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Being an internationally accepted standard for the activated sludge modeling, the Activated Sludge Model No.1 (ASM1) was used to simulate the treatment of paper mills effluent in an industrial full-scale sequencing batch reactor (SBR). Key characteristic parameters were estimated and corrected with the wastewater temperature: maximum heterotrophic growth rate μ H (9.69/day), heterotrophic yield Y H (0.625 g cell COD/g COD oxidized) and heterotrophic decay rate b H (1.98/day). The wastewater chemical oxygen demand (COD) was fractionated as slowly biodegradable substrate X S (20%), particulate inert organic matter X I (58%), readily biodegradable substrate S S (18%) and soluble inert organic matter S I (4%). Finally, the SBR operation was simulated with field data from the paper mill. The average relative error of the simulated effluent COD was 12.7%. The results showed that the ASM1 could be reasonably used in the papermaking wastewater treatment simulation. [ABSTRACT FROM AUTHOR]

This paper presents an inclusive approach with focus on energy use and recovery in wastewater management, including wastewater treatment (WWT) and sludge handling. Process data from three Swedish mills and a mathematical model were used to evaluate seven sludge handling strategies. The results indicate that excess energy use in WWT processes counters the potential energy recovery in the sludge handling systems. Energy use in WWT processes is recommended to aim for sufficient effluent treatment, not for sludge reduction. Increased secondary sludge production is favourable from an energy point of view provided it is used as a substrate for heat, biogas or electricity production. [Copyright &y& Elsevier]

This paper compares the long-term data of EOX (Extractable Organic Halogens) determinations in sediments, trichloroguaiacol, i.e. 3,4,5-trichloroguaiacol and 4,5,6-trichloroguaiacol, determinations in the bile of perch (Perca fluviatilis L.) and changes in bottom fauna communities (Pontoporeia affinis L., Mesidotea entomon L., Valvata spp. L.) during 1994–2003. The study area is located at Kemi, on the Gulf of Bothnia, Northern Finland, and is affected by effluent discharged from the pulp and paper mills of Stora Enso Oyj and Oy Metsä-Botnia Ab. The Kemi municipal sewage plant, and River Kemijoki also impose a load in the same area. The main purpose of the study was to assess whether the state of the exposed water ecosystem has improved on the basis of the concentrations of organochlorine compounds in sediment and in perch, due to the modernisation of the wastewater treatment at the mills. In addition, we also investigated whether the changes in the bottom fauna community indicate an improvement in the purification of the effluents. The results indicate that the concentrations of trichloroguaiacols (-1) in perch reflect the decreased discharges of chlorinated substances from the mills. The EOX concentrations in bottom sediments have also decreased to below 50 μ of Cl g-1 in most parts of the study area, which is in good agreement with the reduction in the discharge of organochlorines. According to the long-term changes in bottom fauna, the reduction in the discharge of organochlorine compounds due to modernisation of the pulp mills is reflected in a recovery of the benthic fauna, especially Valvata spp. L. and Pontoporeia affinis L. [ABSTRACT FROM AUTHOR]

A microbial survey of 27 activated sludge (AS) systems included 16 conventional activated sludge (CAS) systems, five sequential batch reactors (SBR) and six oxygen-activated sludge (OAS) systems, all treating pulp and paper effluents. The most prevalent filaments observed were Thiothrix (26%) and Type 021N (22%). The designs of the activated sludge systems seemed to have an effect on the filament types. We found Thiothrix to be the most common filament associated with bulking. For CAS systems, a completely mixed mode of operation promoted Thiothrix and Type 021N growth. Type 021N was favoured in CAS systems with food to microorganism (F/M) ratios higher than 0.2, and with dissolved oxygen (DO) residuals higher than 2 ppm, while Thiothrix generally proliferated at lower F/M ratio and DO residuals. Nutrient deficiencies as well as nutrient dosage variations were suspected in most of the systems having Thiothrix and Type 021N as the most prevalent filaments. Thiothrix appeared to prefer polyphosphate and/or ammonia rather than urea/phosphoric acid as N and P sources. Systems with aerobic selectors showed the lowest filament counts, while systems with no selectors showed the highest filament counts. [ABSTRACT FROM AUTHOR]

An abstract of the article "Phytoremediation technology for wastewater treatment: high rate transpiration system," by Santosh Kumar Yadav and colleagues is presented.