This study examined the ability of activated sludge (AS) to sorb and biodegrade ethylmethylphosphonic acid (EMPA) and malathion, a degradation product and surrogate, respectively, for an organophosphate chemical warfare agent. Sorption equilibrium isotherm experiments indicate that sorption of EMPA and malathion to AS is negligible. EMPA at a concentration of 1 mg L(-1) degraded by approximately 30% with apparent first-order kinetics, possibly via co-metabolism from nitrification. Heterotrophic bacteria and abiotic mechanisms, however, are largely responsible for malathion degradation also with apparent first-order kinetics. EMPA did not inhibit chemical oxygen demand (COD) oxidation or nitrification activity, although malathion did appear to induce a stress response resulting in inhibition of COD oxidation. The study also included a 30-day experiment in which malathion, at a concentration of 5 mg L(-1), was repeatedly fed to AS in bench-scale sequencing batch reactors (SBRs) operating at different solids retention times (SRTs). Peak malathion concentrations occurred at day 4.5, with the longer SRTs yielding greater peak malathion concentrations. The AS reduced the malathion concentrations to nearly zero by day 10 for all SRTs, even when the malathion concentration in the influent increased to 20.8 mg L(-1). The data suggest a biodegradation pathway for malathion involving an oxygenase. Phylogenetic analyses revealed that all samples had an abundance of Zoogloea, though there was greater bacterial diversity in the SBR with the SRT of 50 days. The SBR with an SRT of 9.5 days had an apparent reduction in the diversity of the bacterial community.

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2014.03.031DOI Listing

Publication Analysis

Top Keywords

malathion concentrations
12
malathion
10
activated sludge
8
solids retention
8
retention times
8
empa malathion
8
malathion degradation
8
apparent first-order
8
first-order kinetics
8
cod oxidation
8

Similar Publications

Poly(ionic liquid)-regulated green one-pot synthesis of Au@Pt porous nanospheres for the smart detection of acid phosphatase and organophosphorus inhibitor.

Talanta

January 2025

State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Engineering Research Center of Technical Textiles, Ministry of Education, College of Materials Science and Engineering, College of Science in Donghua University, State Key Laboratory of Polyolefins and Catalysis, Shanghai Key Laboratory of Catalysis Technology for Polyolefins (Shanghai Research Institute of Chemical Industry Co., Ltd., Shanghai), Key Laboratory of High Performance Fibers & Products, PR China. Electronic address:

Here, a green poly(ionic liquid)-regulated one-pot method is developed for the synthesis of Au@Pt core-shell nanospheres (PNSs) under mild reaction conditions in water. It is found that the poly(ionic liquid) poly[1-methyl-3-butyl (3-hydroxy) imidazole] chloride (PIL-Cl) is very vital to guide the construction of Au@Pt PNSs. The as-obtained Au@Pt-1 PNSs have perfect spherical outlines, porous core-shell structures and large specific surface area by which they exhibit excellent peroxidase-like activity in acidic media and can be used to develop a simple and reliable colorimetric sensing platform.

View Article and Find Full Text PDF

Impact of land covers on pesticide contamination and the associated ecological risk in a major tributary of the Pearl River, South China.

Sci Total Environ

December 2024

The Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, China. Electronic address:

Pesticide contamination in the river basins is closely associated with land covers. However, the impact of land covers on the pesticide contamination remains unclear. In this study, concentrations of 14 pesticides (10 insecticides, 3 fungicides, and 1 herbicide) in water were investigated along a major tributary of the Pearl River in wet and dry seasons in 2023.

View Article and Find Full Text PDF

The concentration of selected organophosphorus pesticides associated with PM10 in agricultural ambient air in Iran: Health risk assessment using Monte Carlo simulation.

Ecotoxicol Environ Saf

December 2024

Research Center for Health Sciences, Institue of Health, Department of Environmental Health Engineering, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran. Electronic address:

Organophosphate pesticides, widely utilized for pest management globally, are associated with various adverse health effects upon exposure. This study aimed to investigate the presence of organophosphate pesticides in particulate matter (PM10) and evaluate the potential risks to human health using both deterministic and probabilistic approaches in urban and suburban areas of Yasuj City, Iran. A total of 32 air samples were collected during the study period.

View Article and Find Full Text PDF

Removal of Pesticides from Lemon and Vegetables Using Electrolyzed Water Kitchen Devices.

Molecules

December 2024

Department of Food Analysis and Environmental Protection, Faculty of Chemical Technology and Engineering, Bydgoszcz University of Science and Technology, Seminaryjna 3, 85-326 Bydgoszcz, Poland.

The possibility of using kitchen electrolyzed water devices (EWDs) for removing residual concentrations of pesticides (malathion, fenitrothion, and p,p'-DDT) from lemon, cucumber, and carrot surfaces was tested. Three commercial devices with different parameters were tested, and their effectiveness was compared with traditional washing methods using water. Based on the results, it was found that by using EWDs, the best removal of water-soluble pesticides was achieved with malathion and fenitrothion (reduction of up to 80%).

View Article and Find Full Text PDF

Esterase-2 mutant-based nanostructured amperometric biosensors for the selective determination of paraoxon (Neurotoxin).

Anal Biochem

December 2024

Biosensors Research Lab, Zewail City of Science and Technology, 6th October City, Giza, 12578, Egypt; Applied Organic Chemistry Department, National Research Centre (NRC), Dokki, Giza, 2622, Egypt. Electronic address:

Organophosphate pesticides (OPs) are causing non-selective inhibition in enzymatic bioreceptors, thus the enzymatic-inhibition-based traditional assays are not suitable for their specific detection in food and environmental samples. Accordingly, a selective nanostructured electrochemical biosensing system was designed using six mutants of the esterase-2 (EST2 protein) enzymes from A. acidocaldarius to be exploited as targeting bio-receptors for the specific detection of OPs.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!