Conference Papers

This work is an attempt to describe the advantages, possibilities and INCD – ECOIND results in the utilization of residual organic sludge from animal breeding farms and municipal waste water treatment plants as a potential energy source. INCD – ECOIND (former ICPEAR) started the research in this area in 1980 under the direction of dr.Craiu, manager of our Institute at that time. At the beginning, we elaborated technology design and building of an industrial biogas plant in Timisoara (1983) with a capacity of 250 m3. After that we have developed other large industrial biogas plants with capacities up to 1500 m3, at several industrial breeding farms such as Girov, Veresti, Bacau, Caracal, a.s.o.. After 1989, when the majority of the large industrial animal breeding farms were dismantled, our research was oriented to optimize the anaerobic digestion process of municipal wastewater treatment plants sludge (municipal WWTP’s, Pitesti municipal WWTP) and to characterize the fermented sludge in order to evaluate the possibility to use them as agriculture fertiliser (Constanta and Mangalia WWTP’s fermented sludge). INCD – ECOIND’s conception is that organic residual sludge will be not only a real renewable source of energy in the future but an excellent agriculture fertilizer as well. Our research efforts are now conducted in these directions.

No more cinder was deposited on the dumb starting with 2004. The environmental balance indicates an overflow of heavy metals admitted in soil that shown a major possible pollution. The wastes mining-metallurgical deposits are a continuous pollution source for environment and human habitat. The physical pollution is manifested through the increase of air-floated and sedimentary powders atmosphere content while the chemical pollution is due to the content of the dumper ash in chemical compounds. The surface water, groundwater, soil, vegetation and the leaving area are the pollution receiver. Also, there is the danger of the West and North flank to debris-slide, the last one with the blocking-up of the river bottom.

This paper presents some results of an experimental investigation of the possibility of using an “in-foam UV/air oxidation” process for the degradation of anionic surfactants. In this process, only the foam generated by bubbling air through the surfactant solution is exposed to the UV-C light, followed by recirculation to solution using a positive displacement pump. The developed process, tested for sodium dodecylbenzenesulfonate and sodium dodecylsulfate 0.3-0.5 mM aqueous solutions seems to be promising, even compared with advanced oxidation processes such as UV/H2O2 , depending on photosensitizer dose. Based on the analysis presented in this article the “in-foam UV/air oxidation” process has surprisingly good performances related to both surfactant concentration (primary degradation) and chemical demand (mineralization), but is limited by the lowest useful foaming concentration. The foam acts as a support for photochemical reactions, as it concentrates the surfactant to a high area interface, where it is exposed to the UV light and oxygen. By contrast, when only the solution is exposed to UV light, the “in-solution UV/air oxidation” process, the efficiency is low and, as expected, higher for the UV-absorbing aromatic compound sodium dodecylbenzenesulfonate. The “in-foam UV/air oxidation” process can be used as a pretreatment before biological aerobic treatment of clear waste water containing surfactants and is also an interesting research alternative for the oxidation of other organic compounds. This process can be refined by adding phosensitizers.

Electroseparation of zinc from two soils samples by using of a laboratory installation, in which metal is accumulated in a supported tuff layer, is presented in this paper. Optimum parameters for the treatment of soil-supported tuff systems by electroremediation process were: voltage 25 V, current 48-69.5 mA, pH 2.1-3.8 at anode and 5.5-6.5 at cathode, pH of supported tuff 5.4-6.5, samples humidity 29-31.5%. Efficiencies for zinc retaining in supported volcanic tuff mass from soil sample containing 186 mg/kg d.s., were 65-72.3%, after 72 hours. Analysis of metal concentrations evolution versus time, showed the existence of a homogeneous electromigration process.

