Oxidation-reduction Potential Control Research Articles

Specific Determination of Inorganic Monochloramine in Chlorinated Wastewaters

The two conventional methods for wastewater chloramination control, residual maintenance and oxidation–reduction potential control, are not specific for the desired disinfectant, monochloramine. Organochloramines, nitrite, manganese, and chromate positively interfere with classical residual control measurements. Oxidation–reduction potential control may not be able to distinguish between monochloramine and weaker disinfecting organochloramines typically found in chlorinated domestic wastewaters. A new method of control is presented that is shown to be specific for the inorganic monochloramine species. The new method is based on a modification of the classical Berthelot analysis method for ammonia. Improvements to the method have greatly increased its selectivity toward monochloramine in chlorinated wastewater matrices. Breakpoint chlorination profiles of various chlorinated wastewaters demonstrate that the conventional control methods could potentially overestimate germicidal efficiency, especially near the breakpoint area. The new method has demonstrated good specificity for monochloramine in the samples studied and has been adapted for automated chlorine control in wastewater.

Application of ORP Control for Nitrogen Removal in Highly Concentrated Activated Sludge Process

A laboratory-scale experiment was carried out for fermentation wastewater treatment by intermittent aeration process using oxidation reduction potential (ORP) as a control parameter. A high concentration of activated sludge was retained in the reactor by ultrafiltration (UF) membrane during the experimental period. For simultaneous carbon and nitrogen removals, the lower and upper ORP limits should be −50 mV and +175 mV respectively. The lower total organic carbon (TOC) and total nitrogen (T-N) concentrations in the effluent was observed, which demonstrated that ORP control method was suitable for high strength fermentation wastewater treatment in a single bioreactor by intermittent aeration process.

Biological denitrification applied to a marine closed aquaculture system

The denitrification of marine effluents was tested using a technology involving immobilized denitrifying bacteria on granular material. To ensure efficient denitrification, an organic carbon addition was needed. The denitrification rate was quantified in the pilot-unit working as a batch fermentor. A first order kinetic model according to the nitrate nitrogen concentration was found and the rate coefficient is an increasing function of the TOC/N(NO − 3) ratio, with an optimum ratio of 1 g g −1. Smaller values led to a nitrite production which was nevertheless oxidized in the treatment line; higher values could lead to the appearance of toxic sulphides. Working on stationary hydraulic loads, the treatment capacity of the unit was about 2.4 kgN(NO − 3) m −3 j −1. It was necessary to wash the packing once every 3 days. The malfunctioning of the unit could be avoided by the oxidation-reduction potential control.

Growth of human lymphoid cells (Raji strain) in a five-liter fermentor.

Procedures used to produce an established line of mammalian cells (L cell) in a New Brunswick fermentor were adapted to propagate human lymphoid cells in suspended culture. Control of pH within defined limits was more effective for regulation of cell metabolism than control of oxidation-reduction potential. An unusually high rate of agitation was required.

Growth of Human Lymphoid Cells (Raji Strain) in a Five-Liter Fermentor

Procedures used to produce an established line of mammalian cells (L cell) in a New Brunswick fermentor were adapted to propagate human lymphoid cells in suspended culture. Control of pH within defined limits was more effective for regulation of cell metabolism than control of oxidation-reduction potential. An unusually high rate of agitation was required.

Controlled pH and oxidation–Reduction potential with a new glass tissue‐culture fermentor

AbstractA 1‐l. fermentor was designed and tested for use as a tissue‐culture vessel. It features a temperature control device, impeller agitation without the necessity of a shaft seal, and a means of measuring, recording, and controlling both pH and oxidation‐reduction potential (ORP). Tests have shown the ORP to change fairly rapidly with impeller speed variations under conditions of a continuous carbon dioxide‐air overlay. Working with strain L mouse fibroblasts (Earle), cell counts of more than 1.25 ×106 ml., without centrifugation and medium renewal, were achieved, and cell counts were maintained above 1 ×106 for more than 30 hr. With the vessel studied, pH control was ±0.05, the ORP control was ±10 mV. Controlled environments for tissue‐cell metabolic studies are entirely feasible with this system.