A faecal sludge (FS) co-composting study assessed the extent of consistency in compost characteristics between and within batches. The study focused on the consistency of the co-composting process by measuring the variability of key parameters. The set up consisted of 12 FS and food waste (FW) co-composting piles in three successive batches (1, 2 and 3). Consistency was assessed in the three successive batches of co-composted FS and food waste (FW). Within batches, consistency was assessed in each of them by dividing it into four separate replicate piles. Characteristics of interest were E. coli, as well as selected physico-chemical parameters (pH, EC, Mg, Ca, N, NH4-N, NO3-N, P, avail. P, and K) and heavy metals (Se, Fe, Cd, Cu, Hg, Ni, Pb and Cr). Data were subjected to analysis of variance (ANOVA) using SPSS. Results show that, E. coli levels were not consistent between the successive batches during the entire co-composting process. While variations between batches were only observed for EC and nutrient parameters, variations were evident for several measured characteristics within batches. The measured coefficient of variations (CVs) within batches ranged between 0–125% and 3–111% for heavy metals and nutrients, respectively. In conclusion, there was less consistency in nutrients between successive batches and CV within batches was wide. Consistency levels for E. coli may not be an issue if pathogen inactivation is complete. It is recommended that a threshold value be created for determining what is an acceptable level of variation in FS co-composting.

中文翻译：

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评估加纳某市粪便污泥和食物垃圾好氧共堆肥的一致性

粪便污泥（FS）共堆肥研究评估了批次之间和批次内堆肥特性的一致性程度。该研究通过测量关键参数的变异性来关注共同堆肥过程的一致性。该设施包括 12 个 FS 和食物垃圾 (FW) 共堆肥堆，分三个连续批次（1、2 和 3）。对连续三批共堆肥 FS 和食物垃圾 (FW) 的一致性进行了评估。在批次内，通过将每个批次分成四个独立的重复堆来评估一致性。感兴趣的特征是大肠杆菌，以及选定的物理化学参数（pH、EC、Mg、Ca、N、NH4-N、NO3-N、P、avail. P 和 K）和重金属（Se、铁、镉、铜、汞、镍、铅和铬）。使用 SPSS 对数据进行方差分析 (ANOVA)。结果表明，在整个混合堆肥过程中，连续批次之间的大肠杆菌水平并不一致。虽然仅在 EC 和营养参数方面观察到批次之间的差异，但批次内的几个测量特性的差异是明显的。测得的重金属和营养素的批次内变异系数 (CV) 分别在 0-125% 和 3-111% 之间。总之，连续批次之间的营养成分一致性较差，批次内的CV较宽。如果病原体完全灭活，大肠杆菌的一致性水平可能不是问题。建议创建一个阈值来确定 FS 联合堆肥可接受的变化水平。