In phytoremediation process of soils polluted with heavy metals, the use of amendment with different types of fertilizers and biosolids, will increase process efficiency. Uisng of fertilizers assure nutrients for plants, and increases the acces of metals to their aerial parts, and bioaccumulation above allowable limits. Amendement consisting of native volcanic tuff, with high clinoptilolit content, modified by supporting with Al13 polimers, decreased zinc bioavailability about 1.4 - 2.1 times and that of cadmium 1.4 - 3.8 times, in aerial parts of Vicia sativa plant, in first weeks of vegetation. Uisng of pillared zeolite produced advanced decreasing of cadmium access in Vicia sativa roots, and as a consequence a decreasing in aerial parts of plant during advanced vegetation period.

This paper presents the systematic researches for removal of xenobiotics (trichlorobenzene-TCB, hexachlorobenzene-HCB) from the effluent of classical municipal wastewater treatment plant in order to reuse it for agricultural purposes. Degradation of chlorobenzenes using various photoinduced oxidation processes such as UV/H2O2, UV/O3 and UV/H2O2/O3 was investigated. Comparative analyses of removal efficiencies for TCB and HCB taking into account tested operating parameters were performed. The operating parameters with significant influence upon the removal efficiencies of chlorobenzenes in homogeneous AOPs are as following: micropollutants concentrations, reaction/irradiation time and oxidants doses (H2O2, O3). The selected variant, based on laboratory experiments could be used as tertiary treatment step for the municipal wastewater treatment plant, after verification of microbiological indicators, and the final effluent could be used in agricultural purposes - irrigations.

This study deals with the characterization of electrochemical properties of doped SnO2 anodes by cyclic voltammetry (CV) and their use for Reactive Blue 4 azo dye (RB4) degradation. The experiments were carried out by using Ti/Ru02/SnO2-SbO5-RuO2 anodes (94:3:3 Sn:Sb:Ru molar ratio in precursors solution) prepared by thermal decomposition method. Cyclic voltammograms were recorded at a scan rate of 0.05 V/s and potential range from 0 V to 1.5 V vs. SCE in 0.1 M Na2SO4 and 0.1 g/L RB4. The supporting electrolyte was 0.1 M Na2SO4. Degradation experiments were carried out in solutions of 0.1 g/l DYE IN 0.1 m Na2SO4, applied current densities of 25, 50, 75 and 100 A/m2 at various electrolysis times and pH values: 6.2; 11 and 3. The cyclic voltammograms showed that the oxidation of dye could occur under conditions of simultaneous O2 evolution. The best value for the colour removal efficiency was about 99% for an applied current density of 100 A/m2 and 120 minutes of electrolysis at any pH value.

Degradation of recalcitrant organic compounds such as azo dye is difficult to accomplish because of their complex structure. This paper deals with the electrochemical oxidation of C.I. Reactive Black 5 (RB5) azo dye at dimensionally stable anodes (DSA). The Ti/RuO2/SnO2-SbO5-Bi2O3 electrodes were prepared by thermal decomposition of the appropriate precursors and they were characterized by scanning electron microscopy (SEM) and cyclic voltametry (CV). The SEM image revealed a surface morphology with mud-like cracks and the cyclic voltammograms suggested that the dye oxidation might occur simultaneously with oxygen evolution. The electrochemical oxidation of the dye was carried out in a cell with two anodes of Ti/RuO2/SnO2-Sb2O5-Bi2O3 and three cathodes of stainless steel. The elctrolyte solution consisted of 0.1 g/L dye in 0.1 M Na2SO4 as supporting electrolyte at pH 5.8, 11 and 3. The degradation of the dye was assessed by recording UV-VIS spectra of the electrolysed solutions. Colour removal efficiency higher than 96% was obtained for an apllied current density of 100 A/m2 and electrolysis time of 120 minutes at any value of the pH.

