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Deinking sludge (DS) is a residue from the waste paper recycling industry. It is a by-product originating from the deinking process which is designed to remove inks and other impurities from waste papers to recover usable fibers. The aim of this study was to investigate the possibility of anaerobic digestion (AD) of DS in order to produce methane (CH 4 ) by degrading organic matter. DS differs clearly from common AD substrates due to its specific composition. The focus was laid on comparing various inocula in order to find appropriate microbial consortia. Three inocula from different origins were investigated. After sludge and inocula characterization, batch AD at a mesophilic (37 °C) condition was performed for 21 days to determine biogas and CH 4 potentials as well as sludge biodegradability in comparison to cellulose. The highest average CH 4 yield achieved in the 21 days of the batch experiment was 167 NmL/g organic dry matter (oDM). However, the CH 4 potentials from all experiments did not have a wide range (average 160 NmL/g oDM; standard deviation ±5.0 NmL/g oDM). The highest organic matter degradation achieved was 31%. It can be stated that conventional AD inocula are usable to degrade DS, but that a significant part of the oDM was anaerobically not degradable. The overall CH 4 yields were lower compared to top AD substrates such as energy crops, but in a similar range like residue-based AD substrates such as manure. Since actual DS management is cost-intensive and affecting the profitability of waste paper industry significantly, AD as a management option with an energetically valuable output is a very promising option., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Anaerobic digestion is a waste treatment method which is of increasing interest worldwide. At the end of the process, a digestate remains, which can gain added value by being composted. A study was conducted in order to investigate microbial community dynamics during the composting process of a mixture of anaerobic digestate (derived from the anaerobic digestion of municipal food waste), green wastes and a screened compost (green waste/kitchen waste compost), using the COMPOCHIP microarray. The composting process showed a typical temperature development, and the highest degradation rates occurred during the first 14 days of composting, as seen from the elevated CO2 content in the exhaust air. With an exception of elevated nitrite and nitrate levels in the day 34 samples, physical-chemical parameters for all compost samples collected during the 63 day process indicated typical composting conditions. The microbial communities changed over the 63 days of composting. According to principal component analysis of the COMPOCHIP microarray results, compost samples from the start of the experiment were found to cluster most closely with the digestate and screened compost samples. The green waste samples were found to group separately. All starting materials investigated were found to yield fewer and lower signals when compared to the samples collected during the composting experiment., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Municipal solid waste (MSW) generation and management in Cuba was studied with a view to integrating composting of the organic fractions of MSW into the system. Composting is already included as part of the environmental strategy of the country as an appropriate waste management solution. However, no programme for area-wide implementation yet exists. The evaluation of studies carried out by some Cuban and international organisations showed that organic matter comprises approximately 60-70% of the MSW, with households being the main source. If all organic waste fractions were considered, the theoretical amount of organic waste produced would be approximately 1 Mio. Mg/a, leading to the production of approximately 0.5 Mio. Mg/a of compost. Composting could, therefore, be a suitable solution for treating the organic waste fractions of the MSW. Composting would best be carried out in decentralised systems, since transportation is a problem in Cuba. Furthermore, low technology and low budget composting options should be considered due to the problematic local economic situation. The location for such decentralised composting units would optimally be located at urban agricultural farms, which can be found all over Cuba. These farms are a unique model for sustainable farming in the world, and have a high demand for organic fertiliser. In this paper, options for the collection and impurity-separation in urban areas are discussed, and a stepwise introduction of source-separation, starting with hotel and restaurant waste, is suggested. For rural areas, the implementation of home composting is recommended.

Composting is a preferred treatment strategy for biodegradable plastics (BDPs). In this sense, the collection of BDPs together with organic household wastes is a highly discussed possibility. Under the aspect of the behaviour of BDPs in composting facilities, a telephone survey was carried out with selected composting facility operators. They were interviewed with respect to treated wastes, content of impurities, processes for impurity separation, experiences with biodegradable plastics and assumptions to the behaviour of biodegradable plastics in their facility. Forty percent of the facilities had some experiences with BDPs due to test runs, and also since the occurrence of BDPs in their waste was known. The majority of the operators expressed apprehension regarding an increase of impurities resulting from a combined collection of biowaste and BDPs. In the facilities, measures for the impurity separation from the biowaste were used in common practice - in 33% of the cases, separation of disturbing plastics was done before composting, in 33% after composting, and in 13% before and after composting. The most important separation processes for conventional plastics were sieving and manual sorting. In two cases air classification was also used. When asked about the separation possibility of the conventional but not of the biodegradable plastics in their facilities, the majority of operators were not in a position to comment or they replied that it was not an option. No problems were seen in most cases if the impurity separation follows composting. If impurity separation takes place before composting it was often assumed that the BDPs are mainly separated by sieving. In conclusion, in more than half of the cases, BDPs would not be composted if delivered to a composting facility. Under the actual conditions regarding the collection and the treatment/disposal possibilities, an application of BDPs seems to only be reasonable for clean (i.e., source separated on their own) fractions of BDPs.

To determine the optimal course of composting it is useful to carry out experiments. The selection of the right experimental set-up depends on the question of concern. Each set-up is useful for a particular application and has its limits. Two test systems of different scales (up to 1500 ml; up to 100 l) are introduced. The purpose and importance of each system design shall be highlighted by application examples: (1). Suitability of a liquid industrial residue as composting accelerator; (2). Determination of the compost maturity; (3). Behaviour of odor-reducing additives during waste collection and composting; (4). Production of tailor-made compost with respect to Nitrogen (5). Suitability of O(2)-enriched air for acceleration of composting. Small-scale respiration experiments are useful to optimize parameters which have to be adjusted during substrate pre-treatment and composting, with the exception of particle size and temperature, and to reduce the number of variants which have to be investigated in greater detail in larger scale experiments. As all regulation possibilities such as aeration, moistening, turning can be simulated with the technical scale set-up, their complex cooperation can be taken into consideration. Encouraging composting variants can be tested, compared and optimized.