Treatment Of Rinse Water Research Articles

Copper Recovery from Rinse Waters after Ammoniac Etching of Printed Circuit Boards

The process of sorption-electrochemical cleaning of rinse waters, obtained after ammonia etching of printed circuit boards from copper ions, is proposed. Cation exchanger KU-2×8 and ampholyte Lewatit MonoPlus TP 207 for the extraction of copper were tested. Capacity up to breakthrough of Lewatit MonoPlus TP 207 is 0.11 g/g and a full dynamic exchange capacity for copper of 0.15 g/g. Various options of a pregnant ion exchanger desorption are considered. The best stripping ability has a 20% solution of sulfuric acid. The possibility of desorption by a partially de-coppered eluate was studied. This scheme allows the use of acid formed in the process of copper electro-winning. The effect of concentrations of NH4Cl and NH4OH on the sorption of copper was studied. It was shown that, with an increase in the concentration of NH4Cl to 100 g/dm3, the capacity of the ion exchanger decreases by 10.42%. Thus, the ion exchanger Lewatit MonoPlus TP 207 effectively absorbs copper even at high salt background. A combined sorption-electrochemical technology has been proposed for treatment of rinse waters. The proposed technology will reduce consumption of fresh water and ammonia for printed circuit boards washing and extract copper in the form of elemental metal.

Steel pickling rinse water sludge: Concealed formation of Cr(VI) driven by the enhanced oxidation of nitrite

Steel processing hydroxide sludge (SPHS) is a waste from the treatment of rinse water generated during stainless steel processing. Cr(VI) concentrations of up to 20mg/L were observed in the leachate of a landfill mono-section receiving SPHS. This was surprising since the rinse water is free of Cr(VI) and compliance tests of the fresh SPHS gave no indication of Cr(VI) mobilization. The aim of this study was to identify the processes conducive to the formation of Cr(VI) with emphasis on the effect of H2O2 used in the elimination of NO2−. Rinse water, SPHS, and the landfill leachate were characterized in samples collected over a period of several months. The water treatment process was downscaled to laboratory conditions and the generated SPHS was investigated for Cr(VI) desorption. Results showed that overdosing H2O2 with respect to NO2− caused the formation of Cr(VI) which adsorbed to the SPHS and was only desorbed in presence of a competing anion. This hampers the recognition of the true leaching potential in compliance testing. Therefore, Cr(VI) leaching from the landfill is attributed to patchy zones of deposited SPHS that was generated from process water treatment at overdosed H2O2. In conclusion, Cr(VI) formation may circumvented by an automated process control based on the monitoring of either NO2− or H2O2.

7-2-1 湿式BDF製造機から発生する洗浄廃水のコペルニクス的処理法(7-2 環境対策1,Session 7 環境対策・リサイクル)

7-2-1 湿式BDF製造機から発生する洗浄廃水のコペルニクス的処理法(7-2 環境対策1,Session 7 環境対策・リサイクル)

Design of a fixed-bed ion-exchange process for the treatment of rinse waters generated in the galvanization process using Laminaria hyperborea as natural cation exchanger

In this study, the removal of zinc from galvanization wastewaters was performed in a fixed bed column packed with brown macro-algae Laminaria hyperborea, acting as a natural cation exchanger (resin). The rinse wastewater presents a zinc concentration between 9 and 22 mg/L, a high concentration of light metals (mainly Na and Ca), a high conductivity (0.5–1.5 mS/cm) and a low organic content (DOC = 7–15 mg C/L). The zinc speciation diagram showed that approximately 80% of zinc is in the form of Zn2+ and ≅20% as ZnSO4, considering the effluent matrix. From all operational conditions tested for zinc uptake (17 < bed height<27 cm, 4.5 < flow rate<18.2 BV/h, 0.8 < particle equivalent diameter<2.0 mm), the highest useful capacity (7.1 mg Zn/g algae) was obtained for D/dp = 31, L/D = 11, 9.1 BV/h, τ = 6.4 min, corresponding to a service capacity of 124 BV (endpoint of 2 mg Zn/L). Elution was faster and near to 100% effective using 10 BV of HCl (1 M, 3.0%, 363 g HCl/L of resin), for flow rates higher than 4.5 BV/h. Calcium chloride solution (0.1 M) was selected as the best regenerant, allowing the reuse of the natural resin for more than 3 saturation/elution/regeneration cycles. The best operation conditions were scaled-up and tested in a pre-pilot plant. The scale-up design of the cation exchange process was proposed for the treatment of 2.4 m3/day of galvanization wastewater, resulting in an estimated reactants cost of 2.44 €/m3.