Evacuarile de ape uzate cu continut ridicat in compusi cu azot (amoniu, azotat, azotit) pot fi toxice pentru ecosistemele acvatice conducand la scaderea concentratiei de oxigen si eutrofizarea receptorilor naturali. Cresterea continutului de azot in influentul treptei biologice si restrictiile impuse la evacuare (HG352/2005- NTPA001) conduc la necesitatea optimizarii sau redimensonarii statiilor clasice de epurare. Un aport important de azot este adus in statiile orasenesti de epurare de apele rezultate de la deshidratarea namolului rezidual stabilizat prin digestie anaeroba. Implementarea tratarii locale a apelor de la deshidratarea namolului poate fi o alternativa eficienta economic fata de varianta maririi capacitatii treptei biologice sau de imbunatatire a sistemelor de aerare. Lucrarea prezinta experimentarile de indepartare a ionului amoniu (sute mg NH4+/l) din apele uzate rezultate la deshidratarea namolurilor, intr-o instalatie continua in doua trepte:  bioreactor aerob hibrid (treapta SHARON - TRH = 8 h) la temperatura constanta (35 0C);  bioreactor anaerob cu biomasa in suspensie (ANAMMOX - TRH = 12 h) prevazut cu sistem de agitare mecanica. Datele de caracterizare ale efluentilor dupa adaptarea namolului au evidentiat urmatoarele aspecte:  pentru prima treapta (SHARON) randamentul de transformare a ionilor amoniu in ioni azotit a fost de maxim 99%. Randamentul maxim de indeparte a formelor de azot (azot total) a fost 55%;  pentru treapta a II-a, randamentul de indepartare a formelor de azot a fost de maxim 12% efluentul final incadrandu-se in limita impusa la evacuare (HG352/2005-NTPA002).

This paper presents some results of an experimental investigation of the possibility of using an “in-foam UV/air oxidation” process for the degradation of anionic surfactants. In this process, only the foam generated by bubbling air through the surfactant solution is exposed to the UV-C light, followed by recirculation to solution using a positive displacement pump. The developed process, tested for sodium dodecylbenzenesulfonate and sodium dodecylsulfate 0.3-0.5 mM aqueous solutions seems to be promising, even compared with advanced oxidation processes such as UV/H2O2 , depending on photosensitizer dose. Based on the analysis presented in this article the “in-foam UV/air oxidation” process has surprisingly good performances related to both surfactant concentration (primary degradation) and chemical demand (mineralization), but is limited by the lowest useful foaming concentration. The foam acts as a support for photochemical reactions, as it concentrates the surfactant to a high area interface, where it is exposed to the UV light and oxygen. By contrast, when only the solution is exposed to UV light, the “in-solution UV/air oxidation” process, the efficiency is low and, as expected, higher for the UV-absorbing aromatic compound sodium dodecylbenzenesulfonate. The “in-foam UV/air oxidation” process can be used as a pretreatment before biological aerobic treatment of clear waste water containing surfactants and is also an interesting research alternative for the oxidation of other organic compounds. This process can be refined by adding phosensitizers.

Phenol can be removed from wastewater by biological treatment, which is generally preferred to physical or chemical treatment methods, because of lower costs and the possibility of complete mineralization. Many bacteria are capable of using aromatic compounds such as phenol as the sole source of both carbon and energy. While phenol, wastewater are usually treated in continuous activated sludge processes, these systems are known to be sensitive to high phenol loading rates and to fluctuations in phenol loading. Formation of microbial granules from activated sludge flocs, under aerobic conditions is currently an active area of investigation for developing new generation wastewater treatment plants for high strength organic wastewater, bioremediation of toxic aromatic pollutants including phenol, toluene, pyridine and textile dyes, removal of nitrogen, phosphate and adsorption of heavy metals. Aerobic granules have been successfully cultivated, previously, in SBR systems from flocculated activated sludge fed with acetate as the sole carbon source. The main objective of this study was to investigate how phenol loading affected the structure and activity of aerobic granules. The results indicated that phenol loading exerted a profound influence on the structure and activity of the aerobic granules. Compact granules with good settling ability were maintained at loading up to 3.0 kg phenol m-3 day-1, and structurally weakened granules were observed at the highest loading of 3.7 kg phenol m-3 day-1. Phenol-degrading aerobic granules possess high activity, compact structure and good settleability, and have the potential to treat wastewater with high phenol loading in sequential system at relatively low hydraulic retention times.

