Hassen A, Belguith K, Jedidi N, Cherif A, Cherif M, Boudabous A
Laboratoire Eau et Environnement, Institut National de Recherche, Scientifique et Technique, Cité Mahrajène, Tunis, Tunisia.
Bioresour Technol. 2001 Dec;80(3):217-25. doi: 10.1016/s0960-8524(01)00065-7.
This study investigates the prevailing physico-chemical conditions and microbial community; mesophilic bacteria, yeasts and filamentous fungi, bacterial spores, Salmonella and Shigella as well as faecal indicator bacteria: total coliforms, faecal coliforms and faecal Streptococci, present in a compost of municipal solid waste. Investigations were conducted in a semi-industrial pilot plant using a moderate aeration during the composting process. Our results showed that: (i) auto-sterilization induced by relatively high temperatures (60-55 degrees C) caused a significant change in bacterial communities. For instance, Escherichia coli and faecal Streptococci populations decreased, respectively, from 2 x 10(7) to 3.1 x 10(3) and 10(7) to 1.5 x 10(3) cells/g waste dry weight (WDW); yeasts and filamentous fungi decreased from 4.5 x 10(6) to 2.6 x 10(3) cells/g WDW and mesophilic bacteria were reduced from 5.8 x 10(9) to 1.8 x 10(7) bacteria/g WDW. On the other hand, the number of bacterial spores increased at the beginning of the composting process, but after the third week their number decreased notably; (ii) Salmonella disappeared completely from compost by the 25th day as soon as the temperature reached 60 degrees C; and (iii) the bacterial population increased gradually during the cooling phase. While Staphylococci seemed to be the dominant bacteria during the mesophilic phase and at the beginning of the thermophilic phase, bacilli predominated during the remainder of the composting cycle. The appearance of gram-negative rods (opportunistic pathogens) during the cooling phase may represent a serious risk for the sanitary quality of the finished product intended for agronomic reuse. Compost sonication for about 3 min induced the inactivation of delicate bacteria, in particular gram-negatives. By contrast, gram-positive bacteria, especially micrococcus, spores of bacilli, and fungal propagules survived, and reached high concentrations in the compost.
本研究调查了城市固体废物堆肥中普遍存在的物理化学条件和微生物群落；嗜温细菌、酵母和丝状真菌、细菌芽孢、沙门氏菌和志贺氏菌以及粪便指示菌：总大肠菌群、粪大肠菌群和粪链球菌。研究在一个半工业试验工厂中进行，堆肥过程采用适度曝气。我们的结果表明：（i）相对高温（60 - 55摄氏度）引起的自动杀菌导致细菌群落发生显著变化。例如，大肠杆菌和粪链球菌数量分别从2×10⁷降至3.1×10³以及从10⁷降至1.5×10³个细胞/克废弃物干重（WDW）；酵母和丝状真菌从4.5×10⁶降至2.6×10³个细胞/克WDW，嗜温细菌从5.8×10⁹降至1.8×10⁷个细菌/克WDW。另一方面，细菌芽孢数量在堆肥过程开始时增加，但在第三周后其数量显著减少；（ii）一旦温度达到60摄氏度，沙门氏菌在第25天时从堆肥中完全消失；（iii）在冷却阶段细菌数量逐渐增加。虽然葡萄球菌在嗜温阶段和嗜热阶段开始时似乎是优势细菌，但芽孢杆菌在堆肥周期的其余阶段占主导地位。冷却阶段革兰氏阴性杆菌（机会致病菌）的出现可能对用于农业再利用的成品卫生质量构成严重风险。对堆肥进行约3分钟的超声处理可使脆弱细菌失活，特别是革兰氏阴性菌。相比之下，革兰氏阳性菌，尤其是微球菌、芽孢杆菌芽孢和真菌繁殖体存活下来，并在堆肥中达到高浓度。
