Replacement of fresh water use by final effluent recovery in a highly optimized 100% recovered paper mill

Ordóñez, Ruth; Hermosilla, Daphne; Pío, Ignacio San; Blanco, Ángeles

doi:10.2166/wst.2010.933

Cited by 38 publications

(31 citation statements)

References 27 publications

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“…To further reduce water consumption it is therefore necessary to treat and reuse the paper mill effluents. Membrane treatments, such as ultrafiltration (UF) and reverse osmosis (RO) [2,3], allow to produce the water quality required to reuse the effluent. However, effluents from deinking paper mills are characterized by high silica content, ranging from 50 to 250 mg/L as SiO2 [2,4,5].…”

Section: -Introductionmentioning

confidence: 99%

Silica removal with sparingly soluble magnesium compounds. Part I

Latour

Miranda

Blanco

2014

Separation and Purification Technology

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The main bottleneck in the treatment and reuse of effluents from deinking paper mills that employ reverse osmosis (RO) is the high silica content, which causes membrane fouling that limits the recovery of the treatment. Silica removal with magnesium compounds enables to treat large volumes of water with high removal efficiencies at low cost. Although soluble magnesium compounds are efficient, their use is limited since they increase the conductivity in the treated waters. Therefore the use of sparingly soluble magnesium compounds might be a promising alternative. Three sparingly soluble magnesium compounds (MgO, Mg(OH)2 and (MgCO3)4·Mg(OH)2·5H2O) were studied in this paper at three pHs (10.5, 11.0 and 11.5) and five dosages (250-1500 mg/L) at ambient temperature (~20ºC). Only 40% silica removal was obtained, which is not high enough to work at regular RO recoveries without scaling problems. To increase silica removal, the slurries of sparingly soluble compounds were pre-acidified with concentrated sulphuric acid and tested at the same conditions. In this case, high removal rates were obtained (80-86%) at high pH (11.5), even at ambient temperature. These removal rates would allow working at 75-80% recovery in RO units without scaling problems. This pre-acidification, together with the use of Ca(OH)2 as pH regulator limited the increase of the conductivity of the treated waters to only 0.2 mS/cm. Additionally, the use of Ca(OH)2 instead of NaOH as pH regulator increased the chemical oxygen demand removal from 15% to 25%.Keywords: silica removal, magnesium, softening, pre-acidification, membrane, fouling, effluent reuse, paper recycling 2 1.-INTRODUCTIONPaper industry is one of the leading industries in water management and sustainable water use. Although different alternatives have been developed to optimize the use of water in papermaking, there are still some unresolved aspects that limit their implementation at industrial scale. The closure of water loops through the internal reuse of water is limited by the accumulation of contaminants, especially dissolved and colloidal material (DCM), which affects the paper machine runnability and the final product quality [1]. To further reduce water consumption it is therefore necessary to treat and reuse the paper mill effluents. Membrane treatments, such as ultrafiltration (UF) and reverse osmosis (RO) [2,3], allow to produce the water quality required to reuse the effluent. However, effluents from deinking paper mills are characterized by high silica content, ranging from 50 to 250 mg/L as SiO2 [2,4,5]. This makes the removal of silica a key factor for the reuse of the effluent to work on the RO membrane at recoveries higher than 20% [3] without scaling problems. Membrane fouling caused by silica is a bottleneck as silica scaling in RO membranes is severe and, once it is formed, it is very difficult to remove by chemical cleaning [6,7]. This scaling causes decline in water production rates, low permeate quality, unsteady-state operation conditions, higher ener...

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Section: -Introductionmentioning

confidence: 99%

Silica removal with sparingly soluble magnesium compounds. Part I

Latour

Miranda

Blanco

2014

Separation and Purification Technology

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“…An anionic polyacrylamide with high molecular weight and medium charge density was used as flocculant aid in all tests (supplied by SERTEC-20 S.L., Spain). Two different pH regulators were used: NaOH and Ca(OH) 2 , both of analytical grade supplied by PANREAC. Coagulants were prepared at 20 wt%, flocculant at 0.1 wt% and pH regulator at 10 wt% with ultrapure water on a daily basis.…”

