Treatment Of Toxic Wastewater Research Articles

Development of a new process for treatment of a pharmaceutical wastewater

In this study a process for biological treatment of toxic wastewater from a pharmaceutical company was developed. By simulations on a laboratory scale, the contribution of organic material and toxicity in wastewater from different sources was determined and the degradability of specific compounds were studied. The information obtained from these tests was used to improve the treatability of the wastewater at the sources. As an example a persistent organic phosphorous compound could be degraded after pre-treatment with chemical hydrolysis. By further simulations on a laboratory scale it was possible to screen through a large number of process configurations to determine the best working biological treatment. A combination of fungal and bacterial treatment was found to remove toxicity from the wastewater more than a conventional bacterial treatment. The results from the laboratory studies were confirmed in pilot tests. A full scale treatment plant, which design is based on the results from these studies are presently under construction.

Effect of process variables on the treatment of toxic wastewaters with anaerobic GAC reactors

The expanded-bed anaerobic GAC reactor, operating with GAC replacement, was demonstrated to effectively treat hazardous wastes. This study investigated

Modeling of Toxic Wastewater Treatment by Expanded‐Bed Anaerobic GAC Reactors

The expanded-bed anaerobic GAC reactor, operating with GAC replacement has been demonstrated to treat toxic wastes effectively. The concentration of adsorbable toxic compounds, the hydraulic detention time within the treatment system, and the GAC replacement rate represent three parameters that are strongly related and effectively control process performance. This study investigates the impact of the aforementioned process variables on treatment efficiency. A steady-state model that includes representation of the various phenomena that occur within the anaerobic reactors such as biodegradation, inhibition, competitive adsorption, and attached biomass shearing is presented. Using independently determined adsorption parameters, measured shear loss coefficients, and literature values for biodegradation kinetic parameters, the model predictions are found to be in good agreement with the experimental data.

Toxicity of kraft bleaching effluents on thermophilic and mesophilic VFA methanation

Abstract Kraft mill chlorination (KC) and alkaline extraction (KE) effluents at concentrations higher than 20–46% inhibited methane production from volatile fatty acids (VFA) in batch assays and continuous-flow reactors. Only a KE with an exceptionally low adsorbable organic halogen (AOX) content was non-inhibitory. Also the combined bleach plant mill effluent (BPME) (a mixture of KE and KC) was inhibitory. Anoxic or anaerobic pretreatment, combined with activated-sludge treatment, reduced the methanogenic toxicity of the BPME, while activated-sludge treatment alone increased the methanogenic toxicity. Chemical treatment of the KC using precipitation by CaCl 2 and FeCl 3 as well as oxidation by KMnO 4 only slightly removed the methanogenic toxicity. The methanogenic toxicity of the BPME was less severe in the mesophilic than in the thermophilic continuous-flow process. However, due to conflicting results from the batch assays no general conclusion about the superiority of either the mesophilic or thermophilic process for the treatment of toxic wastewaters could be drawn. In most assays, the replacement of the assay media containing waste-water with VFA showed that the methanogenic toxicity was more bacteriostatic than bactericidal.

Start‐up of sequencing batch reactors for toxic wastewater treatment

Abstract The start‐up of sequencing batch reactors (SBR) for the treatment of phenol‐bearing wastewater was achieved in about a week without any seeding, using the culture present in raw sewage only. The mixed liquor suspended solids (MLSS) concentration was grown to about 3000 mg/1 without showing any inhibition effects at phenol concentrations as high as 800 mg/1. The effluent concentrations of phenol were consistently less than 0.5 mg/1 during most of the start‐up phase. The response of the SBR to shock loadings of phenol at concentrations up to 1600 mg/I was favorable and over 75% phenol removal was maintained at a hydraulic retention time of 1 day.

蛍光Ｘ線法による石炭中硫黄の分析 ＩＩ 硫酸塩硫黄および黄鉄鉱硫黄

Sulfate sulfur and pyritic sulfur in coals are widely analyzed by ISO method. However, it is not adequate for the analyses of many coal samples because of its time-consuming. Therefore, X-ray fluorescence is applied to the determinations of these two sulfur forms to develop the rapid analytical methods. Sulfate sulfur is extracted with dilute hydrochloric acid from coal, precipitated as barium sulfate and determined by measuring the sulfur Kα intensity of barium sulfate collected on membrane filter. Pyritic iron is extracted with dilute nitric acid from the residual coal after the extraction of sulfate sulfur, precipitated as hydroxide or carbamate and determined by measuring the iron Kα intensity of the precipitate collected on membrane filter. Pyritic sulfur is determined by calculating the amount of sulfur associated with pyritic iron. It is noteworthy that reagents of heavy metal compounds are never used for pyritic sulfur analysis by X-ray fluorescence. Accordingly any attention is not necessary to the treatment of toxic waste water containing heavy metal elements except barium.Experiments were carried out with 23 coal samples of various ranks from lignite to anthracite by both X-ray fluorescence and ISO method. Any significant difference is not found between the two methods for both analytical results of sulfate sulfur and pyritic sulfur. The sensitivity limit of X-ray fluorescence method is lower than that of ISO method for each form of sulfur.