyard manure (FYM) from surface temperature data. The model was able to predict core temperatures in the heap quite closely for a period of time for well insulated parts of the heap, although predictions were further from observed values close to the surface of the heap and the aeration pipe.

The options for abating ammonia emissions from livestock buildings and waste stores under UK conditions have been assessed. There is increasing interest in reducing such emissions, which contribute to long-range atmospheric pollution problems, and which, via subsequent deposition, can also harm sensitive ecosystems. A literature review was first carried out, and a “brainstorm” idea-generating session was held, together leading to lists of feasible abatement approaches: one for each of a range of types of livestock buildings and waste stores. A ranking exercise was then conducted. A set of aspects of each application of each feasible abatement approach was drawn up: the aspects considered included not only capital costs and running costs but also such others as animal welfare, stage of development and knock-on effects. Each aspect of each application of each approach was given a ranking of between 1 (very poor) and 5 (very good). When the aspects of “potential abatement” and “achievable abatement now”, as well as either “capital costs” or “animal welfare”, were weighted by a factor of 5, the “best bet” abatement approaches for livestock buildings were identified as (a) dietary manipulation (for all types), (b) raising the C/N ratio by generous use of bedding (for any buildings based on solid manure), (c) exhaust air cleaning, especially by bioscrubbers (for force-ventilated pig and poultry buildings), (d) oil layers or (e) fixing with acid (for slurry-based piggeries) and (f) drying by ventilation of muck (for any poultry building). For waste stores, the “best bet” abatement approaches were identified as (g) replacing storage with industrial scale processing or (h) with land filling (niche solutions only), (i) dietary manipulation, (j) fixing with acid (slurries only), (k) increasing the surface's resistance to ammonia volatilisation (by crusts for cattle slurry, but by floating granules for pig slurry), (l) minimising surface area by heap shape (solid manures), and (m) cover sheets (solid manures). For stored poultry manure, the low moisture content allowed good showings by the additional options of (n) drying, and, in the case of poultry manure with litter in certain parts of the UK, (p) sale for combustion in a Non-Fossil Fuel Obligation (NOFFO) power station, the electricity from which commands a higher price than that from a conventional power station. A closer look at the economic consequences of different abatement approaches was taken by means of a mathematical model: this work is reported in a companion paper.