Bioreactors for the remediation of hydrocarbon-polluted water of the Bitzal River, a place of environmental emergency due to the death of manatees

Abstract

The objectives of this research are: identify the hydrocarbons in water from the Bitzal River, Tabasco; select a carbon source that serves as a representative substrate of the determined compounds; and finally, design an experimental proposal for bioreactors that are capable of consuming compounds formed by complex mixtures and, therefore be effective in the elimination of specific hydrocarbons. We identified 16 compounds that belong to different hydrocarbon fractions. Pentacene (24.3 ± 0.09 mg L^-1), n-nonane (2.11 ± 0.96 mg L^-1) and benzo [a] pyrene (1.39 ± 0.57 mg L^-1) were the compounds with the highest concentrations in water. Two culture media, mineral medium and seawater were used. Diesel and Mayan crude oil were used for each culture medium, with a total of four bioreactors. Diesel represented light- and medium-fraction hydrocarbons, while Mayan crude oil represented the heavy fraction as well as the recalcitrant and polycyclic aromatic hydrocarbons (PAH). The maximum growth of suspended solids for diesel in mineral medium reached 2.95 g L^-1, and diesel was completely consumed in 8 days. In seawater, suspended solids for diesel reached 2.70 g L^-1, and diesel was consumed in 12 days. For Mayan crude oil in mineral medium, suspended solids increased from 0.8 to 2.41 g L^-1, and Mayan crude oil was completely consumed in 12 days. Using seawater, Mayan crude oil also degraded in 12 days, and suspended solids growth reached 2.11 g L^-1. Compounds that simulate complex mixtures of hydrocarbons from light to heavy fractions could be degraded, and the use of bioreactors is an alternative method of hydrocarbon pollution remediation in the Bitzal River.

Keywords: Bubble column bioreactors; Hydrocarbons remediation; Pollution.