Spatial fractionation of phosphorus accumulating biofilm: stratification of polyphosphate accumulation and dissimilatory nitrogen metabolism

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Effects of struvite application on soil and plants: a short‐term field study

The soil P concentration commonly declines over time by organic management, if the farm does not acquire enough fertilisers or other inputs containing P from outside. An interesting source to supply farms with P is struvite (magnesium‐ammonium phosphate). This mineral easily precipitates when the concentrations of these nutrients is high enough, such as in a toilet separating urine. Struvite may be produced in a wastewater treatment plant, as a method to reduce the P concentration in the water reaching the recipient. If struvite is allowed as a mineral fertiliser in the general fertiliser regulation of the European Union,which is currently under revision, this mineral may be allowed also in certified organic agriculture. A wastewater treatment plant in Hamar (south‐eastern Norway), Hedmarken inter‐municipal wastewater corporation (Hias IKS) has developed a patented method to precipitate struvite efficiently. A sample of struvite produced by this process at Hias was sent to Tingvoll (north‐western Norway) to be tested in an experimental field with perennial ley, called “SoilEffects”. This experiment, established in 2011, is used to study the effect on yields and soil characteristics when the slurry from the farm’s herd of organic dairy cows is anaerobically digested to produce biogas before being applied as fertiliser. Non‐digested and digested slurry are compared in two levels of manure application, low and high (30 or 60 tons of slurry per ha and year), and with a control with no manure application. Eight replicates are available of each treatment, and to half of these plots, struvite was applied shortly before the slurry was applied, in the end of April 2018. We applied an amount of struvite corresponding to 40 kg P per ha. Before the application, soil samples had been collected from two depths, to study the effect of struvite on soil characteristics. Yields of ley were recorded in the two cuts, which occurred in June and August. The yield level at the 1st cut was generally low due to drought, but the increase in yield was significant with application of struvite in the plots receiving no manure, and with low manure application. At the 2nd cut, yield levels were generally higher, and again a positive effect of struvite was found in these treatments. On average, the total yield (sum of yields at the 1st and 2nd cut) was 2.4 tons of dry matter (DM) per ha with no application of manure or struvite, and 4.1 with application of struvite. In treatments receiving a low amount of manure, the mean total yield was 5 tons per ha with no struvite, and 6 tons with struvite application. In treatments receiving high amounts of manure, the mean total yield was 6.4 tons per ha without struvite, and 6.2 with struvite. The concentrations of minerals in aboveground plant material from both cuts were analysed, and new soil samples collected after the 2nd cut of ley. Application of struvite increased the P concentrations in plant material and the concentration of AL‐extractable P in soil. Struvite further increased the concentration of magnesium in plant material and soil. Soil pH increased from spring to autumn by application of manure, but the application of struvite reduced this effect. The amount of P being adsorbed to oxides of iron and aluminium in the experimental soil from a solution containing dissolved phosphate was also recorded. The soil has a certain amount of such oxides, and long‐term application of P in manure, as well as application of P in struvite, could possibly reduce the amount of P being adsorbed from the solution. However, no significant differences were found between soils which had received low or high amounts of manure over several years, and we did not find any effect of struvite application on this characteristic in this soil

Regulatory policies in relation to metrics and data collection for measuring the emergent Internet

