Biotreated Effluent Research Articles

Enhancement of Biotreatment Effluent Quality by Illuminated Titanium Dioxide and Membrane Pretreatment of the Kraft Extraction Waste Stream and by Increased Chlorine Dioxide Substitution

Changes in kraft bioeffluent quality were evaluated as a function of increased chlorine dioxide (ClO2) substitution, and ultrafiltration (UF) membrane and heterogeneous photocatalysis (HP) treatment of extraction (E-stage) wastewater prior to aerobic biological treatment. An increase from 10% to 50% ClO2 substitution in the bleaching of softwood produced a more readily biodegradable waste and an improved bioeffluent quality, especially with respect to toxicity and absorbable organic chloride (AOX). All UF-HP treatments of E-stage wastewater from 10% ClO2 substitution resulted in significant improvements in aerobic bioeffluent with regard to all measured parameters. The best physical/chemical product never corresponded to the best final bioeffluent, indicating some important modification of pollutant biodegradability during the membrane/photocatalysis process. Enhanced treatment of E-stage wastewater from 50% ClO2 substitution also resulted in significant improvements in aerobic bioeffluent with regard to total organic carbon (TOC), chemical oxygen demand (COD), and color, moderate improvement of toxicity, but no substantial reduction in AOX.

Groundwater treatment and aquatic toxicity reduction at a chemical production site

AbstractContaminated groundwater at a chemical antioxidant and phenolic resin chemical production site was subjected to treatability studies to develop design criteria for surface water discharge. Raw groundwater required pretreatment for total suspended solids (TSS) and color removal prior to treatment by ultraviolet light/hydrogen peroxide (UV/H2O2). Because of high capital and operating costs for UV/H2O2, biological treatment was evaluated as an alternate. Respirometric analyses showed that completely mixed activated sludge could be applied as a treatment technology to the groundwater. Biotreatment resulted in an approximately 70 percent reduction in soluble chemical oxygen demand (SCOD). Residual SCOD was recalcitrant to further biodegradation. The treated effluent was tested for aquatic toxicity using fathead minnows (Pimephales promelas) and Ceriodaphnia dubia and was found to be toxic. Toxicity reduction of biotreatment effluent was evaluated in bench‐scale experiments using activated carbon adsorption, filtration, and UV/H2O2. Subsequent toxicity testing showed that filtration alone could reduce the bioeffluent toxicity and that residual SCOD was not the primary source of toxicity.

An appraisal of the effect of biological treatment on the environmental quality of high-yield mechanical pulping effluents

Before biological treatment, the effluents from one CTMP (chemi-thermomechanical pulping) and three TMP (thermomechanical pulping) mills were acutely lethal to fathead minnows ( Pimephales promelas) and the water flea Ceriodaphnia with 48-h LC 50 values of 2.2 to > 50%. The effluents also caused chronic effects at concentrations of 0.01–5.3%. After biological treatment, effluents from the three TMP mills were not acutely lethal to either test species. Biotreated effluents from the CTMP mill were also not acutely lethal to minnows but were lethal to Ceriodaphnia (48-h LC 50: 54–80%). The chronic effects of biotreated effluents occurred at concentrations of 47 to > 100% for fathead minnows and at 5–37% for Ceriodaphnia. Biological treatment also reduced the levels of BOD (>80%), COD (>60%) and wood extractives (>99%).

Factors influencing the effect of bleached kraft mill effluents on drinking water quality

The taste and odour of drinking waters contaminated with bleached kraft mill effluent (BKME) were investigated. Mill effluents with a wide range of odour thresholds were selected and the effects of biological treatment, conventional water purification, carbon filtration, residual chlorine concentration, and recipient water quality were evaluated. No correlation was found between the original odour of BKME and the drinking water impairment. The taste and odour of drinking water prepared from pure glacial-fed river water to which biotreated BKMEs from three separate pulp mills were added was found to be impaired at effluent concentrations ranging from 0.1 to 0.4%. Effluent biotreatment, conventional water purification, and carbon filtration significantly reduced, but did not completely eliminate, BKME-associated taste and odour in potable water samples. The concentration of residual chlorine in the finished drinking water samples was an important factor influencing the degree of taste impairment.

Treating aqueous effluents of the petrochemical industry

The Petrochemical/Ecology Sector Group of the European Council of Chemical Manufacturers Federations estimated the costs of effluent water treatment for a model petrochemical plant which produces 14 petrochemical products with a total output of 671,000 tons/yr. Costs were estimated for a sewer system, a generalized biological treatment system, filtration of biotreated effluent, and activated carbon adsorption. The annual biological treatment costs for the model petrochemical complex were estimated at about 1% of the proceeds. If an activated carbon treatment system had to be added, the annual costs would rise to 2% of the proceeds. These costs represent 10 to 20% of profit, respectively, at a profit margin of 10% on sales, assuming these costs cannot be passed on to the consumer. The reduction of profit will be more severe for a site that is smaller than the model complex because of economies of scale. Flow diagram, tables, and graphs are included.