István Licskó

Budapest University of Technology and Economics · Department of Sanitary and Environmental Engineering

A hazai vízkivétel jelentős része felszín alatti vízbázisokból történik; a felszíni vízből származó ivóvíz aránya Magyarországon csupán néhány százalék. Jelen tanulmány áttekinti, hogy a felszíni vizekben jellemzően milyen szennyezőanyagok fordulnak elő, majd bemutatja azok eltávolítására szolgáló technológiákat. A felszíni vizekben található szilá...

In this study, the factors that leading to loss of chlorine residual in water distribution systems were investigated. A series of experiments performed on real water samples collected from effluent of water treatment plant before chlorination. The results showed that bulk chlorine decay rate varied significantly with the initial chlorine concentrat...

Jar tests with synthetic water were carried out in order to investigate the effect of phosphate, bicarbonate and silicate on arsenic removal efficiency by in-situ formed ferric hydroxide. Above 12 mg C/L inorganic carbon concentration, the adverse effect of bicarbonate was definite, and resulted in higher remaining arsenic concentration. At all pH...

Batch and continuous experiments using model and real wastewaters were conducted to investigate the effect of metal salt (ferric and alum) addition in wastewater treatment and the corresponding phosphate removal from a design and operational perspective. Key factors expected to influence the phosphorus removal efficiency, such as pH, alkalinity, me...

The EU Water Framework Directives (WFD) prescribes to achieve a good status of surface waters by 2015. To keep this deadline of a new three level (surveillance, operational and investigative) monitoring system is required, including hydro-morphological, biological and chemical elements. The status of a water body should be related to the reference...

Achieving phosphate removal to very low levels recently refocused the attention of the wastewater engineering profession on the design principles and various mechanisms that can produce effluent phosphate concentrations below 10 μgP/L (with TP being usually less than 100 μgP/L or 0.10 mgP/L). Current equilibrium models used for design (WEF, 1998) a...

Laboratory and full-scale experiments were performed in order to investigate the effect of mixing, as represented by the mean velocity gradient, G-value (Grady et al, 1999), and time dynamics in chemical phosphorus removal. The results prove that the chemical reactions occurring during phosphorus removal upon addition of trivalent metal salts (Fe,...

During the implementation of Water Framework Directive (WFD) of the European Union an important and urgent task is to develop a three-level monitoring system (surveillance, investigative and operational). The monitoring system should meet at least two conditions: determination of the characteristic status of the water body and statistical evaluatio...

Hydrolysis of trivalent metal coagulants (aluminium and ferric salts) was studied and evaluated. It was demonstrated that hydrolysis and the transformation of water soluble aluminium- and ferric-hydroxide polymers (complexes) into weakly water soluble sols are very quick processes. The sol particles have positive electric charge, and they are able...

The South-Budapest Wastewater Treatment Plant (SBWWTP) had been operated as a high-load activated sludge (AS) plant since the middle of the 60s. According to the requirements proposed by the water authorities the treatment process had to be upgraded into nutrient (phosphorus and nitrogen) removal. The upgrade of the plant comprised implementation o...

Possible coagulation mechanisms were studied in relatively high alkalinity model systems and surface waters. On the basis of available information, original laboratory experiments and simple calculation were performed in order to show that the adsorption of Al3+ and Fe3+ ions is not the dominant process in decreasing the stability of suspended part...

One of the most valuable uses of data from the ICP Waters program is evaluation of long-term trends. Trend analyses have been conducted previously on ICP Waters data and have provided important indications of the geographic extent of acidification and recovery of lakes and streams (Lükewille et al. 1997, Newell and Skjelkvåle 1997, Skjelkvåle et al...

Different pollutant (organic matters and phosphorus) removal efficiencies of chemical pretreatment were investigated in lab-scale experiments. The results demonstrated that 55-80% of organic content and 85-95% of phosphorus removal have been reached, while the residual organic matter concentration did not exceed 200 mgl-’ as COD&, and 120 mgl-’ as...

Presently the objective of urban water management is to deal jointly with water and material budgets, preferably in such a way as to establish closed cycles. The strategic analysis was made for two time horizons: For the period until Hungary joins the EU and for a longer period after that. This study analyses the strategic questions of drinking wat...

The poorly recultivated tailings at the R. Ore Mines Co. site also contain large amounts of pyrite. Owing to oxidation and acidification processes triggered by oxygen-saturated acid rain, heavy metals are transported by the leachate via the groundwater to surface streams of high buffering capacity where the metals are precipitated within a brief pe...

After 80 years of operation health authorities have closed down a plant processing non-ferrous scrap metals. The ruling had both beneficial and adverse environmental impacts. The benefits include elimination of direct air pollution by metal compound emissions, but the metal-bearing dust deposited over 80 years and stirred up by winds is still a sou...

After 80 years of operation health authorities have closed down a plant processing non-ferrous scrap metals. The ruling had both beneficial and adverse environmental impacts. The benefits include elimination of direct air pollution by metal compound emissions, but the metal-bearing dust deposited over 80 years and stirred up by winds is still a sou...