The Internet is currently undergoing a major process of change and transformation. It is moving away from a basic model of layered architecture to a modular architecture with integrated provisioning of digital services and products to users (Garud, Kumaraswamy et al. 2003; Clark 2004; Fransman, 2010 and Yoo 2010). Furthermore traffic volumes and asymmetry of traffic information available for analysis makes it difficult to gain a full overview of and understand these changes (Hallingby et al, 2012 and Liebenau et al, 2012). Hence studying Internet as a whole is difficult, and there are many issues with data collection, with the academic and commercial literature providing plenty of references to such problems. The analysis is made even more complicated when trying to address medium and long-term sustainability of the telecom and Internet industries (Yoo, 2012). Value creation and capturing is a growing challenge to Internet ecosystem stakeholders, seeking to re-innovate a sustainable system. Hence the emergent Internet also changes the actions of national and regional regulators. Regulators are normative acting on behalf of consumers and ensuring adequate investments in society critical infrastructure (FCC, 2011). Their goals are to provide mediation using competition laws and rules as the recent French case Cogent vs. France Telecom shows (ARCEP, 2012b). This is particularly due to fast convergence of Internet and telecom. The transforming state of Internet has led many regulators around the world to make efforts to collect data for such regulatory purposes but with variable degree of success. Thus measuring Internet remains a huge challenge, and we will suggest some ways forward in this paper. Norway is a relatively small country “in the world of the emergent Internet” (Hallingby and Erdal, 2011). However the size and other aspects of the Nordic culture (e.g. openness to accountability, sense of community at all levels of society, etc.) have created an environment in which the national regulator (NPT) has multiple sources of data (NPT, 2012b), and also with correlated Internet data that are collected by diverse institutions. This has resulted in a clear and well explained ability to describe the Norwegian Internet (Hallingby and Erdal, 2011). There is also a culture of regulatory pro-active engagement with changes to the earliest emerging of issues e.g. CDNs legal forms (NPT, 2012a). This article discusses possible type of metrics required to explain the link between Internet network measures and Internet economic variables. First of all we are describing the emerging Internet in Norway, also indicating a more generic change supporting the modularity observed elsewhere. Second, and more important for the purpose of this article, we believe the metrics displayed are very valuable to companies, users, regulators and any other stakeholders. Specifically, we show the case of Norway as an example of the type of knowledge that may be developed, how these mappings can be performed, the scope and limitations of such methodology, and how it can be used by regulatory authorities to monitor but not obstruct the development of business activities. Finally, we also review the usefulness of this type of measurement in the context of a recent regulatory analysis of CDNs in Norway

Convergence in action: A case study of the Norwegian Internet

The conceptual framework for understanding the logical Internet is based on the construction of a horizontal, layered architecture, which differentiates between physical-, data link-, network-, transport-, and application layers (Woodard and Baldwin, 2008). This is different from the telecommunication networks model where a new service traditionally used to require new network architecture to be established (Yoo, 2012). However, the digitalization of services and products offered over the telecom infrastructure allows us to observe an emergent phenomenon of increased vertical integration on the Internet as well as the creation of further service specialization opportunities for telecom operators and users (Liebenau et al., 2011). We propose in this paper that this development and change in the way services are provided, leads to a new type of Internet – an addition to the current best effort Internet. We illustrate our proposition by presenting the case study of the Internet in Norway, analysing 166 of the approximately 40.000 independent AS numbers registered worldwide as catering for end-to-end services. The paper categorizes the Norwegian AS numbers according to size and type of services. Through our analyses two major groups of actors can be identified, each of them seeking to gain strategic advantage from the current Internet traffic growth: (1) Content providers and hosts seek to have a highly reliable network access with a minimal set of traffic or transmission costs. One action is to acquire AS numbers and use settlement-free peering agreements for distribution of their traffic, which is possible in traffic exchange regimes rooted in symmetry, slowly becoming asymmetric; (2) Internet access providers (IAPs) seek to take control over incoming traffic growth by hosting content within their own network and thereby to rebalance traffic and create new revenue streams with content hosting and premium end-to-end connection on-net. Our findings support the hypothesis that Internet is becoming both more vertically integrated and converged, and more specialized or modularized (Clark et al., 2004)

Spatial fractionation of phosphorus accumulating biofilm: stratification of polyphosphate accumulation and dissimilatory nitrogen metabolism

publishedVersio

Spatial fractionation of phosphorus accumulating biofilm: stratification of polyphosphate accumulation and dissimilatory nitrogen metabolism

The spatial distribution of microorganisms represents a critical issue in understanding biofilm function. The aim of the current work was to develop a method for biofilm fractionation, facilitating the analysis of individual spatial biofilm layers using metagenomic approaches. Phosphorus accumulating biofilm applied in an enhanced biological phosphorus removal wastewater treatment plant, were fractionated, and analyzed. The fractionated biofilm revealed a surprising spatial distribution of bacteria and genes, where potential polyphosphate accumulating organisms account for ∼ 47% of the inner layer microbiome. A spatial distribution of genes involved in dissimilatory nitrogen reduction was observed, indicating that different layers of the biofilm were metabolically active during the anoxic and aerobic zones of the phosphorus removal process. The physical biofilm separation into individual fractions unveiled functional layers of the biofilm, which will be important for future understanding of the phosphorus removal wastewater process