Integration of high-solid digestion and gasification to dispose horticultural waste and chicken manure

To realize full energy recovery from grass and chicken manure(CM), the integration of high-solid anaerobic digestion(HSAD) and gasification was investigated experimentally. The anaerobic biodegradability of grass can be enhanced through codigestion with CM. When the volatile solid(VS) ratio of CM to grass was 20:80, C/N ratio calculated to be 21.70, the cumulative biogas yield was the highest, 237 ml·(g VS)^(-1). The enhancement of biogas production was attributed to the buffering effects of ammonia and rich trace elements in CM. In semi-continuous systems, when the organic loading rate was 4.0 g VS·L^(-1)·d^(-1), the HSAD process was stable, with the average biogas yield 168 ml·(g VS)^(-1). More than 80% fractions of the digestates were volatile matters, which meant that the digestates can be used as feedstock for gasification to produce syngas. The VS ratio of grass to CM had significant overall energy generation through HSAD and gasification. Compared with gasification of digestate,cogasification with woodchips increased syngas yield and low heat value(LHV). Increasing of mass ratio of digestates to woodchips led to the decrease of LHV.

Understanding and optimizing the gasification of biomass waste with machine learning

Gasification is a sustainable approach for biomass waste treatment with simultaneous combustible H2-syngas production.However,this thermochemical process was quite complicated with multi-phase products generated.The product distribution and composition also highly depend on the feedstock information and gasification condition.At present,it is still challenging to fully understand and optimize this process.In this context,four datadriven machine learning(ML)methods were applied to model the biomass waste gasification process for product prediction and process interpretation and optimization.The results indicated that the Gradient Boosting Regression(GBR)model showed good performance for predicting three-phase products and syngas compositions with test R^(2)of 0.82–0.96.The GBR model-based interpretation suggested that both feed and gasification condition(including the contents of feedstock ash,carbon,nitrogen,oxygen,and gasification temperature)were important factors influencing the distribution of char,tar,and syngas.Furthermore,it was found that a feedstock with higher carbon(>48%),lower nitrogen(<0.5%),and ash(1%–5%)contents under a temperature over 800℃could achieve a higher yield of H_(2)-rich syngas.It was shown that the optimal conditions suggested by the model could achieve an output containing 60%–62%syngas and achieve an H_(2)yield of 44.34 mol/kg.These valuable insights provided from the model-based interpretation could aid the understanding and optimization of biomass gasification to guide the production of H_(2)-rich syngas.

Trends and driving forces of low-carbon energy technology innovation in China’s industrial sectors from 1998 to 2017: from a regional perspective

Low-carbon energy technology(LC)innovation contributes to both environmental protection and economic development.Using the panel data of 30 provinces/autonomous regions/municipalities in China from 1998 to 2017,this paper constructs a two-layer logarithmic mean Divisia index(LMDI)model to uncover the factors influencing the variation of the innovation of LC in China’s industrial sectors,including the alternative energy production technology(AEPT)and the energy conversation technology(ECT).The results show that China’s industrial LC patent applications rapidly increased after 2005 and AEPT patent applications outweighed ECT patent applications all the time with a gradually narrowing gap.Low-carbon degree played the dominant role in promoting the increase in China’s industrial LC patent applications,followed by the economic scale,R&D(research and development)efficiency,and R&D share.Economic structure contributed to the increases in LC patent applications in the central and the western regions,while led to the decreases in the eastern region,the north-eastern region,and Chinese mainland.Low-carbon degree and economic scale were two main contributors to the growths of both industrial AEPT patent applications and ECT patent applications in Chinese mainland and the four regions.Several policy recommendations are made to further promote industrial innovation in China.

Valorization of poly-β-hydroxybutyrate(PHB)-based bioplastic waste in anaerobic digesters of food waste for bioenergy generation:reactor performance,microbial community analysis,and bioplastic biodegradation

This study aims to investigate the significance and biodegradation pathways of PHB-based bioplastic in anaerobic digesters treating food waste,where the reactor performance of changed methane generation,bioplastic biodegradation efficiency,and bioinformatic analysis of functional microbes were emphasized.The results showed that PHB-based plastic film could be partially biodegraded in the food waste digester,and a bioaugmentation use of Alcaligenes Faecalis(AF)and Bacillus Megaterium(BM)was beneficial to largely accelerate the degradation process through a beneficial shift of both the functional bacterial and archaeal species.Microbial community analysis indicated that the major bacterial species belonged to genera Candidatus_Cloacimonas,Rikenellaceae,and Defluviitoga,while the dominant methanogenic archaeal species belonged to genera Methanomassiliicoccus,Methanosarcina,and Methanosaeta.Bioplastic biodegradation analysis suggested that the optimal fractions of AF and BM for PHB-based plastic degradation were 50% AF and 75% BM,respectively,which deserves further optimization and scale-up validation.The finding of this study would contribute to the combined management of PHB-based bioplastic with food waste for clean energy recovery and a greener environment.