Treatment of rinse water from zinc phosphate coating by batch and continuous electrocoagulation processes

Treatment of spent final rinse water of zinc phosphating from an automotive assembly plant was investigated in an electrochemical cell equipped with aluminum or iron plate electrodes in a batch mode by electrocoagulation (EC). Effects of the process variables such as pH, current density, electrode material and operating time were explored with respect to phosphate and zinc removal efficiencies, electrical energy and electrode consumptions. The optimum operating conditions for removal of phosphate and zinc were current density of 60.0 A/m(2), pH 5.0 and operating time of 25.0 min with Al electrode and current density of 60.0 A/m(2), pH 3.0 and operating time of 15.0 min with Fe electrode, respectively. The highest phosphate and zinc removal efficiencies at optimum conditions were 97.7% and 97.8% for Fe electrode, and 99.8% and 96.7% for Al electrode. The electrode consumptions increased from 0.01 to 0.35 kg electrode/m(3) for Al electrode and from 0.20 to 0.62 kg electrode/m(3) for Fe electrode with increasing current density from 10.0 to 100.0 A/m(2). The energy consumptions were 0.18-11.29 kWh/m(3) for Al electrode and 0.24-8.47 kWh/m(3) for Fe electrode in the same current density range. Removal efficiencies of phosphate and zinc were found to decrease when flow rate was increased from 50 to 400 mL/min in continuous mode of operation. The morphology and elements present in the sludge was also characterized by using SEM and EDX.

STUDY OF COMPETITIVENESS BETWEEN METAL IONS IN SOLUTION IN THE TREATMENT OF SYNTHETIC EFFLUENTS OF PHOSPHATIZATION LINES CONTAINING IRON, NICKEL AND ZINC IONS BY ELECTRODIALYSIS

Using the electrodialysis in treatment of rinsewater, two other solutions are obtained: one concentrated, which can be returned to the galvanic bath; and the other diluted, which has perfect conditions to be reused in a closed circuit as rinsewater. The aim of this work was to evaluate the competitiveness between metallic ions (iron, niquel and zinc) during the electrodialysis technique as a method for treatment of wastewater produced by the phosphatization process. Experiments were conduced with different rinsewater composition and Nafion® 450 and Selemion® AMP membranes. The results obtained show correlation between percentual extractions, current efficiency and the presence of metallic ions in solution.

Ion Exchange Treatment of Rinse Water Generated in the Galvanizing Process

A study was conducted of the viability of using the cationic exchange resins Amberlite IR-120 and Lewatit SP-112 to treat rinse water generated in the galvanizing process as well as acidic wastewater containing zinc (Zn) and iron (Fe). Solutions containing either 100 mg/L of Zn at pH 5.6 (rinse water) or Fe and Zn at concentrations of 320 and 200 mg/L at pH 1.5 (acidic water), respectively, were percolated through packed beds until the resins were exhausted. Breakthrough capacities obtained ranged between 1.1 and 1.5 meq metal/mL resin. The elution of metal and the regeneration of resins were performed with hydrochloric acid. The influence of the flowrate used during the loading stage was also studied, with 0.5 bed volumes/min (3.2 cm/min) found to be the optimum flowrate.

Treatment of Rinsing Water from Bottle Washing Machines by Membrane Filtration with the Objective of Reuse

This paper presents the processes tested for the pretreatment of rinsing water from bottle washing machines, the objective of which is to retain suspended and colloidal organic and inorganic matter in order to prevent membrane scaling and fouling in the downstream reverse osmosis stage. Microfiltration and ultrafiltration as well as two‐layer anthracite/sand filtration proved to be suitable pretreatment processes. The selection of membranes suitable for producing drinking water from rinsing water and the results from the operation of a demonstration plant in a brewery are also dealt with.

Treatment of chromium plating process effluents with ion exchange resins

The surface treatment industry deals with various heavy metals, including the elements Cr, Zn, Ni, Cd, and Cu. Conventional treatments of effluents generate class I solid residue. The aim of this investigation was to study the viability of ion exchange as an alternative process for treatment of rinse water and to determine the efficacy of two ion exchange systems, System 1: “strong” cationic resin–“strong” anionic resin and System 2: “strong” cationic resin–“weak” anionic resin. Commercial resins and solutions taken from rinse tanks of chromium plating companies were used in this investigation. A two-column system, one for the cationic resin and another for the anionic resin, both with 150 ml capacity was mounted. The solution was percolated at a rate of 10 ml/min. The following solutions were used for regeneration of the resins: 2% H 2SO 4 for the cationic and 4% NaOH for the anionic. The percolated solutions revealed chromium contents of less than 0.25 mg/l, independent of the system used. The “strong” cationic resin–“weak” anionic resin gave excellent regeneration results. The “strong” cationic–“strong” anionic resin presented problems during regeneration, and did not release the retained ions after percolation of 2000 ml of 4% NaOH solution. It is concluded that for this type of treatment, the system composed of “strong” cationic resin and “weak” anionic resin is more appropriate.

Abtrennung und Rückgewinnung von Stoffen durch Adsorption und Ionenaustausch

AbstractSeparation and recovery of materials by adsorption and ion exchange. Activated carbons are capable of removing dissolved organics from waste water. They can be used in granular or powdered form, instead of, before, during, or after biological treatment or in water recirculation systems. Usually the adsorbed organics cannot be recovered. Granular activated carbon can be regenerated by thermal reactivation. The use of other adsorbents such as adsorption resins is limited to special cases. Ionic compounds can be removed by ion exchange media. The most common of these are synthetic ion exchange resins. They are used for the treatment of rinse water and pickling effluent. Gold, silver, copper, mercury, chromate, etc. can often be recovered. The degree of separation achieved and the amount of regenerant required – which should be minimized for ecological and economic reasons – depend on process parameters and design.