Dissolved organic matter, DOC [mg C/L], is a representative parameter for the content of organic matter in natural waters. Along the A254 absorbance as a measure or organic compounds determined at λ = 254 nm UV [cm-1], DOC underlies the calculation of SUVA (Specific Ultraviolet Absorbance) = A254/DOC x 100 [L m-1 mg-1]. SUVA can be used to describe the composition of the water in terms of hydrophobic/hydrophilic character. The study results are presented in the coagulation process with pre-hydrolyzed aluminum salt, as a polyaluminum chloride (PACl), a simple salt of Al, as an Al sulfate (Alum), applied to surface water intended for drinking water. From SUVA values DOC removal efficiency in the coagulation process is estimated. SUVA= 2-4 estimated efficiency of 25-50% removal in DOC. When using PACl, DOC removal efficiency is within the range of 27-53%, and slightly lower when using Alum. SUVA values < 2 indicate DOC removal efficiencies < 25%. DOC removal efficiencies obtained from the use of Alum are within the range 5.6- 8.4% and those obtained used as ciagulation agent PACl are in the range 20.8-23.8%.

The photocatalytic degradation of pollutants using Ti02 nanopowders Or TiO thin films is very attractive for applications to environmental protection, as a possible solution for water depollution. The impurity doping represents one of the typical approaches in orde to extend the spectral response of a wide band gap semiconductor to visible light. The aim of the present work was to establish the influence of the S-dopant on the photocatalytic properties of the TiO2 nanopowders. The relationship between the synthesis conditions and the properties of the un-doped and S-doped Ti02 materials, such as thermal stability, phase composition, crystallinity, morphology, and size of particles, and the influence of the dopant were investigated. The influence of S on TiOz2 crystallization was also studied (lattice parameters, crystallite sizes, internal strains). The photocatalytic activities of the prepared TiO2 based nanopowders were determined by testing them in the degradation of different chloride organic compounds from aqueous solutions. It was established that the presence of S dopant in the TiO2 powders has improved their photocatalytic activities.

Aerobic granular sludge has several advantages over conventional activated sludge flocs such as fast settling ability, high biomass retention and ability to withstand high organic loading including potential toxic substrates, leading towards a compact reactor system – aerobic granular sludge sequential batch reactor (AGSBR). Aerobic granules have been successfully cultivated, previously, in SBR systems from flocculated activated sludge fed with synthetic medium with acetate as the sole carbon source or with real municipal wastewater. The main objective of this study was to investigate the possibility of an aerobic granular system to simultaneously remove the organic loading, nitrogen and phosphorus content. The experiments were performed in a SBR reactor with a hydraulic reaction time of 12 hours at loading rates of up to 3.0 kg m-3 day-1 COD and 0,2 kg m-3day-1 of N-NH4+. Compact granules with good settling ability were maintained during the experimental period and high COD removal but ordinary global nitrogen and phosphorus removal efficiency were registered. Aerobic granules possess high activity, compact structure and good settling ability, and have the potential to simultaneously treat wastewater with high organic and ammonium loading in sequential system at relatively low hydraulic retention times.

The removal of the non-steroidal anti-inflammatory drug diclofenac (DCF) was carried out by electrooxidation on Dimensionally Stable Anodes (DSA) with the composition Ti/RuO2-TiO2. The DSA electrodes were obtained by thermal decomposition of the appropriate precursors. The electrolyses were carried by using solutions of 100 mg/L DCF in 0.1 M Na2SO4 supporting electrolyte in acidic medium at various current densities and electrolysis times. The removal of DCF was assessed by recording UV-VIS spectra and chemical oxygen demand (COD) determination of the electrolysed solutions. The results showed the mineralization of the DCF during the electrooxidation on Ti/Ru0.3Ti0.7O2 electrodes.

