Risk of Pesticides Mixtures in Rice to Birds and Humans in Iran.

Rice is a staple in the diet of nearly half of the world's population. As with most crops, pesticides are used as a tool to increase crop yield in rice farming. This study investigated the residues of 14 organophosphate insecticides and 2 herbicides in rice cultivated at five locations in the southwest of Iran. The pesticide residues were then used to estimate the risk that they may pose to the health of bird and human consumers. The rice samples from the five locations contained residues from 10 to 13 pesticides. Of the 16 pesticides measured, the mean concentration of 12 pesticides exceeded the maximum residue limit set by the Iranian National Standards Organization at two or more of the sampling sites. The greatest total exceedance (sum of all pesticides detected in rice) of the species sensitivity distributions constructed for birds was 0.74% and the level of concern set for the assessment was an exceedance ≥ 5%, which suggests a relatively low risk to birds. For human consumers, no single pesticide measured in rice samples posed a considerable risk. However, when considering the mixture of pesticides present in rice samples, the cumulative risk exceeded the level of concern in all samples from all sites. The margin of safety for the mixture of pesticides present in rice samples ranged from 5.8 to 29.1, with 1 being the level of concern. The results of this study indicate that efforts need to be made to mitigate the exposure of human consumers to pesticides present in rice cultivated in Iran. This study also highlights the need to collect data on pesticides residues in other crop cultivated in Iran.

Role of bio-electrochemical technology for enzyme activity stimulation in high-consumption pharmaceuticals biodegradation.

Active pharmaceutical ingredients (APIs) and their intermediate residues have recently been considered a serious concern. Among technologies, bio-electrochemical technologies (BETs) have stimulated the production of bio-electrical energy. This review aims to examine the benefit and mechanism of BETs on the degradation of high-consumption pharmaceutical compounds, including antibiotic, anti-inflammatory, and analgesic drugs, and the stimulation of enzymes induced in a bioreactor. Moreover, intermediates and the proposed pathways of pharmaceutical compound biodegradation in BETs are to be explained in this review. According to studies performed exclusively, the benefit of BETs is using bio-electroactive microbes to mineralize recalcitrant pharmaceutical contaminants by promoting enzyme activity and energy. Since BETs use the electron transfer chain between bio-anode/-cathode and pharmaceuticals, the enzyme activity is essential in the oxidation and reduction of phenolic rings of drugs and the ineffective detoxification of effluent from the treatment plant. This study is suggested a vital and influential role of BETs in mineralizing and enzyme induction in bioreactors. Eventually, a content of future developments or outlooks of BETs are propounded to improve the pharmaceutical industries' wastewater problems.

Removal of aspirin from aqueous solution using electroactive bacteria induced by alternating current.

This study aims to improve bacterial laccase enzyme activity (LEA) and dehydrogenase activity (DHA) affecting acetylsalicylic acid (ASA) biodegradation using an alternating current (AC). A microbial consortium was inoculated in an electroactive bioreactor supplied with an AC by a function generator under operating conditions of amplitude (AMPL) = 2-10 peak-to-peak voltage (Vpp), optical fiber splice tray (OFST) = 0.1 V, and sine wave frequency = 10 Hz. The obtained results revealed that at an applied voltage of 8 Vpp and an OFST of 0.1 for 12 h, the maximum bacterial LEA and DHA were 30.6 U/mL and 75.5 micro grTF/cm2.gr biomass; respectively. Cell viability and permeability were equal to 95.7% and 0.3%; respectively, at the voltage of 8 Vpp. Moreover, liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analyses showed that by-products had lower intensity at 8 Vpp compared with that of 2 Vpp voltage. Finally, the results demonstrated an optimum applied voltage of the AC, which could stimulate and promote bacterial LEA and DHA. Therefore, an electroactive bioreactor supplied with an AC can be a novel system for stimulation of enzyme activities in the process of ASA biodegradation.

Minimization of hazardous sludge production using a bioelectrochemical system supplied by an alternating current electric field.

In the present study, minimization of hazardous bio-sludge production was investigated using a bioelectrochemical system supplied by an alternating current electric field and supplemented with phenol as a cabon source. The experiments were conducted in an air-conditioned bioreactor and at neutral pH value. Moreover, steel wool and carbon cloth were utilized as electrodes in the bioelectrochemical system. The experiments were operated in an air-conditioned bioreactor at 25 ℃ and a neutral pH value with carbon to nitrogen (C/N) ratio of 0.5-6. The results obtainedshowed that complete phenol electro-biodegradation occurred at a C/N ratio ofa frequency of 5 Hz, and 0.4 peak-to-peak voltage (Vpp) over 2 h.Besides, sludge production and sludge yield were obtained at the C/N ratio of 0.5-6 by 200-382 mg VSS/g COD and 82-89.4 mg TSS/g COD, respectively. Ultimately, the C/N ratio of 1 seemed to be optimum for microbial growth with the phenol biodegradation efficiency of 99.9% as well as the lowest sludge production. These results demonstrated that the proposed bioelectrochemical system supplied by low-frequency and low-voltage electric current could reduce hazardous sludge production.

Microbial electrochemical system for the phenol degradation using alternating current: Metabolic pathway study.

The present study was conducted to investigate the effect of alternating current (AC) on phenol removal in a microbial electrochemical system (MES) and determine its by-products. The bioreactor used for this purpose operates in the batch mode supplied with an AC power supply. The factors stimulating this process including frequency, applied voltage, duty cycle, carbon to nitrogen ratio, and the initial phenol concentration were investigated. The optimum operating conditions of the bioreactor were obtained at 5 Hz frequency, 0.4 peak-to-peak voltage (Vpp), C0 = 100 mg.L-1 phenol, pH = 7, C/N = 1, and the sine wave. Phenol was completely degraded under the optimum operating conditions for 2 h. The GC-MS analysis showed the presence of carboxylic acid, oxalic acid, and propionic acid. It was observed that the generated by-products are non-toxic and phenol is completely removed to nontoxic compounds. The results show that under optimum conditions, using an alternating current, the proposed system generated low-hazard byproducts with a low energy consumption.

Metabolic activity and pathway study of aspirin biodegradation using a microbial electrochemical system supplied by an alternating current.

The main aim of this study is to investigate the biodegradation of highly concentrated aspirin as an emerging pollutant from aqueous solution using an alternating current microbial electrochemical system. A single-chamber Plexiglas cylindrical reactor equipped with stainless steel mesh electrodes (18 cm height × 16 cm diameter) was applied as the bioreactor in batch mode with an effective volume of 5 L, height of 20 cm, and the diameter about 20 cm by AMPL = 2 Vpp, OFST = 0.1 V, waveform = sinusoidal, frequency = 10 Hz, and pH = 7. The process parameters including initial concentration (100-400 mg L-1), chemical oxygen demand (COD), activity of enzymes, biokinetic and pathway studies at very low voltage and very low frequency alternating current were investigated. The specific biodegradation rate of aspirin was calculated based on Michaelis-Menten model. The complete aspirin removal efficiency and the maximum enzymatic activity were achieved at 250 mg L-1 aspirin, voltage of 2 Vpp and applied current = 3 mA during 6 h. The bioassay of aspirin concentrations in biofilm of the system using flow cytometry analysis resulted in the live and necrotic cells shares of 96.2%, and 0.44%, respectively. Moreover, the LC and GC-MS analysis showed low molecular weight acids such as oxalic and acetic acid at 6 h time under the optimal conditions using very low applied voltage and frequency. Obtaining low reaction time for degradation, high potential in biodegradation, oxidation and mineralization ability were the novelty of treatment system with high concentration aspirin in the study.