RESUMEN
Based on the requirement of National Implementation Plan for the Stockholm Convention on Persistent Organic Pollutants (NIP), six industries including pulp and paper industry have been set as the priority key sectors to implement the best available technology and best environmental practice (BAT/BEP) within a specific time for UPOPs reduction. Non-wood pulping has always played important role in virgin pulp production in China, its elemental chlorinated bleaching process has been confirmed as main source of Dioxin emission for the sector. As the signature party of Stockholm Convention and long time existing country of non-wood pulping, identification of Dioxin emission situation is significant importance to China to committee the obligation of Stockholm Convention. The Dioxin concentrations in outflow water of bamboo, straw, reed, and bagasse pulping processes (chlorination alkaline extraction hypochlorite, CEH) are 41.8 pg x L(-1), 72.7 pg x L(-1), 7.46 pg x L(-1), and 19.7 pg x L(-1) respectively, which are all around the national waste water discharge standard (30 pg x L(-1)). But relevant data will easily exceed national standard while the limitation of unit water consumption for pulp making is decreased. So the application of best available techniques/best environmental practices (BAT/BEP) is very necessary to improve relevant mills up to the above standard, and proceed the sector meeting the national and international requirements for Dioxin emission. At the same time, the text calculates emission factors on bamboo, straw, reed and bagasse pulp making process through whole process monitoring, which will provide meaningful reference for increasing relevant factors in UNEP Toolkit.
Asunto(s)
Dioxinas/análisis , Monitoreo del Ambiente , Contaminantes Ambientales/análisis , Residuos Industriales/análisis , Papel , China , Sasa/químicaRESUMEN
Micellar-enhanced ultrafiltration (MEUF) was used to remove phenol from simulant aqueous solutions. The effect of groups difference of cationic surfactant on the solubilization of phenol was investigated through orthogonal experiment, namely, surfactants with the same length of hydrocarbon chain but different hydrophilic head group and vice versa. The effects on the solubilization of phenol of various operating parameters in the practical application of MEUF with OTAB were studied, including surfactant concentration, electrolyte concentration, feed phenol concentration, operating pressure, temperature, respectively. The results showed that the rejection of phenol increased in the order as follows: cetyltrimethylammonium bromide (CTAB)Asunto(s)
Fenoles/química
, Tensoactivos/química
, Ultrafiltración/métodos
, Alcanos/química
, Carbonatos/química
, Cetrimonio
, Compuestos de Cetrimonio/química
, Cetilpiridinio/química
, Electrólitos
, Membranas Artificiales
, Micelas
, Potasio/química
, Presión
, Compuestos de Amonio Cuaternario/química
, Soluciones
, Temperatura
, Agua/química
RESUMEN
The retentate stream containing Cd2+ was chosen for the investigation. Effects of acid reagent, chelator, pH and operation mode on separation of Cd2+ and recovery of SDS, as well as efficiency of reclaimed SDS were investigated. The optimum conditions in acidification were obtained: H2SO4 as acid reagent, pH = 1.0, operation mode of batch. Under these conditions, separation of Cd2+ and recovery of SDS are 98.0% and 58.1%, respectively. And the efficiency of reclaimed SDS for removing Cd2+ is 80.2%. In chelation, the optimum conditions were investigated: EDTA as chelator, uncontrolled pH (pH = 4.4) and operation mode of batch. Under these conditions, separation of Cd2+ and recovery of SDS are 90.1% and 60.5%, respectively. And the efficiency of reclaimed SDS for removing Cd2+ is 79.4%.
Asunto(s)
Cadmio/química , Dodecil Sulfato de Sodio/química , Tensoactivos/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Quelantes/química , Ácidos Sulfúricos/química , Ultrafiltración/métodosRESUMEN
Micellar enhanced ultrafiltration (MEUF) is a new method which is based on the surfactant of the unique characteristic of parental molecular structure that can remove heavy metals in the water. The concentrated solution by dealing with the MEUF contains high concentration of heavy metal ions, so it must be need for further processing. The electrolysis method was employed to recovery Cd2+ from the concentrated solution of micellar enhanced ultrafiltration (MEUF). Effects of type of electrode, electrolysis voltage (U) and time (t), solution pH, surfactant to Cd2+ molar ratio ([SDS]/[Cd2+]) on Cd2+ recovery efficiency were investigated. The study found that the surfactant had some effect of resistance to electrolysis process. The optimum experimental conditions were obtained: stainless steel (anode)-graphite (cathode), U = 2.8 V, t = 100 min, pH = 4, [SDS]/[Cd2+] = 5 ([SDS] = 8.5 mmol/L constant). And the recovery efficiency of Cd2+ in the concentrated solution was 50.26%.
Asunto(s)
Cadmio/aislamiento & purificación , Tensoactivos/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/aislamiento & purificación , Cadmio/química , Electrólisis , Ultrafiltración/métodos , Contaminantes Químicos del Agua/químicaRESUMEN
The purpose of this study was to investigate the use of foam fractionation to recover valuable surfactant (SDS) and metal ion (Cd2+) in the permeate of micellar-enhanced ultrafiltration (MEUF). The effects of operating factors, such as time, air flow rate, feed flow rate, liquid height, foam height, feed surfactant concentration, ethanol concentration and temperature on separation characteristics were studied in the continuous operation. When the concentrations of surfactant (SDS) and metal ion (Cd2+) in the feed solution were 500 mg/L and 10 mg/L, an enrichment ratio of 3.1 was achieved for SDS along with 52% removal fraction, as well as 99.35% Cd2+ was removed, after optimization of different process parameters. As the optimized results, the air and liquid flow rates were 100 L/h and 5 L/h, liquid and foam heights were 45 cm and 66 cm, respectively, sparger pore size was 10 microm. The Cd2+ concentration in the effluent was lower than 0.1mg/L which could meet the integrated wastewater discharge standard (the first grade of national discharge standards in China).