Giuseppe Mazziotti di Celso

Wastewater reuse by means of UF membrane process: a comparison with Italian provisions

Abstract Membrane filtration can represent a valid solution to water scarcity. In this paper, a study has been carried out about water reuse aimed to industrial and agricultural purposes, starting from a real wastewater coming from Ponte Rosarolo plant located in the Centre of Italy. Wastewater has been treated by means of ultrafiltration membrane process. Results obtained have shown that permeate flux meets provisions in terms of drain water species concentration stated by Italian regulation (D.Lgs 152/99), but there are still unsolved problems as for water reuse limits (D.M. 15/2003): particularly, a final disinfection stage seems to be necessary to lower the value of coliforms content to 0.

On the removal of natural organic matter from superficial water by using UF and MF membranes

Excessive chlorine usage in surface water disinfection may constitute a problem, since residual chlorine reacts with natural organic matter (NOM), already present in surface water, giving birth to disinfection by-products (DBPs). Aim of the work was to experimentally test the feasibility of a disinfection process by combining chlorination and ultrafiltration (UF), thus minimizing chlorine dosage. At the scope, in this paper, the removal of humic acid (aldrich humic acid, AHA), representative of NOM, has been studied by using tubular UF and microfiltration (MF) membranes (50 nm, 20 nm, 0.2 μm). Results show that, regarding AHA rejection and turbidity, investigated membranes are not influenced by transmembrane pressure and AHA concentration, while UF membranes seem to be more effective in salt separation. Anyway, both UF and MF show a removal efficiency up to 90%. Moreover, a process scheme aimed at water use/reuse is proposed, in which the chlorination step is substituted by a double filtration step (UF followed by reverse osmosis), in order to obtain high quality water, usable also for industrial purposes in which a high purity water is needed.

Removal of tetramethyl ammonium hydroxide from synthetic liquid wastes of electronic industry through micellar enhanced ultrafiltration

ABSTRACT In this paper, the separation of tetramethyl ammonium hydroxide (TMAH) from synthetic liquid wastes of electronic industry is carried out by using a micellar enhanced ultrafiltration (MEUF) process. This treatment represents the first step of an integrated process, aimed at the recovery of TMAH and surfactant and water reuse. The laboratory tests are carried out with an ultrafiltration module using initial solutions having a concentration of pollutant equal to 2 g/L and by adding sodium dodecyl sulfate as a surfactant, at a concentration in the range 4–10 mM/L, that is, under and above its critical micellar concentration (CMC). The experiments have been carried out at a fixed temperature of 25°C. The obtained results showed that very good percentage removals of TMAH are achieved (99%), especially when the surfactant was above the CMC. GRAPHICAL ABSTRACT

Purification of residual leach liquors from hydrometallurgical process of NiMH spent batteries through micellar enhanced ultra filtration

Hydrometallurgical processes for the treatment and recovery of metals from waste electrical and electronic equipment produce wastewaters containing heavy metals. These residual solutions cannot be discharged into the sewer without an appropriate treatment. Specific wastewater treatments integrated with the hydrometallurgical processes ensure a sustainable recycling loops of the electrical wastes to maximize the metals recovery and minimize the amount of wastes and wastewaters produced. In this research activity the efficiency of ultrafiltration combined with surfactant micelles (micellar-enhanced ultrafiltration) was tested to remove metals form leach liquors obtained after leaching of NiMH spent batteries. In the micellar-enhanced ultrafiltration, a surfactant is added into the aqueous stream containing contaminants or solute above its critical micelle concentration. When the surfactant concentration exceeding this critical value, the surfactant monomers will assemble and aggregate to form micelles having diameter larger than the pore diameter of ultrafiltration membrane. Micelles containing contaminants whose diameter is larger than membrane pore size will be rejected during ultrafiltration process, leaving only water, unsolubilized contaminants and surfactant monomers in permeate stream. The experiments are carried out in a lab-scale plant, where a tubular ceramic ultrafiltration membrane is used with adding a surfactant to concentrate heavy metals in the retentate stream, producing a permeate of purified water that can be reused inside the process, thus minimizing the fresh water consumption.

Treatment of WEEE industrial wastewaters: Removal of yttrium and zinc by means of micellar enhanced ultra filtration

In this paper, the efficiency of micellar enhanced ultrafiltration technique (MEUF) was tested for the removal of yttrium and zinc ions from synthetic industrial liquid wastes. UF membranes (monotubular ceramic membranes of 210 kDa and 1 kDa molecular weight cut-off) were used with adding an anionic surfactant, sodium dodecyl sulfate (SDS). A two - level full factorial design was performed in order to evaluate the effect of molecular weight cut-off, sodium dodecyl sulfate concentration and pressure on the permeate flux and rejection yields. It was found that the single factors presented the largest influence on the permeate flux: the membrane pore size and the pressure had positive effect, instead the SDS had negative effect. Regarding the metal rejection yields the main relevant factors were the membrane pore size with a negative effect, followed by the surfactant concentration with a positive effect. The effect of the pressure seemed to be almost negligible, for zinc removal experiments had a positive effect in the interactions with the surfactant and membrane pore size. The results showed that very good removal percentages up to 99% were achieved for both metals under the following conditions: 1 kDa membrane MWCO, in the presence of the surfactant at a concentration above CMC independently of the investigated pressure.

Integrated process scheme for the combined treatment of liquid wastes and municipal wastewaters: a process analysis

In the following paper, we explored the possibility of integrating the treatment of civil sewage waters with that of liquid wastes, such as landfill leachate, by modifying a typical domestic wastewater process scheme of a real small wastewater treatment plant, located in Southern Italy. In the scheme of the analyzed process, which included the line of treatments for only domestic effluents, a specific line for the treatment of liquid wastes and leachate is added. Liquid wastes are thus pretreated and then simultaneously purified with the municipal wastewaters, in order to fulfill the limits for discharge into superficial water bodies. The process analysis, conducted by performing mass balances on the proposed scheme, has shown that in the case study examined, the treatments carried out (with the removal efficiencies assumed from the literature) are able to produce an effluent, whose concentrations are within the limits of the law dictated by the Italian Legislative Decree n. 152/06 for discharge i...

Thermodynamic features of dioxins' adsorption.

In this paper, the six more poisonous species among all congeners of dioxin group are taken into account, and the P-T diagram for each of them is developed. Starting from the knowledge of vapour tensions and thermodynamic parameters, the theoretical adsorption isotherms are calculated according to the Langmuirs model. In particular, the Langmuir isotherm parameters (K and wmax) have been validated through the estimation of the adsorption heat (ΔHads), which varies in the range 20-24kJ/mol, in agreement with literature values. This result will allow to put the thermodynamical basis for a rational design of different process units devoted to dioxins removal.