Bioremediation of nitrogen- and phosphorus-polluted aquaculture sediment by utilizing combined immobilized effective microorganisms and sediment aeration technology

Abstract

The endogenous release of nitrogen and phosphorus from aquaculture sediment can continuously pollute the water quality in aquaculture ponds. In this study, an integrated bioremediation approach that combined effective microorganisms (EM) with aeration techniques was designed to restore contaminated aquaculture sediment. Initially, a set of laboratory-scale experiments was designed to evaluate the feasibility of the technology for the bioremediation of nitrogen and phosphorus. The removal and transformation efficiency indexes of both the overlying water and sediment were measured. From the obtained results, the combination of sediment aeration and immobilized EM significantly improved the nitrogen and phosphorus removal rate from the overlying water and sediment when compared to other methods. Subsequently, a series of field-scale experiments was further implemented to assess the integrated technique in practical applications. In field experiments, the variation in the comprehensive trophic level index (TLI) and sediment biodegradation activities (G value) was used to assess the effect of sediment bioremediation. In pond II which promotes sediment biodegradation, the values of TLI varied from 70.13 to 54.16, and the classification level changed from Hypereutrophic to a Light eutrophic. In addition, the G value increased from 0.98 kg/(kg•h) to 2.12 kg/(kg•h). The organic matter (OM) and sediment thickness (ST) decreased by 17.4 g/kg and 2.3 cm, respectively. The obtained results indicated that the combination of EM and sediment aeration might be feasible and effective for the remediation of nitrogen-and phosphorus-polluted aquaculture sediment.

Bacillus amyloliquefaciens (IAE635) and their metabolites could purify pollutants, Vibrio spp. and coliform bacteria in coastal aquaculture wastewater

“…Microbial reagents have been shown to be effective in removing COD and inorganic nitrogenous waste originated from the uneaten feed and excretion in aquaculture [4,24] . For example, EM used in the aquaculture water purification could transform NH 4 + -N or NO 3 --N to N 2 by nitrification and denitrification [5,6] .…”

“…Typically, it is characterized by increased nitrogen forms (NH 4 + -N, NO 2 --N and NO 3 --N), phosphates, suspended solids, BOD and COD as well as high populations of the opportunistic pathogen [2,4,5] . If the aquaculture water is untreated, it will result in the emission of nutrient-rich effluents that causes algae blooms, degradation of benthic communities, oxygen depletion and destruction of water quality [4,6] . Current practices for treating aquaculture wastewater include exchange with freshwater, sequencing batch reactors, wetland and filter systems [4,7,8] .…”

Application of activated effective microorganism, mudball and biosand filter for the treatment of dye wastewater

“…A study on EM bacteria (yeast) for high oil-containing wastewater indicated COD removal of more than 94% (Qadir, 2019). The use of EM with sediment aeration for the treatment of aquaculture lake in Baima Lake, Jiangsu, China resulted in the COD value plunging from 14.6 mg/L to 6.2 mg/L over seven months (from hypereutrophic to light eutrophic); the controlled lake without the bioremediation witnessed the COD increment from 41.2 mg/L to 20.9 mg/L (Wang et al, 2019).…”

Effects of organic amendments on soil properties and growth characteristics of Melon (Cucumis melo L.) under saline irrigation

“…Effective microorganisms (EM) contain lactic acid bacteria, yeasts, photosynthetic bacteria, actinomycetes, and other types of organisms [11,15,16] . These microorganisms can secrete beneficial substances such as vitamins and organic acids, thereby creating an environment favorable for plant growth [17] .…”