Nitrogen fertiliser value of bioacidified slurry.

Bioacidification of animal slurry has proven to be a good alternative to traditional acidification with sulfuric acid for reducing ammonia emissions. However, the fertiliser value of the bioacidified slurry is yet to be determined before a whole-system assessment can be made. The N fertiliser value of pig slurry either untreated or bioacidified with glucose and/or fermented brown juice (BJ) was investigated in a pot experiment with maize (Zea mays L.) grown in a greenhouse. The slurry treatments were either pre-acidified with sulfuric acid to pH 6.5 or 5.5 before bioacidification, or bioacidified without pre-acidification. Plant growth was good in all treatments, but the bioacidified treatments showed a lower mineral fertiliser equivalence (MFE) value than the non-bioacidified treatments. Average MFE values were 71 %, 62 %, 59 % and 41 % for the non-bioacidified (noC), glucose (glu), glucose and brown juice (glu + BJ20) and brown juice (BJ50) treatments respectively. This reduction was most likely caused by immobilisation of N due to the addition of easily available C from the substrates. The fertiliser value was not affected by the pH, C/N ratio and C content of the treatments, while a positive correlation was found with NH4 + -N content. Pre-acidification positively affected MFE, probably due to higher nutrient availability. Further studies on the effect of different inclusion rates of substrates for bioacidification and the effect of application method on the fertiliser value, as well as studies under field conditions, are needed before recommendations can be made about bioacidification as an alternative to traditional acidification.

Animal Slurry Acidification Affects Particle Size Distribution and Improves Separation Efficiency.

Solid-liquid separation is performed to improve slurry management, and acidification of the slurry is used to reduce ammonia emissions. Acidification is known to affect slurry characteristics, and we hypothesized that it may affect mechanical separation. Our objective in this study was to assess the effects of slurry acidification on particle size distribution and separation efficiency. Two types of slurry, aged pig and fresh dairy, and two different acidification additives, sulfuric acid and aluminum sulfate (alum), were studied. We found that acidification with sulfuric acid promoted phosphorus (P) solubilization for both slurries, but no change was observed with alum. More ammonium was found in the acidified dairy slurry compared with raw dairy slurry, but no difference was found in aged pig slurry. Acidification before separation increased the proportion of the solid fraction in the slurries, and the effect was significantly higher with alum. When alum was used to acidify the slurries, the proportion of particles larger than 100 µm increased significantly, as did the P concentration in this particle size range. The efficiency of P separation increased markedly in both slurries when alum was used, with the removal to the solid fraction of the dairy slurry being almost complete (90%). Because the priority in mechanical separation is to increase the P content in the solid fraction, the use of alum before centrifugation may be the most suitable option for enhancing its nutrient content. We conclude that separation efficiency and particle size distribution are significantly affected by acidification, but the extent of the effects depends on slurry type and on the type of additive used for acidification.

Efficacy of platelet-rich plasma applied to post-extraction retained lower third molar alveoli. A systematic review.

UNLABELLED: Dental retentions have a high prevalence among the general population and their removal can involve multiple complications. The use of platelet rich plasma has been proposed in an attempt to avoid these complications, as it contains high growth factors and stimulates diverse biological functions that facilitate the healing of soft and hard tissues. OBJECTIVES: To evaluate the available scientific evidence related to the application of platelet-rich plasma in the post-extraction alveoli of a retained lower third molars. MATERIAL AND METHODS: A systematic review of published literature registered in the Medline, EMBASE, Cochrane and NIH databases. The following categories were included: human randomized clinical studies. Key search words were: platelet rich plasma; platelet rich plasma and oral surgery; platelet rich in growth factors and third molar. RESULTS: Of 101 potentially valid articles, seven were selected, of which four were rejected as they failed to meet quality criteria. Three studies fulfilled all selection and quality criteria: Ogundipe et al.; Rutkowski et al.; Haraji et al. The studies all measured osteoblast activity by means of sintigraphy, and also registered pain, bleeding, inflammation, temperature, numbness as perceived by the patients, radiological bone density and the incidence of alveolar osteitis. CONCLUSIONS: Scientific evidence for the use of PRP in retained third molar surgery is poor. For this reason randomized clinical trials are needed before recommendations for the clinical application of PRP can be made.