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Laboratory scale investigation has been carried out for the optimization of a new process for separation and recovery of Pb/Fe species from automobile battery manufacturing wastewaters. The innovation, based on ion exchange, allows for separation and recovery of the mentioned species by the use of a commercial weak anion resin (Duolite A7 from Rohm&Haas Co, USA), as selective sorbent for the ferric species, and a weak cation resin with carboxylate functionality (Purolite C106 from Purolite Co.,UK) for removal and recovery of lead species. Cl-form anion resin was eluted with real automobile battery wastewaters (pH 3; F-es= 4BV/h; influent Fe concentration: 2 mg/L) for a column throughput exceeding 200 BV (Bed Volumes) with Fe leakage steadily below 0.2 mg/L, (ten times lower the maximum allowable concentration, MAC, for discharge in closed water bodies, enforced by EU legislation). Lead species were removed and recovered on Na/H-form cation resin (pH 6; F-exh=20 BV/h; influent Pb concentration: 4 mg/L) for a column throughput exceeding 15,000 BV at average Pb leakage below 0.03 mg/L (MAC=0.2 mgPb/L). Both sorbents were regenerated by limited amounts of 1M HCl. Specifically, resin Duolite A7 was eluted with 5 BV (F-reg=2BV/h), and carboxylate resin was eluted with 30BV (F-reg=10BV/h). Recovery of metal species from resin spent regeneration eluates may be obtained by neutralization and quantitative precipitation of hydroxycerussite [basic lead carbonate, (Pb-3(OH)(2)(CO3)(2)], ready for reuse in the same battery industry and/or other productive activities. Ferric chloride in the resin spent regeneration eluate was directly recycled as coagulant to the wastewater treatment operations.

The paper reports the results of a laboratory investigation aimed at evaluating the effectiveness of an innovative technology, SBBGR (sequencing batch biofilter granular reactor), based on aerobic granular biomass, for treating diluted (i.e., municipal wastewater) or concentrated (i.e., municipal landfill leachates) wastewater. When this technology was applied to the treatment of municipal wastewater, the results showed that, even at maximum organic load (i.e., 7 (kg of COD)/m(3).d), the chemical oxygen demand (COD) in the treated effluent was lower than 50 mg/L. In addition, total Kjeldahl nitrogen (TKN) removal efficiency was higher than 87% up to an organic load of 5.7 (kg of COD)/m(3).d, corresponding to a nitrogen load of 0.8 (kg of TKN)/m(3).d. During the treatment of a mature municipal landfill leachate, the SBBGR proved suitable for removing the entire biodegradable compound content (i.e., about 80% of the COD content of the leachate) up to an applied organic loading value of 1.1 (kg of COD)/m(3).d. During the whole investigation, the process was characterized by a low sludge production, about I order of magnitude lower than that of conventional systems.

Within a strategic R&D project, since April 2002, membrane filtration, simplified treatments, storage reservoirs and constructed wetlands technologies are under investigation, at field scale, to evaluate their effectiveness for treating municipal effluents to be reused in agriculture. So far, the main results recorded have been the following: membrane filtration — the microbial quality of treated effluents was higher than that of local well-water used for irrigation; simplified treatment — in order to save the agronomic potential of organic matter and nutrients present in urban wastewater, olive trees were irrigated with effluents produced by skipping biological processes and this resulted in a yield increase of 50%; storage reservoirs — TSS, BOD5, COD and nutrients concentrations achieved the in force Italian limits for WW agricultural reuse; constructed wetlands — recorded average efficiencies for TSS, BOD5, COD, TN and TP removals were 85%, 65%, 75%, 42% and 32% respectively.