Section: -Materials and Methodsmentioning

confidence: 99%

“…Sustainable water use in the paper industry requires the closure of the water system without affecting paper machine runnability and product quality [1], which can be achieved by reusing the mill effluent after its advanced membrane treatment [2] and/or by the use of reclaimed water [3], depending on the availability of alternative water sources.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, causing a decline in water production rates, low permeate quality, unsteady-state operation conditions, higher energy consumption and serious damages on the membranes that shorten their lifetime, by doing so compromising the technical and economic feasibility of the whole treatment chain. If silica is not removed the RO recovery is of only around 20% [2].…”

Section: Introductionmentioning

confidence: 99%

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Silica removal from newsprint mill effluents with aluminum salts

Latour

Miranda

Blanco

2013

Chemical Engineering Journal

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The main obstacle for the implementation of reverse osmosis (RO) in a treatment chain to reuse the effluent of a newsprint mill as fresh water is the high silica content of the water, which produces severe scaling on the membrane, thus, limiting its recovery. Coagulation is one of the preferred methods to reduce silica concentration. Five aluminum based coagulants have been tested at five dosages (500-2500 ppm) and three pHs (8.3, 9.5 and 10.5). All products showed their best efficiency at the highest dosage and pH, with the exception of alum, that was more efficient at intermediate dosages. A combination of a polyaluminum nitrate sulphate with a cationic quaternary polyamine (PANS-PA2), was the most efficient and versatile coagulant. It removed 97% of silica (5 ppm residual silica) at the optimal conditions (pH 10.5, 2500 ppm) and it was very efficient (76% silica removal) at pH 8.3, avoiding the need of any pH adjustment, and minimizing the conductivity and pH increase of the treated waters as well as obtaining some removal of the organic colloidal matter (≈25%).

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“…Soluble biodegradable organic compounds may efficiently be removed by combinations of anaerobic and aerobic processes (Ordóñez et al 2010), but these treatments do not prevent the accumulation of the non-biodegradable organic chemical fraction (Ahmad et al 2007;Habets and Knelissen 1997), such as high molecular weight organics (>1000 Da) (Yeber et al 2007), lignin and lignin-derived compounds (Chang et al 2004;Dahlman et al 1995;Eriksson and Kolar 1985;Thompson et al 2001), toxic chlorinated organics (Balcioglu et al 2007), and pollutants with sulfonic groups (Beltrán et al 2000;Masuyama et al 2000), among others. These chemicals usually produce alterations in the activity of biological reactors (Habets and Knelissen 1997).…”

Section: Introductionmentioning

confidence: 99%

The application of advanced oxidation technologies to the treatment of effluents from the pulp and paper industry: a review

Hermosilla

Merayo

Gascó

et al. 2014

Environ Sci Pollut Res

152

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Paper industry is adopting zero liquid effluent technologies to reduce fresh water use and meet environmental regulations, which implies water circuits closure and the progressive accumulation of pollutants that must be removed before water re-use and final wastewater discharge. The traditional water treatment technologies that are used in paper mills (such as dissolve air flotation or biological treatment) are not able to remove recalcitrant contaminants. Therefore, advanced water treatment technologies, such as advanced oxidation processes (AOPs), are being included in industrial wastewater treatment chains aiming to either improve water biodegradability or its final quality. A deep review of the current state of the art regarding the use of AOPs for the treatment of the organic load of effluents from the paper industry is herein addressed considering mature and emerging treatments for a sustainable water use in this sector. Wastewater composition, which is highly dependent of the raw materials being used in the mills, the selected AOP itself, and its combination with other technologies, will determine the viability of the treatment. In general, all AOPs have been reported to achieve good organics removal efficiencies (COD removal >40%; and about an extra 20% if AOPs are combined with biological stages). Particularly, ozonation has been the most extensively reported and successfully implemented AOP at an industrial scale for effluent treatment or reuse within pulp and paper mills; although Fenton processes (photo-Fenton particularly) have actually addressed better oxidative results (COD removal ≈65-75%) at lab scale, but still need further development at large scale.

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Replacement of fresh water use by final effluent recovery in a highly optimized 100% recovered paper mill

Cited by 38 publications

References 27 publications

Silica removal with sparingly soluble magnesium compounds. Part I

Silica removal with sparingly soluble magnesium compounds. Part I

Silica removal from newsprint mill effluents with aluminum salts

The application of advanced oxidation technologies to the treatment of effluents from the pulp and paper industry: a review

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