Treatment Of Pig Slurry Research Articles

Thermophilic aerobic treatment of pig slurry

This paper presents the results of a laboratory scale experiment in which pig slurry was treated aerobically in a continuously fed, 151 fermenter operating at a temperature of 55°C. The reductions in total solids, COD and BOD 5 are greater than corresponding results at a temperature of 15°C, particularly at short retention times. Nitrogen measurements indicate an increase in true protein levels and very low nitrate production. Results for the decay rates of pathogens show a decline from 10 6 to an indetectable level within 4 h. These results suggest that the process may be suitable as a pretreatment of the waste for recycle in a liquid feeding system. Settling experiments were performed on the treated material demonstrating the possibility of separation. The inhibitory effects of copper on the microbial respiration rate was also investigated.

The destruction of pig helminth ova and larvae in a slurry treatment process.

It was established that a thermophilic system for the treatment of pig slurry at 55 degrees C rapidly killed the free living stages of three common pig parasites. This treatment could be beneficially incorporated in any pig slurry recycling process, whether to land or to animals.

A farm plant for pig slurry treatment

The slurry from about 200 fattening pigs was treated over a period of 56 weeks in a treatment system with separation, high-rate filtration and sludge de-watering stages. The overall output of the system consisted of separated solids (19% of slurry input) and de-watered sludge (52% of slurry input) which were stored on the farm midden and were relatively smell-free and easy to handle. When evaporative losses were low in winter there was some filtrate from the de-watering stage for disposal as liquid effluent. When evaporative losses were high in summer water was added to maintain the plant liquid level. A total of 28,9501 of water were added and 25,1901 of filtrate removed giving a net 37601 water input in addition to an estimated 20,160 1 of rainwater which entered the plant. If rainwater were excluded it is likely that there would be no liquid effluent from the plant even when evaporative losses were lower than those prevailing during the trial period which included the hot dry summer of 1975. There was good agreement between the evaporative losses calculated from the experimental results and those predicted from weather data. About 38% of total N and 77% of NH 4N were lost during treatment but there was no loss of P and K. The sludge was conditioned prior to de-watering with aluminium chlorohydrate or ferric sulphate which was the cheaper at £2·64 pig place per year. Laboratory trials showed that a number of polyelrolytes were ineffective and none was as cheap as ferric sulphate. The complete system was easily operated by farm staff, and apart from the separator, which was a very early prototype machine, was robust and reliable enough for farm conditions.

A mathematical model of a pig slurry treatment system

Mathematical models have been developed of a pig slurry treatment system which includes mechanical separation of the fibre from the raw slurry, treatment of the defibred slurry in a biological filtration tower and then a further separation of sludge. Both the fibre and sludge are handled as stackable solids. Evaporation is considered to take place from the slurry within the pig house, within the filtration tower and from the defibred slurry which is being desludged. The models are suitable for considering both steady and variable inputs of raw slurry and evaporation. This study indicates many of the problems likely to be encountered when designing and operating such a system. In particular it has been shoen that only small reductions in the dry matter content of the raw slurry can result in very large increases in the amount of liquid to be handled.