The paper reports the results of an investigation carried out at lab scale to assess the effectiveness of an innovative technology (SUPERBIO) for treating municipal and/or industrial wastewater. When this technology was applied for treating municipal wastewater, the results showed that even at maximum organic load (i.e. 7 kg COD m(-3) d(-1)), the COD in the treated effluent was lower than 50 mg L(-1). In addition, both ammonia and TKN removal efficiencies resulted in higher than 87% up to an organic load of 5.7 kg COD m(-3) d(-1) corresponding to a nitrogen load of 0.8 kg TKN m(-3) d(-1). Very satisfactory process performances also resulted during tannery wastewater treatment, when a chemical oxidation step (i.e. ozonation) was inserted in the treatment cycle of SUPERBIO. In such an instance, at organic and nitrogen loadings of 3 kgCOD m(-3) d(-1) and 0.20 kg N m(-3) d(-1), COD, NH4+ -N and TSS average removals were 96, 99 and 98%, respectively. Finally, during the whole experimentation, SUPERBIO was always characterised by a very low sludge production. Such a result was ascribed mainly to the characteristics of biomass that grew in the form of very dense granules (i.e. 130 gVSS L(Biomass)(-1) allowing a biomass concentration as high as 50-60 gTSS l(bed)(-1) to be achieved.

This work presents a thorough fractionation of COD in raw sewage, followed by pilot plant coagulation tests with low-dosage lime (pH 9). Through a physical separation (sieving and crossflow filtration) total COD in the raw sewage was partitioned among eight size fractions in the range of 150-0.02 microm. In addition, respirometric tests were performed to measure the biodegradability of the different size fractions. More than 60% of COD was associated with settleable and supracolloidal particles (size > 1 microm), which are characterised by slow biodegradability. Coagulation with lime increased COD removal efficiencies in the primary treatment from typical 30-35%, up to 65-70%, suggesting that lime may induce the almost complete removal of the slowly settling, slowly biodegradable supracolloidal particles in the primary treatment. On the basis of these results a non-conventional sewage treatment scheme is proposed, considering that there is plenty of space for improving primary treatment efficiency through sewage coagulation. Higher primary treatment efficiency may present several advantages, including lower aeration energy in the subsequent biological unit and higher energy recovery from sludge digestion.

The UV-induced photocatalytic degradation of two azo dyes, Methyl Red and Methyl Orange, has been carried out in aqueous media in the presence of oleic acid (OLEA)- and tri-n-octylphosphine oxide (TOPO)-capped anatase TiO2 nanocrystal powders (mean particle size: 6nm) deposited onto a quartz substrate. The progress of photodegradation was followed by combining UV–vis absorption measurements with HPLC–MS analysis. The abatement efficiency for the two organic compounds was compared with that obtained with commercial TiO2 P25 Degussa by evaluating a few significant variables, such as the dye chemical structure, pH of the solution, and catalyst surface status. Identification of several by-products by HPLC–MS analysis has allowed to propose a reasonable degradation pathway for both target molecules. Significantly, although all titania catalysts were effective in removing both parent dyes and their related derivatives, the degradation rate by the OLEA-capped TiO2 nanocrystals was double as that obtained with both its TOPO-capped analogous and TiO2 P25 Degussa. It is suggested that efficient catalysis strictly depends on microscopic mechanisms that occur at the catalyst surface, basically involving specific dye adsorption and local density of terminal OH moieties.

The paper reports the results of an investigation aimed at evaluating the performances of a periodic biofilter (SBBR) for treating municipal wastewater. The investigation was carried out at laboratory scale on real primary effluent coming from a municipal wastewater treatment plant located in Southern Italy. The SBBR was designed for carbon and nitrogen removal through one single stage. The results have shown that even at maximum organic load (i.e., 7 kg COD/m3.d), the COD in the effluent was lower than 60 mg/L. TKN removal efficiencies resulted high (i.e. 90-95%) up to an organic load of 5.7 kg COD/m3.d corresponding to a nitrogen load of 0.8 kg TKN/m3.d. NO3-N concentration in the treated effluent was lesser than 6 mg/L although in the SBBR treatment cycle no anoxic phase was scheduled. This indicated that denitrification extensively took place in the biofilter. The process was characterized by high suspended solids removal (about 90%) and by a negligible sludge production (lower than 0.01 kgVSS/kgCODremoved). In the SBBR, biomass grew as granules and was characterised by different measurements (biomass concentration, cellular protein and biomass density). Biomass density resulted very high, i.e. 200 gTSS/Lbiomass, and this permitted to achieve a biomass concentration such high as 40 gTSS/Lbed. Such biomass concentration did not cause any decrease of biomass metabolic activity as proved by its total protein content (29% of organic matter) and maximum oxygen uptake rate value (i.e. 50 mgO2/gVSS h).

