Can we use Cd-contaminated macrophytes for biogas production?

• Published in: Environmental science and pollution research international Vol. 26; no. 27; pp. 27620 - 27630
• Main Authors: Fernandes, Katiúcia Dias, Cañote, Susan Johana Benites, Ribeiro, Eruin Martusceli, Thiago Filho, Geraldo Lúcio, Fonseca, Ana Lúcia
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2019; Springer Nature B.V
• Subjects: Alternative energy sources; Analytical Methods; Aquatic plants; Aquatic Pollution; Araceae - chemistry; Atmospheric Protection/Air Quality Control/Air Pollution; Bioassays; Biodegradation, Environmental; Biofuels; Biogas; Cadmium; Cadmium - chemistry; Chronic effects; Contaminants; Contamination; Digesters; Earth and Environmental Science; Ecotoxicology; Eichhornia - chemistry; Eichhornia crassipes; Environment; Environmental Chemistry; Environmental Health; Environmental Samples; Environmental science; Global Toxicity Assessment: Chemicals; Industrial plants; Industrial pollution; Industrial wastes; Industrial wastewater; Macrophytes; Methane; Phytoremediation; Pistia stratiotes; Plants (botany); Toxicity; Viability; Waste Water - analysis; Waste Water - chemistry; Waste Water Technology; Wastewater; Wastewater treatment; Water Management; Water Pollution Control; Micro-biodigestion; Metane; Eichhornia crassipes; Pistia stratiotes
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-018-2318-2

Aside from the ability of plants to remove domestic-industrial wastewater contaminants from various types of water, macrophytes can also serve as an alternative source of energy. The goal of the present study was to test the viability of biogas production using aquatic macrophyte species—
Eichhornia crassipes
and
Pistia stratiotes
—contaminated with cadmium (Cd) after the phytoremediation process. The plants were transferred to a nutrient solution contaminated with 0.8 mg L
−1
of Cd. The experiment was set up in a 2 × 3 factorial scheme with the presence or absence of Cd and three phytoremediation times (20, 40, or 60 days) using
P. stratiotes
followed by an additional treatment consisting of
P. stratiotes
 + 
E. crassipes
for 20 days. The acute and chronic effects of bioassays with the microcrustacean
Daphnia similis
were used to evaluate the ability of the macrophytes to remove toxicity by phytoremediation. The viability test of biogas production after phytoremediation was evaluated using micro-biodigesters. According to the results, at least 60 days of phytoremediation are necessary to remove/remediate the Cd present in the contaminated solution. The metal did not influence the macrophytes’ methanogenic activity, showing that these macrophytes can be used for biogas/methane production. The combination of
Pistia stratiotes
with
Eichhornia crassipes
is a good alternative to reduce phytoremediation time, but for 20 days of testing, the presence of
Eichhornia crassipes
reduces the biogas production/CH
4
. However, it is believed that if the digestion time is extended, this effect can be minimized. The phytoremediation time indicated that
Pistia stratiotes
must remain at least 60 days to remove/remediate the Cd present in the contaminated solution.