Sewage sludge drying by energy recovery from OFMSW composting: Preliminary feasibility evaluation

In this paper an original energy recovery method from composting is analyzed. The integrated system exploits the heat available from the aerobic biochemical process in order to support the drying of sewage sludge, using a specific solar greenhouse. The aim is to tackle the problem of organic waste treatment, with specific regard to food waste. This is done by optimizing the energy consumption of the aerobic process of composting, using the heat produced to solve a second important waste management problem such as the sewage waste treatment. Energy and mass balances are presented in a preliminary feasibility study. Referring to a composting plant with a capacity of 15,000 t/y of food waste, the estimation of the power from recovered heat for the entire plant resulted about 42 kW. The results demonstrated that the energy recoverable can cover part of the heat necessary for the treatment of sludge generated by the population served by the composting plant (in terms of food waste and green waste collection). The addition of a renewable source such as solar energy could cover the residual energy demand. The approach is presented in detail in order for it to be replicated in other case studies or at full scale applications.     

A comparison of amniotic fluid alpha-fetoprotein and acetylcholinesterase in the prenatal diagnosis of open neural tube defects and anterior abdominal wall defects

Amniotic fluid samples received for routine prenatal diagnosis of open neural tube defects were used for a study to compare amniotic fluid acetylcholinesterase (AChE) determination using a monoclonal antibody (4F19) enzyme antigen immunoassay and amniotic fluid alpha-fetoprotein (AFP) measurement as diagnostic tests for open neural tube defects. The study was based on 9964 women with singleton pregnancies and known outcome (including 6 with anencephaly and 18 with open spina bifida) having an amniocentesis at 14–23 weeks of gestation. The AChE immunoassay yielded detection rates for anencephaly of 100 per cent (95 per cent confidence interval (CI) 54·07–100 per cent), for open spina bifida of 100 per cent (95 per cent CI 81·47–100 per cent), for anterior abdominal wall defects of 20 per cent (95 per cent CI 0-51-71-64 per cent), and a false-positive rate of 0·22 percent (95 per cent CI 0·14–0·34 per cent) excluding anencephaly, open spina bifida, and anterior abdominal wall defects. For similar detection rates the false-positive rate of the AFP test was significantly higher, 0·74 per cent (95 per cent CI 0·58–0·94 per cent). On the basis of these findings, it is recommended that the technically simple AChE immunoassay should be used on all samples; the AFP test should only be used on the 0·5 per cent of the samples with concentrations of AChE activity ⩾ 8·5 nkat/1 for clear samples and blood-stained samples becoming clear after centrifugation, and ⩾ 25·0 nkat/1 for blood-stained samples that are discoloured after centrifugation; an AFP cut-off level of 2·0 MOM is recommended for this policy. Thereby, the detection rates for anencephaly, open spina bifida, and anterior abdominal wall defects would be 100, 100, and 20 per cent, respectively (95 per cent CIs 54·07–100, 81·47–100, and 0·51–71·64 per cent, respectively), and the false-positive rate would be 0·08 per cent (95 per cent CI 0·03–0·16 per cent) (excluding anencephaly, open spina bifida, and anterior abdominal wall defects).     

Analyzing the carbon footprint from public services provided by counties

In this paper we investigate the Carbon Footprint (CF) resulting from the activities of the county of Sogn og Fjordane (SFK). An Environmentally Expanded Input-Output model is applied to develop a consumption-based Greenhouse Gas (GHG) inventory for this purpose. The model has previously been used for the assessment of municipal CFs, and is in this paper further developed for the purpose of assessing county CFs. Results show that a large fraction of the CF is caused by the purchase of services from private actors, especially the purchase of transportation services, of which a steady increase from the year 2002–2008, is found. In the same period of time, the CF resulting from the operation of county vehicles has been reduced to only 1/6. This outsourcing regarding the provision of services is found in several departments of the county municipality. It indicates a necessary shift in local mitigation strategies, as more focus needs to be on the environmental performance of suppliers. One important finding in the SFK case is the potential of introducing environmental requirements in tenders on providing transportation services. Another is to make environmental requirements to the companies receiving financial support from the county administration.