Agricultural Innovation and Technology Transfer Center (AITTC), Mohammed VI Polytechnic University, Ben Guerir, Morocco.
Laboratory of Microbial Biotechnologies, Agrosciences and Environment (BioMAgE), Cadi Ayyad University, Marrakesh, Morocco.
Environ Sci Pollut Res Int. 2021 Mar;28(11):14080-14091. doi: 10.1007/s11356-020-11619-w. Epub 2020 Nov 17.
The present study is aimed at assessing the effectiveness of solar drying process in terms of helminth egg reduction in sewage sludge (SS) generated from an activated sludge wastewater treatment plant (WWTP) in Marrakesh city (Morocco). It is also engaged to highlight a synergic effect of liming (1% CaO) and solar drying on helminth egg reduction. The solar drying process was conducted for 45 days, in summer under a semi-arid climate in a pilot scale polycarbonate-based tunnel (2 m). Before undergoing solar drying process, data showed an important load of helminth eggs including Ascaris sp., Schistosoma spp., Capillaria spp., Trichuris spp., Ankylostome spp., Toxocara spp., and Taenia spp. in limed sludge (LS) and non-limed sludge (NLS) (15.2 and 17.9 eggs/g, respectively). Ascaris eggs were the most abundant (11.2 and 13.5 eggs/g in LS and NLS, respectively). By the end of the solar drying process, a considerable removal of the total helminth eggs was recorded in LS and NLS (92.8% and 91.6%, respectively). A complete removal of Schistosoma spp., Capillaria spp., Trichuris spp., Toxocara spp. and Taenia spp. was noted in LS and NLS. In the case of Ankylostome spp., data showed a total removal in LS and 81% in NLS; however, the final load is in agreement with the standards (0.4 egg/g). As for Ascaris spp., neither liming nor solar drying process allowed a complete removal (91% and 90% in NLS and LS, respectively) and the final load (1.1 egg/g) does not fulfill the WHO requirements for an agricultural use. Principal component analysis (PCA) demonstrated a negative correlation between dry matter (DM) content (hence temperature) and helminth egg concentration. No significant synergic effect of liming and solar drying process was showed by statistical analysis. This is substantiating that temperature is the key parameter involved in helminth egg removal while undergoing solar drying of SS.
本研究旨在评估太阳能干燥过程在减少马拉喀什市（摩洛哥）活性污泥废水处理厂（WWTP）产生的污水污泥（SS）中的寄生虫卵方面的效果。本研究还旨在强调石灰（1%CaO）和太阳能干燥协同作用对寄生虫卵减少的影响。太阳能干燥过程在夏季半干旱气候下，在一个试点规模的聚碳酸酯隧道（2m）中进行了 45 天。在进行太阳能干燥过程之前，数据显示石灰污泥（LS）和非石灰污泥（NLS）中存在大量寄生虫卵，包括蛔虫、血吸虫、毛细线虫、鞭虫、钩虫、旋毛虫和带绦虫。蛔虫卵最为丰富（LS 和 NLS 中分别为 11.2 和 13.5 个/克）。太阳能干燥过程结束时，LS 和 NLS 中的总寄生虫卵去除率相当可观（分别为 92.8%和 91.6%）。LS 和 NLS 中完全去除了血吸虫、毛细线虫、鞭虫、旋毛虫和带绦虫。对于钩虫，数据显示 LS 中完全去除，NLS 中去除 81%；然而，最终负荷与标准相符（0.4 个/克）。至于蛔虫，石灰和太阳能干燥过程都不能完全去除（NLS 和 LS 中分别为 91%和 90%），最终负荷（1.1 个/克）不符合世界卫生组织对农业用途的要求。主成分分析（PCA）表明，干物质（DM）含量（因此温度）与寄生虫卵浓度之间存在负相关。统计分析表明，石灰和太阳能干燥过程没有表现出显著的协同效应。这证实了温度是 SS 太阳能干燥过程中去除寄生虫卵的关键参数。
