Effect of organic loading rate on the removal of DMF, MC and IPA by a pilot-scale AnMBR for treating chemical synthesis-based antibiotic solvent wastewater.

This study focuses on the effects of organic loading rate (OLR) on the removal of N,N-Dimethylformamide(DMF), m-Cresol (MC) and isopropyl alcohol (IPA) by a pilot-scale anaerobic membrane bioreactor (AnMBR) for treating chemical synthesis-based antibiotic solvent wastewater at period of improved influent COD concentration with decreased HRT. The whole process was divided into five stages in terms of the variation of OLR ranging from 3.9 to 12.7 kg COD/(m3·d). During 249 days of operating time, the average DMF, MC, IPA removal efficiency were 96.9%,98.2% and 96.4%, respectively. Cake layer was accumulated on the membrane surface acted as a dynamic secondary biofilm which lead to the increase of physical removal rate. In addition, mathematical statistical models was built on the linear regression techniques for exploring the inner relationship between EPS and the performance of the AnMBR.

Poly(glyceryl monomethacrylate-co-ethylene glycol dimethacrylate) monolithic columns with incorporated bare and surface modified gluconamide fumed silica nanoparticles for hydrophilic interaction capillary electrochromatography.

This research article presents the preparation and characterization of monolithic capillary columns with incorporated bare fumed silica nanoparticles (FSNPs) and surface coated gluconamide FSNPs and their subsequent use in hydrophilic interaction capillary electrochromatography (HI-CEC) of small relatively polar solutes. The monolithic support was based on the in situ polymerization of glyceryl monomethacrylate (GMM) and ethylene glycol dimethacrylate (EDMA) yielding the poly(GMM-co-EDMA) monolith for the incorporation of bare and gluconamide-FNSPs. The poly(GMM-co-EDMA) monolith functioned as a true "support" for both types of polar FSNPs "stationary phases". In other words, monolithic capillary columns with "FSNPs stationary phases" were obtained in the sense that the contribution of the monolith proper to solute' retention was at its minimum. The gluconamide-FSNPs were obtained by reacting the FSNPs with the polar organosilane N-(3-triethoxysilylpropyl)gluconamide either by a pre- or on-column approach yielding p-gluconamide-FSNPs or o-gluconamide-FSNPs, respectively. While the p-gluconamide-FSNPs was coated by an oligosiloxane gluconamide layer as revealed by thermogravimetric analysis, the o-gluconamide-FSNPs are thought to be covered with a monomeric layer of gluconamide ligands as was manifested by the higher plate number obtained on the latter than on the former gluconamide-FSNPs incorporated monolithic columns. In the on-column modification process of FSNPs, the reaction was performed in a closed system whereby atmospheric water vapor are not available to cause the polymerization of the trifunctional organosilane N-(3-triethoxysilylpropyl)gluconamide. Also, the fact that the o-gluconamide-FSNPs incorporated monoliths were made from bare-FSNPs incorporated monoliths may indicate that the bare FSNPs were better dispersed into the monolithic matrix than the p-gluconamide-FSNPs, a condition that might have further contributed to the lower plate count obtained on p-gluconamide- than o-gluconamide-FSNPs incorporated monolithic columns. Overall, o-gluconamide-FSNPs stationary phases and to a lesser extent bare-FSNPs stationary phases proved useful in HI-CEC of small polar solutes, including DMF, formamide, thiourea, some phenols and nucleobases.

An Eco-tank system containing microbes and different aquatic plant species for the bioremediation of N,N-dimethylformamide polluted river waters.

An Eco-tank system of 10m was designed to simulate the natural river. It consisted of five tanks sequentially connected containing microbes, biofilm carriers and four species of floating aquatic plants. The purification performance of the system for N,N-dimethylformamide (DMF) polluted river water was evaluated by operating in continuous mode. DMF was completely removed in Tanks 1 and 2 at influent DMF concentrations between 75.42 and 161.05mg L-1. The NH4+-N concentration increased in Tank 1, followed by a gradual decrease in Tanks 2-5. Removal of NH4+-N was enhanced by aeration. The average effluent NH4+-N concentration of Tank 5 decreased to a minimum of 0.89mg L-1, corresponding to a decrease of 84.8% when compared with that before aeration. TN concentration did not decrease significantly as expected after inoculation with denitrifying bacteria. The average effluent TN concentration of the system was determined to be 4.58mg L-1, still unable to satisfy the Class V standard for surface water environmental quality. The results of this study demonstrated that the Eco-tank system is an efficient process in removing DMF, TOC, and NH4+-N from DMF polluted river water. However, if possible, alternative technologies should be adopted for controlling the effluent TN concentration.

A novel chemical/biological combined technique for N, N-dimethylformamide wastewater treatment.

N, N-Dimethylformamide (DMF) is a widely used organic solvent whose wastewater is difficult to biodegrade directly. In this paper, a novel chemical/biological combined technique consisting of alkaline hydrolysis stripping, activated sludge and a bio-trickling filter (BTF) was developed for DMF wastewater treatment. The main pollutant, DMF, was decomposed to dimethylamine and formate under alkaline conditions, and the dimethylamine was stripped out by the BTF. The pretreated wastewater was then degraded in an activated sludge process. The operation performances of alkaline hydrolysis, activated sludge and BTF processes were investigated separately. At the optimal conditions of an alkali dosage of 40 g/L, an air/liquid ratio of 3000:1 and 5 h in the air-stripping process, the removal of total organic carbon and DMF was found to be 58% and 96%, respectively. A chemical oxygen demand removal efficiency of 80-90% was obtained in the activated sludge process. The performance of BTF was excellent with a dimethylamine removal efficiency close to 90% even at a high loading of 16 g/d.

Analysis of metabolites of N,N-dimethylformamide in urine samples.

AIM: To assess the suitability of different methods for biological monitoring of internal dose to N,N-dimethylformamide (DMF) in occupational settings. METHODS: The determination of urinary metabolites of DMF, N-hydroxymethyl- N-methylformamide (HMMF), N-methylformamide (NMF) and N-acetyl- S-(N-methylcarbamoyl) cysteine (AMCC) was carried out by four selected analytical procedures. Two methods solely measured total NMF (HMMF and NMF). The other two methods measured both total NMF and AMCC in one analytical run. All four methods were tested on 34 urine samples from workers exposed to DMF. RESULTS: Comparison of the four methods for determination of total NMF in urine showed that results were similar for three methods, while the remaining one provided NMF levels significantly lower (by 22%) than the other methods. Thus, all but one of the tested methods for the determination of total NMF can be considered to be suitable for biological monitoring of internal dose to DMF. The two tested methods for the determination of AMCC afforded results that showed high correlation but differed significantly (by 10%). CONCLUSION: The choice of the biomonitoring method depends mainly on the purpose for which the measurement is conducted. For evaluation of acute exposures or to assess safety measures in the working area, an updated version of the traditional method of Kimmerle and Eben (1975a, b) for the determination of total NMF in urine is sufficient. For risk assessment after exposure to DMF, the determination of AMCC should be carried out, since AMCC, but not total NMF, is supposed to be related to the toxicity of DMF. However, there is still a need to develop an easier, more sensitive and more selective method for the determination of AMCC in urine until AMCC can be considered for regulatory purposes in occupational settings.