This paper reports the results of an experimental study specifically aimed at developing a simple methodology for calculating hydrodynamic shear forces in a sequencing batch biofilm reactor (SBBR) system with granular biomass. Using such a methodology, the hydrodynamic shear forces are simply calculated by measuring bed porosity and pressure losses. In addition, by applying this methodology an explanation for the biomass evolution from biofilm to granules under aerobic conditions has been provided and the following mechanism has been proposed: (i) formation of a thin biofilm that fully covers the carrier; (ii) increase of biofilm thickness; (iii) break-up of the attached biofilm with release of biofilm particles; (iv) rearrangement of biofilm particles in smooth granules. The hydrodynamic shear forces trend during the start-up period provides an explanatory key for the generation process of granular biomass. In fact, during the first two steps, the SBBR is characterized by rather weak shear forces values (lower than 1 dyn/cm2). Under these weak shear forces, the biofilm grows by increasing its thickness through a porous structure and weak adhesion strengths. Such a continuous increase of biofilm thickness produces an increase of the shear forces with negative effect on biomass stability, causing the detachment of biofilm particles. In turn, such detachment causes a further sharp increase of shear forces (more than 10 times) that promotes the rearrangement of the detached biofilm particles in smooth granules. A correlation between biomass density and hydrodynamic shear forces was observed. In particular, the biomass density linearly increases with the increase of shear stress.

The paper reports the results of an investigation aimed to evaluate the influence of hydrodynamic conditions on physical and biochemical characteristics of granular sludge obtained in a SBBR system. Biomass density resulted very high, i.e. 70-125 gTSS/L(biomass), and this permitted to achieve a biomass concentration such high as 17-45 gTSS/L(bed). An appropriate equation proved that the pressure loss, an easily measurable parameter, can be used for biomass porosity measurement and indirect assessment of biomass concentration in the biofilter. As for biomass biochemical characterisation, the EPS (Extracellular Polymeric Substances) content was rather low (5-7% of the total organic matter) and mostly made up of proteins whereas the cellular protein content, a parameter frequently used as an indicator of microorganisms activity, was high (30-60% of total organic matter).

The paper reports the results of an investigation aimed to evaluate the performances of an innovative process for treating tannery wastewater. In such a process biological degradation, carried out in a sequencing batch biofilm reactor (SBBR), is combined with chemical oxidation by ozone. The treatment was carried out at laboratory scale on a real primary effluent coming from a centralized plant treating the wastewater of a large tannery district in Northern Italy. SBBR performances without and with ozonation were compared with very satisfactory results particularly in the latter instance when the recorded COD, TKN, and TSS average removals, (96%), (92%), and (98%), respectively, permitted to achieve the fixed limits enforced by Italian regulation without needing any additional polishing step. With or without ozonation, the process that resulted was characterized by a specific sludge production (0.1 kgVSS/kg CODremoved) significantly lower than the values featuring conventional biological systems (i.e., 0.3-0.5 VSS/kg CODremoved). Moreover, as in the reactor the biomass density results were very high, i.e., 98 gVSS/Lsludge, it was possible to achieve and maintain biomass concentration as high as 20 gVSS/L.

Pollutants in municipal sewage include a complex mixture of soluble and insoluble constituents ranging in size from less than 0.001 μm up to over 100 μm [1]. Several studies have been addressed to the classification of contaminants in wastewater in terms of particle size. Balmat [2], Heukelekian and Balmat [3] and Rickert and Hunter [4], using a sequence of sedimentation, centrifugation and filtration, separated the contaminants into four size fractions: settleable (> 100 μm), supracolloidal (1–100 μm), colloidal (0.08–1 μm), and soluble (< 0.08 μm). On the basis of a sequential filtration of the wastewater, Munck et al. [5] used a slightly different definition of the four size ranges: settleable (> 106 μm), supracolloidal (3-106 μm), colloidal (0.025–3 μm), and soluble (< 0.025 μm). Notwithstanding the differences in the operating definition of the size ranges, these studies do agree that only a quarter or less of the COD of the raw sewage may be considered truly soluble [6]. The majority of the pollutant load is actually in suspended form, and is not easily biodegradable. In addition, other contaminants, such as heavy metals, bacteria and viruses, and organic micro pollutants (PCB, PAH) are strongly associated with the suspended phase.

