Occurrence of micro-organic pollutants on phosphorus recovery from urine

Increased population growth and food prices have resulted in more demand for fertilizers, especially phosphorus (P), to be used in agriculture and production of food crops. Phosphorus is one of the important natural resources and will be exhausted in the near future. Nowadays, struvite production is a good method to recover P from urine. However, the natural urines contain high amounts of micro-organic pollutants which may cause health risks. Therefore, in this contribution, we investigated the amount of micro-organic pollutants in struvite from urine. There are various kinds of pharmaceuticals and hormones which are used in the world. Nevertheless, we focused on 10 pharmaceuticals (amoxycillin, carbamazepine, erythromycin, furosemide, atenolol, ibuprofen, norfloxacin, trimethoprim, tetracycline, and acetylsalicylic acid) and one hormone (17β-estradiol) as representatives. The experiments were carried out with synthetic and natural urines. After the production of struvite, the results from synthetic and natural urine samples showed that only tetracycline, erythromycin, and norfloxacin remained in the struvite, and, especially, tetracycline remained in struvite with quite a high amount.     

Predicting struvite formation for phosphorus recovery from human urine using an equilibrium model.

Interest in phosphorus recovery from urine diverted from faeces has been growing recently. Phosphorus in urine can be precipitated out as struvite (MgNH4PO4 x 6H2O) with addition of magnesium salt under alkaline conditions. Struvite formation, however, should be more well understood for its practical application. We predicted the struvite formation with a development of a new equilibrium model. The model considered the formation of eight different kinds of precipitates, including struvite, with effects of ionic strength and temperature. In addition, experiments on struvite formation in urine were conducted for the model validation. The model prediction of struvite formation had good agreement with the experimental results. The optimum pH to form struvite was predicted to be 9.4-9.7. In order to precipitate 99% of phosphate in urine with 1.5 fold Mg concentration to PO4-P, the pH value was necessary to be more than 8.1 based on the model prediction.     

A THEORY OF MONEY AND MARKETPLACES*

This article considers an infinitely repeated economy with divisible fiat money. The economy has many marketplaces that agents choose to visit. In each marketplace, agents are randomly matched to trade goods. There exist a variety of stationary equilibria. In some equilibrium, each good is traded at a single price, whereas in another, every good is traded at two different prices. There is a continuum of such equilibria, which differ from each other in price and welfare levels. However, it is shown that only the efficient single‐price equilibrium is evolutionarily stable.     

Development of an integrated analysis procedure for three-ways layout field surveys data in lakes.

Lake water quality systems are extremely complex and every lake is characterized by many complicated interactions between biological, chemical and physical variables. One of the most important tasks of lake mechanism analysis is to examine the relations among important water quality variables and to describe such complicated relationships quantitatively, simply and practically. Lake Biwa was chosen as a target lake, where a periodic water quality investigation was conducted every month from 1979 at 50 sampling sites. The objective of this study is to establish an application procedure of three-ways layout data and to present a vision including its practical result, expecting that this vision may also provide a direction for further research. The results showed that (1) cluster analysis following the three-ways layout ANOVA method is very effective in presenting water quality variation, (2) correlation analysis of water quality indices in each effect of parameters and their interaction between two items verifies that their relationships in parameters are different due to different mechanisms. (3) An integrated analysis procedure was derived, potentially describing those data in forms which convey their important characteristics and reveal their significant relationship. The same approach of this analysis procedure could be possibly applied for other water quality indices in other lakes.     

Who explores further? Evidence on R&D outsourcing from the survey of research and development

Building off the resource‐based view and the knowledge‐based view, our study aims to examine determinants of firms’ R&D outsourcing, using annually‐conducted firm‐level survey data of Japanese R&D companies from 1984–2012. This survey allows us to measure strategic R&D outsourcing, isolated from those more for cost‐reducing, such as prototyping, testing and inspecting. The results corroborate the argument of complementarity in scale between internal R&D and R&D outsourcing. We also find that firms employing more doctorate holders and diversifying in knowledge spaces tend to make more use of R&D outsourcing. This study sheds light on firms’ absorptive capacity, associated both with higher‐order R&D human capital and diversified knowledge spaces, as determinants of R&D outsourcing.