Evaluation of an aerobic composting process for the management of Specified Risk Materials (SRM)

Change of core microorganisms and nitrogen conversion pathways in chicken manure composts by different substrates to reduce nitrogen losses

Due to the rapid development of animal husbandry, the associated environmental problems cannot be ignored, with the management of livestock and poultry manure emerging as the most prominent issue. Composting technology has been widely used in livestock and poultry manure management. A deeper understanding of the nitrogen conversion process during composting offers a theoretical foundation for selecting compost substrates. In this study, the effects of sawdust (CK) and spent mushroom compost (T1) as auxiliary materials on nitrogen as well as microbial structure in the composting process when composted with chicken manure were investigated. At the end of composting, the nitrogen loss of T1 was reduced by 17.18% relative to CK. When used as a compost substrate, spent mushroom compost accelerates the succession of microbial communities within the compost pile and alters the core microbial communities within the microbial community. Bacterial genera capable of cellulose degradation (Fibrobacter, Herbinix) are new core microorganisms that influence the assimilation of nitrate reduction during compost maturation. Using spent mushroom compost as a composting substrate increased the enzyme activity of nitrogen assimilation while decreasing the enzyme activity of the denitrification pathway.

A critical review on slaughterhouse waste management and framing sustainable practices in managing slaughterhouse waste in India

Global meat consumption is on a rise with around 253 million metric tons of meat produced globally in the year 2020. Because of the rise in population and change in food preferences, meat consumption trend is likely to continue. Meat production by animal slaughtering increases the slaughterhouse wastes in the form of both solid and liquid wastes. Although various technologies for slaughterhouse waste management are available in developed countries, the effective utilization of slaughterhouse waste management is still missing in developing countries like India. India plays an active role in the meat export business globally and stood 2nd in the world with a total export valuation of 2.89 billion US $ in the year 2020. In this context, this study presents a critical overview of the current technological advancements in the global slaughterhouse waste management including utilization of by-products and further, the prevailing slaughterhouse waste management of India is discussed. Finally, a sustainable slaughterhouse waste management strategy emphasizing circular economy and regulations improvements have been suggested for India to compete in this sector at global scale.

Insight into the effects of regulating denitrification on composting: Strategies to simultaneously reduce environmental pollution risk and promote aromatic humic substance formation

Denitrification during composting is a hidden danger that causes environmental pollution risk and aromatic humic substance damage, which needs to be better regulate urgently. In this study, two denitrification regulation methods, moisture and biochar amendment, were conducted during chicken manure composting. Denitrification performance data showed two regulation methods obviously reduced NO₃^--N, NO₂^--N and N₂ contents. Humic substance increased by 25.3 % and 29.1 % under two regulations. Microbiological analysis indicated that two regulation methods could decreasing denitrifying functional microbes with aroma degradation capability. Subsequently, denitrification gene narG, nirS, nosZ were significantly inhibited (p < 0.05) and the aromatic degradation metabolism pathways were down-regulated. Correlation analysis further revealed the important influence of interspecific interactions and non-biological characteristics on functional microbes. These results provided important scientific basis to denitrification regulation in the practice of composting, which achieved the purpose of simultaneously controlling environmental pollution risk and conducing end-product formation.

Assessment of maturity during co-composting of penicillin mycelial dreg via fluorescence excitation-emission matrix spectra: Characteristics of chemical and fluorescent parameters of water-extractable organic matter

To investigate characteristics of water-extractable organic matter (WEOM) from different stages and evaluate the maturity for co-composting penicillin mycelial dreg (PMD) via fluorescence regional integration (FRI) of fluorescence excitation-emission matrix (EEM), a pilot-scale co-composting was carried out. The results showed that a classical temperature profile showed and a degradation rate of 98.1% for residual penicillin was obtained on the 6th day. DOC and DOC/DON ratio were in a low level of 4.0 g kg(-1) and 3.7, respectively, after the 32nd day. In addition, respirometric rate (SOUR) decreased to 0.87 mg O2 g(-1) VS h(-1) finally. The EEM showed that the specific Ex/Em peak related to microbial byproduct-like vanished on the 32nd day, while those related to fulvic-like and humic acid-like appearing on the 24th day. The fluorescence regional integration (FRI) results demonstrated that PV,n/PIII,n increased to 3.28 finally, suggesting a desirable maturity for co-composting PMD. The EEM-FRI consequently has the potential for characterizing the WEOM from the co-composting of PMD.

Effectiveness of bulking agents for co-composting penicillin mycelial dreg (PMD) and sewage sludge in pilot-scale system

Penicillin mycelial dreg (PMD) has a distinguishing characteristic of the high content of penicillin residue and nutrients. The existing handling of PMD used as feed additive of livestock and poultry is facing a direct challenge of penicillin transportation into environment due to the inadequate absorption through the digestive system. This work aims at examining the feasibility of co-composting of PMD with sewage sludge (SWS) in a pilot-scale system and evaluating the effect of four bulking agents. Seven treatments were co-composted over a 32-day period in 390-L reactors using the same PMD and SWS with different bulking agents, corresponding to the seven formulas (T-1: PMD + SWS + RS; T-2: PMD + SWS + WS; T-3: PMD + SWS + RS + SD; T-4: PMD + SWS + WS + SD; T-5: PMD + SWS + SD; T-6: PMD + SWS + RS + WS; control: PMD + SWS). The parameters monitored over this period included temperature, organic matter (OM), TN, NH4(+)-N, NO3(-)-N, pH, EC, penicillin residue, as well as germination index (GI). The results showed that co-composting PMD and SWS with BA is feasible. The highest rate of OM mineralization was observed in T-3, while below 30% for T-2, T-4, and T-5. Furthermore, the SD addition resulted in both the increase in the duration of thermophilic stage and maximum temperature and the decrease in TN losses, particularly in T-3, suggesting that the formula of the T-3 is very suitable option for the co-composting of PMD and SWS.