Techno-economic assessment at full scale of a biogas refinery plant receiving nitrogen rich feedstock and producing renewable energy and biobased fertilisers.

Anaerobic digestion of nitrogen (N) rich substrates might be hindered when ammonia (NH3) formation reaches toxic levels for methanogenic microorganisms. One possible strategy to avoid inhibiting conditions is the removal of NH3 from digestate by stripping and scrubbing technology and by recirculating N depleted digestate back to the digester. This study aimed to i) monitor the performance (mass and energy balances) of a full scale digestate processing cascade that includes an innovative vacuum side stream NH3stripping and scrubbing system, ii) assess the production cost of ammonium sulphate (AS) solution and iii) evaluate its fertiliser quality. The use of gypsum to recover NH3 in the scrubbing unit, instead of the more common sulphuric acid, results in the generation of AS and a fertilising liming substrate. Mass and nutrient balances indicated that 57% and 7.5% of ammonium N contained in digestate was recovered in the form of a 22% AS and liming substrate, respectively. The energy balance showed that about 3.8 kWhel and 59 kWhth were necessary to recover 1 kg of N in the form of AS. Furthermore, the production cost of AS, including both capital and operational costs, resulted to be 5.8 € t-1 of digestate processed. According to the fertiliser quality assessment, this technology allows for the recovery of NH3in the form of salt solutions that can be utilised as a substitute for synthetic mineral nitrogen fertilisers.

Production and performance of bio-based mineral fertilizers from agricultural waste using ammonia (stripping-)scrubbing technology.

Development and optimization of nutrient recovery technologies for agricultural waste is on the rise. The full scale adoption of these technologies is however hindered by complex legal aspects that result from lack of science-based knowledge on characterization and fertilizer performance of recovered end-products. Ammonium sulfate (AS) and ammonium nitrate (AN), end-products of (stripping-)scrubbing technology, are currently listed by the European Commission as high priority products with the potential of replacing synthetic N fertilizers. The legal acceptance of AS and AN will be highly dependent on critical mass of scientific evidence. This study describes four different (stripping-)scrubbing pathways to recover ammonia with an aim to (i) assess product characteristics of ammonium nitrate (AN) and ammonium sulfate (AS) produced from different installations, (ii) evaluate fertilizer performance of recovered end-products in greenhouse (Lactuca sativa L.) and full field (Zea mays L.) scale settings and (iii) compare the observed performances with other published studies. Results have indicated that the recovered products might have a different legal status, as either mineral N fertilizer or yet as animal manure, depending on the used (stripping-)scrubbing process pathway. Nevertheless, no significant differences in respect to product characterization and fertilizer performance of AN and AS have been identified in this study as compared to the conventional use of synthetic N fertilizers. This indicates that recovered AS and AN are valuable N sources and therefore might be used as N fertilizers in crop cultivation.

Subclinical hypothyroidism and myocardial function in obese children.

BACKGROUND AND AIMS: Pediatric obesity is an important health problem representing a major public health concern worldwide in the last decades. An isolated elevation of Thyroid Stimulating Hormone (TSH) with normal levels of thyroid hormones is frequently found in obese children. It has been named Isolated Hyperthyreotropinemia or Subclinical Hypothyroidism (SCH) and may be considered a consequence of obesity. Evidence exists that SCH is related to impairment of both systolic and diastolic myocardial function in the adult population. The aim of our study is to establish if obesity-related SCH influences myocardial function in children. METHODS AND RESULTS: We examined 34 obese children and adolescents with SCH and 60 obese children with normal TSH levels who underwent Doppler echocardiographic to evaluate myocardial function. Global systolic function as assessed by Ejection Fraction (EF) was comparable between groups, however Right Ventricle pressure global systolic function and pressure were significantly reduced in SCH group. Mitral annulus peak systolic (MAPSE) excursion lateral and MAPSE septum resulted significantly reduced in SCH group. Tissue Doppler imaging peak systolic motion (TDI-S) was reduced in SCH group. Diastolic function also showed significant modifications in SCH group. CONCLUSION: These results suggest possible involvement of cardiac function in obese children with SCH resulting in both abnormal diastolic function and reduced longitudinal systolic function. This new insight into cardiovascular consequences of obesity-related SCH in children could influence clinical approach to such patients by pediatric endocrinologists.

Variations of retinol binding protein 4 levels are not associated with changes in insulin resistance during puberty.

Retinol binding protein 4 (RBP4) is an adipokine involved in the pathogenesis of insulin resistance in obese adults and children. Since insulin resistance occurs during puberty, independently of adiposity, a role for RBP4 in the onset of this phenomenon may be hypothesized. In order to verify our hypothesis, we studied 90 subjects (45 obese and 45 lean controls). A complete physical examination was assessed, the z-score body mass index (BMI) was calculated, fat mass was assessed by bioelectric impedance analysis, and pubertal stage was assessed according to Tanner. Serum insulin and serum RBP4 levels were assayed. Obese and lean children differed for z-score BMI, fat mass, homeostasis model assessment of insulin resistance (HOMA-IR) and RBP4 levels. z-score BMI and HOMA-IR showed a direct correlation with RBP4 in the total population. When the subjects were divided in lean and obese, this correlation was evident only in obese (r2: 0.2; p=0.009 and r2: 0.2; p=0.01), but not in lean subjects (r2: 0.09; p=0.1 and r2: 0.03; p=0.4). Both in obese and lean HOMA-IR values were higher in pubertal subjects than in pre-pubertal (p<0.001), while serum RBP4 levels were similar in pubertal and in pre-pubertal subjects (>0.1). We conclude that RBP4 is correlated with adiposity and insulin resistance in obese children, but it is not involved in the insulin resistance occurring during puberty.

Growth and bacteriocin production by Enterococcus faecium DPC1146 in batch and continuous culture.

Production of the bacteriocin enterocin 1146 (E1146) by Enterococcus faecium DPC1146 was studied in batch and continuous fermentation. Growth was strongly inhibited by lactic acid. In batch fermentations maximum E1146 activity (2.8 MBU L-1) was obtained in 9 h with 20 g L-1 glucose. Increase in initial glucose concentration did not lead to a proportional increase in E1146 activity. A simple linear model was found to be adequate to explain the relationship between specific bacteriocin production rate and specific growth rate in batch fermentations with initial glucose concentration higher than 20 g L-1. Maximum bacteriocin activity (2.9-3.2 MBU L-1) was obtained in continuous fermentations at dilution rates between 0.12 and 0.17 h-1 and specific bacteriocin production rate increased linearly with dilution rate.