Safety Evaluation of Polyethylene Terephthalate Chemical Recycling Processes

Polyethylene terephthalate (PET) is one of the main packaging materials for beverage bottles. Even if this polymer is good to recycle, mechanical recycling processes need a well-sorted input fraction. For less-sorted PET packaging, or even non-food input sources, chemical recycling seems to be a solution to increase PET recycling. For post-consumer recyclates in packaging applications, it is essential that the safety of the recyclates is guaranteed, and the consumers’ health protected. For mechanical recycling processes, evaluation criteria are already established. For chemical recycling processes, however, such evaluation criteria are only roughly available. This study evaluated the safety of the chemical recycling process similar to the approach of the European Food Safety Authority (EFSA). However, due to the lack of information about the contamination level of the input materials for the chemical recycling process, the evaluation was adapted. In addition, the evaluation should be performed separately for the depolymerisation and for the repolymerisation steps. However, due to the high cleaning efficiencies of both steps, the evaluation can focus on the repolymerisation. This simplifies the assessment of the chemical recycling processes considerably.

Interannual variation in the epibenthic megafauna at the shallowest station of the HAUSGARTEN observatory (79° N, 6° E)

Epibenthic megafauna play an important role in the deep-sea environment and contribute significantly to benthic biomass, but their population dynamics are still understudied. We used a towed deep-sea camera system to assess the population densities of epibenthic megafauna in 2002, 2007, and 2012 at the shallowest station (HG I, ∼1300 m) of the deep-sea observatory HAUSGARTEN, in the eastern Fram Strait. Our results indicate that the overall density of megafauna was significantly lower in 2007 than in 2002, but was significantly higher in 2012, resulting in overall greater megafaunal density in 2012. Different species showed different patterns in population density, but the relative proportions of predator/scavengers and suspension-feeding individuals were both higher in 2012. Variations in megafaunal densities and proportions are likely due to variation in food input to the sea floor, which decreased slightly in the years preceding 2007 and was greatly elevated in the years preceding 2012. Both average evenness and diversity increased over the time period studied, which indicates that HG I may be food-limited and subject to bottom-up control. The community of HG I may be unique in its response to elevated food input, which resulted in higher evenness and diversity in 2012.

Interannual variation in the epibenthic megafauna at the shallowest station of the HAUSGARTEN observatory (79° N, 6° E)

Epibenthic megafauna play an important role in the deep-sea environment and contribute significantly to benthic biomass, but their population dynamics are still understudied. We used a towed deep-sea camera system to assess the population densities of epibenthic megafauna in 2002, 2007 and 2012 at the shallowest station (HG I, ~ 1300 m) of the deep-sea observatory HAUSGARTEN, in the eastern Fram Strait. Our results indicate that the overall density of megafauna was significantly lower in 2007 than in 2002, but was significantly higher in 2012, resulting in overall greater megafaunal density in 2012. Different species showed different patterns in population density, but the relative proportions of predator/scavengers and suspension-feeding individuals were both higher in 2012. Variations in megafaunal densities and proportions are likely due to variation in food input to the sea floor, which decreased slightly in the years preceding 2007 and was greatly elevated in the years preceding 2012. Both average evenness and diversity increased over the time period studied, which indicates that HG I may be food-limited and subject to bottom-up control. The varying dynamics of different species may have been caused by differential capacities of populations to respond to increased food input through either recruitment or migration.

Ideal free distribution theory as a tool to examine juvenile coho salmon (Oncorhynchus kisutch) habitat choice under different conditions of food abundance and cover

We investigated the mechanisms affecting habitat choice by juvenile coho salmon (Oncorhynchus kisutch) in relation to the patchy distribution of food and cover. We tested the following hypotheses: (i) the distribution of juvenile coho, both between patches in a pool and between separate pools in a channel, corresponds numerically to the food input rate of those habitat patches as predicted by the "input-matching rule" of ideal free distribution (IFD) and (ii) the addition of instream cover, by increasing visual isolation among competitors, promotes input matching both within and between pools. We conducted our experimental work in artificial channels and we used two different types of cover, instream and overhead. In the absence of cover and with either no differences or relatively small differences in food abundance between patches, the spatial distribution of juvenile coho responded numerically to the input rate of food as predicted by the IFD. However, when differences in food abundance between patches were relatively large or cover was present, fish distributions consistently undermatched food input rate in the rich patch. Coho foraged in open patches away from cover within single pools but preferred pools with cover when choosing between separate pools. Several IFD models were used to examine the observed dispersion patterns.

Use of the rumen simulation technique (rusitec) to provide micro-organisms for assessing forage rate-of-fermentationin vitro:effect of solid food input to rusitec

In a previous experiment (Barbi, Owen & Theodorou, 1993) effluent fluid from thein vitrorumen simulation technique (RUSITEC - Czerkawski & Breckenridge, 1977) was used as a source of inoculum when fermenting forage in the Pressure Transducer Technique (PTT - Theodorou, Williams, Brooks, Dhanoa, McAllan & Gill, 1993). The main objective was to replace rumen fistulated animals for assessing the fermentation kinetics of forages. However, low microbial activity in RUSITEC effluent-fluid affected the results, such that fermentation profiles were lower than those in controls inoculated with rumen liquor (Barbiet al,1993).In the present study, in an attempt to increase the microbial cellulolytic activity in the effluent fluid, we altered the particle size and increased the amount of substrate added daily to the RUSITEC vessels. Two particle sizes were examined in an attempt to enhance microbial activity and growth by increasing the availability of colonization surfaces.

Use of the rumen simulation technique (rusitec) to provide micro-organisms for assessing forage rate-of-fermentationin vitro:effect of soluble carbohydrate inputs to rusitec

In previous experiments (Barbi, Owen & Theodorou, 1993; Barbi, Owen & Theodorou, 1994), to minimize the reliance on fistulated animals in feed evaluation, effluent fluid from thein vitrorumen simulation technique (RUSITEC - Czerkawski & Breckenridge, 1977) was used to replace strained rumen liquor as the inoculum for the Pressure Transducer Technique (PTT - Theodorou, Brooks, Dhanoa, McAllan & Gill, 1993). In Barbiet al(1993), two different dilution rates in RUSITEC were compared, whereas in Barbiet al(1994), the effect of increasing the solid food input to RUSITEC was assessed. In both experiments low microbial activity in the RUSITEC effluent fluid affected the PTT results, reducing rates and extent of fermentation profiles to below those in the rumen-liquor inoculated control cultures.In the present study, mixtures of glucose and xylose, as sources of liquid-phase nutrients, were infused, in differing quantities, into RUSITEC vessels. Also, the effect of adding or not adding a source of solid nutrient (hay) to the effluent collection vessels, was investigated. The objective, in both treatments, was to increase the cellulolytic microbial activity of RUSITEC effluent fluid.