Microbial Profile of the Leachate from Mexico City’s Bordo Poniente Composting Plant: An Inoculum to Digest Organic Waste

Aixa Kari Gállego Bravo,Khemlal Nirmalkar,María Eugenia Gutiérrez Castillo,Selvasankar Murugesan,Luis Raúl Tovar Gálvez,Daniel Alejandro Salcedo Serrano,Jaime García-Mena,Gloria López Jiménez

doi:10.3390/en12122343

Abstract

In recent years, municipal solid waste (MSW) management has become a complex problem worldwide. Similarly, Mexico City is facing such a situation for the management and treatment of organic fraction of municipal solid waste (OFMSW). Therefore, in this work, we investigated whether leachate from the composting plant, Bordo Poniente, located in Mexico City can be used as an inoculum for the treatment of OFMSW using thermophilic anaerobic digestion (AD) with a hydraulic retention time of 30 days. We analyzed the physicochemical properties of the leachate and performed a biochemical methane potential test. Archaeal and bacterial diversity was also identified using high throughput DNA sequencing of 16S rDNA libraries. Methane yield was 0.29 m3 CH4/kg VSadded in the positive control and 0.16 m3 CH4/kg VSadded in the treatment group. The phylum, Bacteroidetes, and genus, Methanosarcina, prevailed in the leachate. However, in thermophilic conditions, the microbial communities changed, and the phylum, Firmicutes, genera, Methanoculleus, and candidate genus, vadinCA11, were dominant in the treatment group. We concluded that the leachate contains a suitable initial charge of many active bacteria and methanogenic archaea which contribute to the AD process, hence it can be used as an inoculum for the treatment of OFMSW.

Highlights

The production of solid waste is growing around the world due to economic expansion, urbanization, and a constant rise in population, leading to an increased risk for humans and the environment [1]
We aimed to study the use of compost leachate from composting plant Bordo Poniente (CPBP) as inoculum to treat OFMSW and assess the performance of anaerobic digestion (AD) at the lab-scale using thermophilic conditions
The OFMSW was acidic and had 80.54% of the volatile solids (VS)/total solids (TS) ratio which shows an abundance of organic contents in this substrate

Summary

Introduction

The production of solid waste is growing around the world due to economic expansion, urbanization, and a constant rise in population, leading to an increased risk for humans and the environment [1]. Energies 2019, 12, 2343 waste (MSW) production is nearly 1.3 billion tons per year, and it is expected to escalate to around. It has been reported that MSW generation in Latin America and the Caribbean is 1.09 kg per capita with a high content of organic waste (54%) [3]. Mexico City is facing MSW management challenges. This metropolitan area produces more than 12,000 tons of MSW per day, and from this MSW, approximately 8000 tons are disposed in five landfills in the neighboring states of Mexico City. It should be noted that 44% of the generated waste corresponds to the organic waste fraction of municipal solid waste (OFMSW) [7]. In 2004, the government of the city implemented for the first time an Integral Solid Waste Management Program (ISWMP) from 2004 to

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