Treatment, removal and recovery of lead (3 mg/L) from battery industry wastewaters have been investigated utilising a chemical precipitation process with soluble starch xanthate (SX) at pH 5-6. A reactant ratio, i.e., SX/Pb(II) = 6 mol/mol, a reaction time of 15 min., the addition of 15 mg/L of a cationic polyelectrolyte and a final filtration gave residual lead concentrations in the liquid phase less than 0.2 mg/L, well below the maximum limit established by the EU Directive. Lead was extracted from the obtained sludge by oxidation with sodium hypochlorite or hydrogen peroxide solutions. The amounts of oxidant needed were quantified as 13.5 mol NaClO/mol Pb and one order of magnitude larger, for H2O2, the latter due to the competitive disproportion reaction of the oxidant. The metal extraction was quantitative using sodium hypochlorite; when hydrogen peroxide was used, the formation of insoluble PbSO4 (Anglesite) gave a 80% metal extraction. In both cases molar ratios between sulphate and lead ions in the extracted solutions were in the range 2.1-2.2, in agreement with the stoichiometries of the reactions. Lead can be quantitatively recovered from the extracted (NaClO) solutions, for reuse, after a chemical precipitation process with 1M NaOH at pH 9-9.5, in the form of hydrocerussite [Pb3(CO3)2(OH)2].

The paper reports on the results of an investigation aimed to evaluate the performances of an innovative tannery wastewater process based on the combining biological degradation, carried out in a sequencing batch biofilm reactor, with chemical oxidation, performed by ozone. The combined treatment was carried out at the laboratory scale on real primary effluent coming from a centralised plant treating the wastewater from a large tanning district in Northern Italy. SBBR performances with and without ozonation were compared resulting to be very satisfactory only in the latter instance where recorded COD, NH4-N and TSS average removals were 97%, 98% and 99.9%, respectively. Such efficiencies correspond to specific concentrations in treated effluent well below the limit values fixed by the in-force Italian regulations. Furthermore, it was proved that the combined process is characterised by a very low sludge production. In fact, the measured specific sludge production (0.03 kg TSS/kg COD(removed)) resulted unexpectedly much more lower than the value reported for conventional biological systems (i.e., 0.3-0.5 kg TSS/kg COD(removed)).

ABSTRACT Laboratory scale investigation has been carried out for the optimization of a new process for separation and recovery of Pb/Fe species from automobile battery manufacturing wastewaters. The innovation, based on ion exchange, allows for separation and recovery of the mentioned species by the use of a commercial weak anion resin (Duolite A7 from Rohm&Haas Co, USA), as selective sorbent for the ferric species, and a weak cation resin with carboxylate functionality (Purolite C106 from Purolite Co.,UK) for removal and recovery of lead species. Cl-form anion resin was eluted with real automobile battery wastewaters (pH 3; Fes= 4BV/h; influent Fe concentration: 2 mg/L) for a column throughput exceeding 200 BV (Bed Volumes) with Fe leakage steadily below 0.2 mg/L, (ten times lower the maximum allowable concentration, MAC, for discharge in closed water bodies, enforced by EU legislation). Lead species were removed and recovered on Na/H-form cation resin (pH 6; Fexh=20 BV/h; influent Pb concentration: 4 mg/L) for a column throughput exceeding 15,000 BV at average Pb leakage below 0.03 mg/L (MAC=0.2 mgPb/L). Both sorbents were regenerated by limited amounts of 1M HC1. Specifically, resin Duolite A7 was eluted with 5 BV (Freg =2BV/h), and carboxylate resin was eluted with 30BV

Biodegradation of organic pollutants is based on 'destructive' technologies leading to the formation of low-molecular-weight compounds and carbon dioxide or methane depending on the process red-ox conditions. This is not possible for persistent pollutants (e.g., heavy metals, biorefractory organics, complex organometals) independent of the origin and structure of the chemical substrate. Reference compounds can only be recovered and eventually recycled to the production lines of origin and/or to related industrial activities. However, the quality of the recovered products must justify the recycling operation. Sorption techniques lion exchange, carbon adsorption) and membrane technology as typical 'conservative' unit operations allow for removal of pollutants to the strictest limits imposed by enforced legislation and simultaneous recovery and recycling. We discuss two examples of conservative environmental technologies, based on ion exchange and the use of reactive polymers. The first relates to metal-laden effluents from the tannery industry, and the second to the management of residues (clarifier sludge) from the drinking water industry. Both processes are aimed at the minimization of environmental impact resulting from the production lines (Cr(III)- and Al(III)-containing wastes, respectively) and the recovery of valuable by-products with the related economic revenues associated with their commercial value. (C) 2000 Elsevier Science B.V. All rights reserved.

