Phosphorus is an irreplaceable and depletable element. Furthermore, it has an almost one-way circulation on earth, so it is necessary to close the phosphorus cycle loop. Phosphorus could be recovered as struvite, whic...Phosphorus is an irreplaceable and depletable element. Furthermore, it has an almost one-way circulation on earth, so it is necessary to close the phosphorus cycle loop. Phosphorus could be recovered as struvite, which is a good slow-released fertilizer for agriculture. The supernatant of anaerobic digestion used to treat sludge from wastewater treatment plant is one main source from which phosphorus can be recovered. Studies have proven that phosphorus recovery from digester supematant is a feasible choice to preserve phosphorus rock technically and economically. A modified ＂PHOSNIX＂ P-recovery process was applied under the operating conditions of a 9.0 pH value and a 1.8 mg： P ratio with the influent of the centrate coming from the sludge centrifuge of the Songjiang Wastewater Treatment Plant in Shanghai. More than 80% influent phosphorus was recovered as struvite. Crystal products with good purity and low heavy metal content were gained. The largest crystal had a length of up to 0.26 mm. It was found in our study that the reaction time did not play an important role in crystal growth. Therefore, the optimization of the reaction condition for crystal growth should be examined in future study.展开更多
The hygienic performance of simple storage and biological treatment of manure was evaluated using effluents collected from 44 hog farms across Brittany, France. Analyses were carried out on raw manure, on the sludge s...The hygienic performance of simple storage and biological treatment of manure was evaluated using effluents collected from 44 hog farms across Brittany, France. Analyses were carried out on raw manure, on the sludge stored after biological treatment and on the liquid phase stored in a lagoon after sludge settling or sludge dewatering. The effect of the treatments was evaluated on E. coli, enterococci, Clostridium perfringens, Salmonella and Listeria monocytogenes. Sequential feeding of manure maintained a high level of enteric bacteria in storage tanks regardless the duration of storage, and biological treatment only slightly reduced the concentration of enteric bacteria （average reduction in raw manure and sludge 〈 2.2 log10）. Salmonella and L. monocytogenes were identified in raw manure （50% and 18.2% of samples, respectively）, in sludge （14.8% and 11.1%）, and in lagoons （8.0% and 24%）, suggesting that there is still a sanitary risk after biological treatment of manure. Salmonella Derby and L. monocytogenes serotype 4b each accounted for 50% of the serotypes identified in the samples. There was no correlation between the presence of the two pathogenic bacteria and the size of the herd or the duration of manure storage. However, environmental conditions in the lagoons appeared to favor the presence ofL. monocytogenes and hence a risk of disseminating this pathogen in the environment.展开更多
文摘Phosphorus is an irreplaceable and depletable element. Furthermore, it has an almost one-way circulation on earth, so it is necessary to close the phosphorus cycle loop. Phosphorus could be recovered as struvite, which is a good slow-released fertilizer for agriculture. The supernatant of anaerobic digestion used to treat sludge from wastewater treatment plant is one main source from which phosphorus can be recovered. Studies have proven that phosphorus recovery from digester supematant is a feasible choice to preserve phosphorus rock technically and economically. A modified ＂PHOSNIX＂ P-recovery process was applied under the operating conditions of a 9.0 pH value and a 1.8 mg： P ratio with the influent of the centrate coming from the sludge centrifuge of the Songjiang Wastewater Treatment Plant in Shanghai. More than 80% influent phosphorus was recovered as struvite. Crystal products with good purity and low heavy metal content were gained. The largest crystal had a length of up to 0.26 mm. It was found in our study that the reaction time did not play an important role in crystal growth. Therefore, the optimization of the reaction condition for crystal growth should be examined in future study.
文摘The hygienic performance of simple storage and biological treatment of manure was evaluated using effluents collected from 44 hog farms across Brittany, France. Analyses were carried out on raw manure, on the sludge stored after biological treatment and on the liquid phase stored in a lagoon after sludge settling or sludge dewatering. The effect of the treatments was evaluated on E. coli, enterococci, Clostridium perfringens, Salmonella and Listeria monocytogenes. Sequential feeding of manure maintained a high level of enteric bacteria in storage tanks regardless the duration of storage, and biological treatment only slightly reduced the concentration of enteric bacteria （average reduction in raw manure and sludge 〈 2.2 log10）. Salmonella and L. monocytogenes were identified in raw manure （50% and 18.2% of samples, respectively）, in sludge （14.8% and 11.1%）, and in lagoons （8.0% and 24%）, suggesting that there is still a sanitary risk after biological treatment of manure. Salmonella Derby and L. monocytogenes serotype 4b each accounted for 50% of the serotypes identified in the samples. There was no correlation between the presence of the two pathogenic bacteria and the size of the herd or the duration of manure storage. However, environmental conditions in the lagoons appeared to favor the presence ofL. monocytogenes and hence a risk of disseminating this pathogen in the environment.