The electrooxidation of anti-inflammatory drug diclofenac (DCF) on Dimensionally Stable Anodes (DSA) and Boron Doped Diamond (BDD) electrode was investigated by cyclic voltammetry. The experiments were carried out in aqueous solutions by using 0.1 M NaSO4 supporting electrolyte. The DSA electrodes were prepared by thermal decomposition of appropriate precursors, while the BDD electrode was commercially produced. The DSA electrodic compositions were Ti/RuO2-TiO2 and Ti/RuO2/SnO2-Sb2O5. The recorded voltammograms showed that DCF direct oxidation did not occur on DSA and the oxidation could occur in the potential range of oxygen evolution. The electrooxidation of DCF on BDD electrode was possible by direct oxidation.

Sulphate is the most common anion in mine waters due to the oxidation of sulphide minerals. Even though sulphate is not a toxic substance it can attack concrete structures, and it can affect water usage downstream of mining areas. Despite the European Water Framework Directive, EU Member States have very different approaches to dealing with sulphate containing mine waters. For example, in Germany the site-specific sulphate pollution situation and ecological parameters of surface waters, based on an environmnetal impact analysis, are used to determine the sulphate effluent limits. In Romania and some other countries, a relatively low fixed legal limit (600 mg/L) has to be complied with. In this context the consulting firms WISUTEC GmbH, EcoInd Bucharest and UIT Unwelt-und Ingenieurtechnik GmbH have developed two effective technologies to treat highly polluted mine water including sulphate removal. The first technology utilises heavy metal precipitation followed by the precipitation of ettringite for sulphate removal; whilst teh second utilises nano-filtration (NF), after a chemical "pre-treatment" stage, to produce a high quality permeate. Reagents tested for NF pre-treatment included hydrated lime, sodium hydroxide and magnesium oxide. Similarly, a range of reactive aluminium sources (calcium aluminate, aluminium rich cements, aluminium hydroxide and others) were tested to optimise the precipitation of ettringite. Both flow shhets developed by laboratory test work are well-suited to treat acid rock drainage (ARD) at the Rosia Montana mine site in Romania.

Ibuprofen (IBP) was chosen as a model for non-steroidal anti-inflammatory drugs and its degradation in aqueous solution was carried out by electrochemical oxidation on Dimensionally Stable Anodes (DSA). The DSA had the compositions: Ti/Ru02/SnO2-SbO5-RuO2. The electrolysis were carried in basic medium by using solutions of IBP or IBP and sodium carboxymethyl cellulose (CMC) in 0.1 M Na2SO4 supporting electrolyte. The removal of IBP was assessed by recording UV spectra and total organic carbon (TOC) or chemical oxygen demand (COD) of the electrolysed solutions. The results showed the effectiveness of DSA in IBP degradation in aqueous solutions both in the matrix that contains only IBP and those containing also CMC.

Applying the complex treatment of sewage sludge fertilization and amendment of indigenous volcanic tuff of Marsid, caused a grass coverage degree of 85%. Plants grow similarly to those on normal agricultural soil. The reduction efficiency of Total Petroleum Hydrocarbons (TPH), from the soil fertilized with anaerobically stabilized sewage sludge of 25 t/ha d.m. and amended with indigenous volcanic tuff 2.5 t/ha is of 33.7%, during a four month period, with over 10% more than the efficiency of reduction of the Total Petroleum Hydrocarbons content from the soil of the experimental variant fertilized with sewage sludge in the absence of amendments.

Urban development produces wastewaters with flow and/or concentration peaks which prejudice the well functioning of a wastewater plant designed for influent categories characterized by certain domains of composition and concentration. This study aimed to investigate the conventional physico-chemical and biological treatability parameters of the influent and the removal efficiency of the treatment plants: high carbonic loading, chemical oxygen demand (COD), and low biodegradability as BOD5/COD (biochemical oxygen demand/chemical oxygen demand) ratio. The improvement of the biological biodegradability parameters in order to obtain a proper activated sludge was achieved by optimal oxygen and nutrients addition. Molasses addition to correct the BOD5/COD ratio to values ≥ 0.4, determines the increase up to 60-80% of biodegradable organic matter mineralization. COD efficiency removal increases by 1-20% vs. the results obtained for oxygen deficit and/or low biological treatability.