Several million tons per year of water clarifier sludge are produced in Europe, with forecasts of the figure doubling by the next decade. End disposal of reference sludge is mainly based on controlled landfilling, after conditioning to minimise the volume of solids. The conditioning operation is carried-out in acidic or alkaline media, thus also allowing for coagulants recovery (AI, Fe species). The quality of the chemicals recovered may not be sufficient to justify their reuse, e.g., to water clarification operations.With the aim of improving the purity of coagulants recovered, a new ion exchange process for selective removal, separation and recovery of Al(III) and Fe(III) species from the clarifier sludge is presented. The IERAL (Ion Exchange Recovery of Aluminium) process is based on the use of a commercial weak electrolyte carboxylate resin (Purolite C106, from Purolite Co., UK), allowing for the removal of metals from the clarifier sludge acidic leachate (pH 3.5), followed by selective separation and recovery of the aluminium and ferric species during the resin regeneration step.Together with the performance of a fully automated 50 L/d pilot plant, this paper reports the basic principles of the process. (C) 2000 Elsevier Science Ltd. All rights reserved.

Technical feasibility of an ion exchange process for removal and recovery of lead present in battery manufacturing wastewaters is demonstrated. In absence of aluminium and ferric species, lead is quantitatively removed and recovered (approximate to 90%) from the neutralised wastewaters after elution on the natural zeolite clinoptilolite. Control of pH to 5.5-6 is necessary to minimise degradation of the exchanger material. Throughput volumes exceeding 2,700 bed volumes (BV) (flowrate: F-exh= 10 BV/h) is obtained, when the initial Pb concentration is 4 mg/L, with the metal leakage steadily below the maximum allowable concentration (MAC<0.2 mgPb/L) set by the EU for discharge in rivers, lakes, coastal seawater. Regeneration of the zeolite is carried out by controlled elution of limited amounts of 1M NaCl, pH 4.5 (40BV, F-reg=5 BV/h) to minimize in situ precipitation of metals and preserve the zeolite from degradation. From spent regeneration eluate lead is recovered to the battery manufacturing operations. This latter operation is carried-out by precipitation in the form of hydroxycerussite (basic lead carbonate) or electrolysis as pure metal. In this way it is minimized the environmental impact after waste disposal (no hazardous waste formation) and, at the same time, it is recovered raw materials to the productive lines of origin (environmental protection and resource conservation). The exhausted mother liquors from lead precipitation operation is recycled to the subsequent zeolite regeneration step, after back-up of the initial regenerant concentration and solution pH.

A new technology for removal and recovery of coagulants from water clarifier sludge has been optimized at laboratory scale pilot plant level. The process is based on the use fibrous exchangers showing good kinetic and thermodynamic performance toward coagulant species (Al, Fe) present in the acidic leachate (pH 3.5) from water clarifier sludge. The innovation allows for the solution of the environmental problem related to clarifier sludge disposal (residual solids after metals leaching are safely applied to land), and quantitative recovery of coagulants to the water potabilisation operations.Process optimisation, by using real clarifier sludge from the Sinni River Water Works (Apulian Water Authority, S.E. Italy), was carried-out and results are illustrated in the paper. A commercial weak cation fibrous exchanger (Fiban K4) with carboxylate functionality, selectively removed aluminium and ferric species in "moving bed" unit operations with the resin re-circulating through the stationary exhaustion and regeneration baths. Resin regeneration was efficiently carried-out by the use of 0.4M NaOH solution for quantitative recovery of almost pure coagulants, ready for reuse. Together with process optimisation, the paper also reports some mechanistic indications on the fibrous resin performance toward polyvalent metal species retention at the resin functional groups.