Comparison of five organic wastes regarding their behaviour during composting: Part 2, nitrogen dynamic

Abstract

Author-produced version of the article published in Waste Management Original publication available at www.elsevier. com -doi:10.1016/j.wasman.2009.10.018 2 Abstract 1 This paper aimed to compare household waste, separated pig solids, food waste, pig slaughterhouse sludge 2 and green algae regarding processes ruling nitrogen dynamic during composting. For each waste, three 3 composting simulations were performed in parallel in three similar reactors (300L), each one under a constant 4 aeration rate. The aeration flows applied were comprised between 100 and 1100 L/h. The initial waste and the 5 compost were characterized through the measurements of their contents in dry matter, total carbon, Kjeldahl and 6 total ammoniacal nitrogen, nitrite and nitrate. Kjeldahl and total ammoniacal nitrogen and nitrite and nitrate 7were measured in leachates and in condensates too. Ammonia and nitrous oxide emissions were monitored in 8 continue. The cumulated emissions in ammonia and in nitrous oxide were given for each waste and at each 9 aeration rate. The paper focused on process of ammonification and on transformations and transfer of total 10 ammoniacal nitrogen. The parameters of nitrous oxide emissions were not investigated. The removal rate of 11 total Kjeldahl nitrogen was shown being closely tied to the ammonification rate. Ammonification was modelled 12 thanks to the calculation of the ratio of biodegradable carbon to organic nitrogen content of the biodegradable 13 fraction. The wastes were shown to differ significantly regarding their ammonification ability. Nitrogen 14 balances were calculated by subtracting nitrogen losses from nitrogen removed from material. Defaults in 15 nitrogen balances were assumed to correspond to conversion of nitrate even nitrite into molecular nitrogen and 16 then to the previous conversion by nitrification of total ammoniacal nitrogen. The pool of total ammoniacal 17 nitrogen, i.e. total ammoniacal nitrogen initially contained in waste plus total ammoniacal nitrogen released by 18 ammonification, was calculated for each experiment. Then, this pool was used as the referring amount in the 19 calculation of the rates of accumulation, stripping and nitrification of total ammoniacal nitrogen. Separated pig 20 solids were characterised by a high ability to accumulate total ammoniacal nitrogen. Whatever the waste, the 21 striping rate depended mostly on the aeration rate and on the pool concentration in biofilm. The nitrification rate 22 was observed as all the higher as the concentration in total ammoniacal nitrogen in the initial waste was low. 23Thus, household waste and green algae exhibited the highest nitrification rates. This result could mean that in 24 case of low concentrations in total ammoniacal nitrogen, a nitrifying biomass was already developed and that 25 this biomass consumed it. In contrast, in case of high concentrations, this could traduce some difficulties for 26 nitrifying microorganisms to develop. 27

Co-composting of livestock manure with rice straw: Characterization and establishment of maturity evaluation system

“…Composting is a biological process in which organic matter (OM) can be utilized by aerobic thermophilic and mesophilic microorganisms as substrate and mainly converted into mineralized products (CO 2 , H 2 O, NH 4 + ) or stabilized OM (mostly as humic substances) (Bernal et al, 2009;He et al, 2009;de Guardia et al, 2010a;de Guardia et al, 2010b). Although composting has been widely practiced with its final products being used as fertilizer or soil amendment, there are still knowledge gaps in understanding it due to the high variety and heterogeneity of feedstocks (Li et al, 2008;Himanen and Hänninen, 2011).…”

Compostaje de biorresiduos: Tendencias de investigación y pertinencia en países en desarrollo

“…De otro lado, la pérdida de nitrógeno en el proceso, principalmente en forma de amoniaco, es uno de los temas más abordados en las investigaciones debido a su relación con la calidad del producto y a las emisiones de NOx que se relacionan con los GEI [65]. Como alternativa para mejorar la calidad del producto final, los ensayos de escala de laboratorio pueden indicar si las opciones que se pretendan evaluar pueden ofrecer resultados satisfactorios en términos de biodegradabilidad o si por el contrario podrían afectar el proceso.…”

Response of African Nightshade (Solanum sp.) to cassava peel-based manure in the humid forest zone of Cameroon

“…This disagrees with the results of De Guardia et al (2008), Körner and Stegmann (2003) and Liang et al (2004) who found higher ammonia emissions with higher aeration rates. This difference could result from the reaction of the different nitrifying bacteria with aeration and the nature of the compost material (De Guardia et al, 2009). The results of this study therefore suggest that both frequencies of turning could be used with little effects on the properties of the finished compost.…”