Nsiah-Gyambibi Rapheal, Essandoh Helen Michelle Korkor, Asiedu Nana Yaw, Fei-Baffoe Bernard
Regional Water and Environmental Sanitation Centre, Kumasi. Department of Civil Engineering, College of Engineering Kwame Nkrumah University of Science and Technology, UPO, Kumasi, Ghana.
Department of Chemical Engineering, College of Engineering, Kwame Nkrumah University of Science and Technology, PMB, UPO, Kumasi, Ghana.
Heliyon. 2021 Mar 8;7(3):e06422. doi: 10.1016/j.heliyon.2021.e06422. eCollection 2021 Mar.
High generation of fecal sludge without proper treatment is a major sanitation problem. A key step in curbing this problem is producing value-added resources such as vermicompost from fecal sludge through substrate enrichment. Substrate enrichment is a vermicomposting technique that involves augmenting vermibed substrates with organic rich materials to provide additional nutrients, as well as underlying layers needed for microcosm development to produce desirable vermicompost. The aim of this study was to investigate effects of substrate enrichment with organic soils (black soil, red laterite soil and sandy soil) combined with coconut coir as bulking material, on the fecal sludge vermicomposting process and quality of the end-product. The purpose of the study was to promote the development of highly nutritive vermicompost from fecal sludge using substrate enrichment as a low-cost innovative vermicomposting technique. The enriched substrates were prepared with 160g of coconut coir, 120g of fecal matter (65-70% dry matter) and 80g of organic soil. The treatments were labelled T, T and T representing systems containing black soil, red laterite soil and sandy soil respectively. The control treatment (T) contained no soil. Triplicate treatments were setup and about 20 3-week old clitellated earthworms of the species with live weights ranging from 255 to 275mg, released into each system for vermicomposting over a period of 12 weeks. Physicochemical parameters such as pH, Organic Carbon (C), Total Nitrogen (N), Available Phosphorus (P), Exchangeable Calcium (Ca), Iron (Fe), Lead (Pb) and Aluminium (Al) were determined for both the fecal sludge and the vermicompost. The vermicompost in the setup with black soil (T) showed the highest C mineralization and N, P and Ca enhancement followed by T, T and T. Treatment T also resulted in the lowest concentration of Fe, Pb and Al in the vermicompost. Concentrations of these heavy metals were found to be higher in the other treatments in increasing order of T, T and T. Less than 16% earthworm mortality was recorded in all treatments except T, in which the mortality was about 38% (38.33 ± 13.74). The enriched substrates were therefore found to provide a more suitable microclimate for earthworm development and produced vermicompost with high nutrient content. However, a more comprehensive study on metal accumulation in the earthworm tissues as a potential metal contaminant is needed to establish a strong hypothesis in the safe use of earthworms for this vermicomposting technique.
未经适当处理而大量产生粪便污泥是一个重大的环境卫生问题。遏制这一问题的关键步骤是通过底物富集从粪便污泥中生产增值资源，如蚯蚓堆肥。底物富集是一种蚯蚓堆肥技术，它涉及用富含有机物的材料增加蚯蚓床底物，以提供额外的养分，以及微观环境发育所需的底层，从而生产出理想的蚯蚓堆肥。本研究的目的是调查用有机土壤（黑土、红壤和砂土）与椰壳纤维作为填充材料进行底物富集，对粪便污泥蚯蚓堆肥过程和最终产品质量的影响。该研究的目的是利用底物富集作为一种低成本的创新蚯蚓堆肥技术，促进从粪便污泥中开发高营养的蚯蚓堆肥。富集底物由160克椰壳纤维、120克粪便（干物质含量65 - 70%）和80克有机土壤制备而成。处理分别标记为T₁、T₂和T₃，分别代表含有黑土、红壤和砂土的系统。对照处理（T₀）不含土壤。设置了三个重复处理，并将约20条3周龄的环带成熟蚯蚓放入每个系统中进行蚯蚓堆肥，这些蚯蚓的活重范围为255至275毫克，为期12周。对粪便污泥和蚯蚓堆肥都测定了理化参数，如pH值、有机碳（C）、总氮（N）、有效磷（P）、交换性钙（Ca）、铁（Fe）、铅（Pb）和铝（Al）。含有黑土的设置（T₁）中的蚯蚓堆肥显示出最高的碳矿化以及氮、磷和钙的增加，其次是T₂、T₃和T₀。处理T₀还导致蚯蚓堆肥中铁、铅和铝的浓度最低。在其他处理中，这些重金属的浓度按T₃、T₂和T₁的顺序递增。除T₀外，所有处理中记录的蚯蚓死亡率均低于16%，其中T₀的死亡率约为38%（38.33±13.74）。因此，发现富集底物为蚯蚓发育提供了更适宜的微气候，并生产出营养含量高的蚯蚓堆肥。然而，需要对蚯蚓组织中的金属积累作为潜在的金属污染物进行更全面的研究，以便为安全使用蚯蚓进行这种蚯蚓堆肥技术建立一个有力的假设。
