This study has been prepared within the OPHI theme on multidimensional measurement.

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Conventional wastewater analysis based on on-site sampling holds a limitation of accuracy because of fluctuation of influent composition in time and its corruptible nature in organics. To cope with the problem, this study aimed at developing an alternative method using on-site lab-scale activated sludge reactors, where a set of mean influent material concentrations was calculated from the analysis of activated sludge constituents of which fluctuation was damped due to long sludge retention time. Focusing on the activated sludge collected from the reactor having a primary settling tank, the soluble biodegradable material concentrations in the influent were calculated using IWA Activated Sludge Model. Similarly the concentrations of inert and biodegradable particulates in the influent were obtained from the increment of activated sludge constituents between the reactor without a primary settling tank and that with a primary settling tank. The specific decay rate of the activated sludge, which was an influential kinetic parameter on the mathematical calculation, was also regularly monitored. According to the statistical analysis, 6 collection frequencies seemed to be enough to grab the parameter. This new method required noticeably low manpower to estimate particulate BOD, soluble BOD, SS and VSS in the wastewater compared to the conventional techniques.

One of the remaining challenges in explaining differences in total factor productivity is heterogeneity between sectors and within a specific sector in terms of labor and capital. This paper employs the generalized method of moments (GMM) to identify factors that affect total factor productivity across 21 manufacturing sectors and to clarify the heterogeneous determinants of total factor productivity within manufacturing sectors for the period 2010–2015. Our estimations show that large firms have significantly greater total factor productivity levels than small firms in some fragmentations of firms in terms of both labor and total capital and in some manufacturing sectors. It is suggested that firm characteristics should be considered by the government in establishing relevant policies for enhancing firm productivity.

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