The poorly recultivated tailings at the R. Ore Mines Co. site also contain large amounts of pyrite. Owing to oxidation and acidification processes triggered by oxygen-saturated acid rain, heavy metals are transported by the leachate via the groundwater to surface streams of high buffering capacity where the metals are precipitated within a brief pe...

The processes leading from coagulant feed to the development of flocs suited to solid-liquid phase separation are examined and analyzed in the light of available information and experimental data. It is concluded that at the relatively high buffering capacity (HCO3- concentration above 1.8 megAL) and close to neutral pH values (7.0<pH<8.4) typicall...

The processes leading from coagulant feed to the development of flocs suited to solid-liquid phase separation are examined and analyzed in the light of available information and experimental data. It is concluded that at the relatively high buffering capacity (HCO3− concentration above 1.8 meg/L) and close to neutral pH values (7.0<pH<8.4) typicall...

Water-supply reservoirs in the Czech Republic, Slovakia and Hungary differ in several ways. While reservoirs are used frequently as water sources in the Czech Republic, they are used less often in Slovakia and Hungary because of the availability of groundwater. The volume of man-made Hungarian reservoirs is usually one order of magnitude smaller th...

To improve the organics removal efficiency of surface water treatment technologies, powdered activated carbon (PAC) has often been added. Some of the PAC particles with the dissolved organics already adsorbed are present in the form of a colloidal quasi-colloidal dispersion and can be removed most efficiently by coagulating and flocculating them to...

During the coagulation-flocculation processes involved in the treatment of surface waters, dissolved organics are also incorporated into the aluminium and iron (III) hydroxide flocs. A part of the dissolved organics can thus be removed by simple solid-liquid phase separation techniques, like sedimentation, flotation, sand filtration. According to l...

A method has been developed for removing the dissolved chromium(VI) and nickel compounds from groundwaters polluted as a consequence of uncontrolled solid wastes disposal. The chromium(VI) compounds (4-25 mg/L)were reduced in both neutral and alkaline media (10.0-11.0 pH range) with the help of FeSO4.7H2O. The partly colloidal, poorly water-soluble...

The changes in the concentration of seven heavy metals (Hg, Cd, Pb, Cr, Ni, Cu, Zn) in the water, sediment and aquatic organisms were studied in the River Zala, the largest tributary to Lake Balaton, and in the retention pond (Balaton Minor) created on the tributary. The samples have been collected at four stations, in ice-free periods, at monthly...

The physico-chemical, chemical and biological processes involved in water and sewage treatment take place most efficiently in neutral media, i.e. in the pH range around 7.0. In some instances, however, for attaining the desired degree of pollutant removal (e.g. removal of heavy metals, ammonia stripping, lime-soda water softening) it is necessary t...

Auf dem Gelände eines kleinen chemischen Betriebs (Monor, Ungarn) hat die illegale Deponierung von Müll zu einer starken Verunreinigung des Grundwassers mit Chrom(VI)— Verbindungen geführt. Nachdem die Quelle der Verunreinigung beseitigt war, gab das ungarische Ministerium für Umweltschutz und Wasserwesen eine Untersuchung in Auftrag, deren Ziel es...

Aluminium- and iron(III) salts have been used as coagulants in the coagulation-flocculation processes, which play an essential role in the treatment of surface waters. Hydrolysis causes the aforementioned metal salts to transform into metal hydroxides, the particles of which aggregate into floes accessible to sedimentation and filtration, i.e., to...

Illegal wastes disposal caused heavy groundwater pollution with Cr(VI) compounds on the premises of a small chemical operation (Monor, Hungary). Once the source of the pollution hazard was removed, the Hungarian Ministry of Environmental Protection and Water Management has ordered a survey to be run with the aim of assessing the severity and extent...

The removal of five different heavy metals (Zn2+, Cu2+, Cr 3+,Cd 2+ and Ni 2+) was studied under laboratory conditions using close to neutral mixed municipal wastewater. 90 to 95 % of the Zn2+, Cu2+ and Cr3+ was found to precipitate within 5 min and to become removable by simple phase separation. The Cd2+ and Ni2+, however, refused to precipitate,...

Nitrate-concentration above a permitted level is a problem in several countries. To reduce nitrate-concentration, a number of processes had been invented. Nevertheless, non of them is considered best, and the search for other methods or a further development thereof is regarded most desirable. The research work - presented in this report - was init...

In Hungary, the damages in soil and vegetation are presently in some regions the hallmarks of an accelerating process in acidification of the environment. Because of the geological and hydrogeological characteristics of Hungary, one cannot discover permanent acidification, at the time being, in available surface and subsurface water resources. The...

It has been established in laboratory model experiments that the removal of dissolved heavyimetals from wastewaters is rendered more difficult in the presence of colloid-stabilizing agents. This unfavourable effect can be eliminated by the addition of Mg2+ ions and the adjustment to a fairly high pH. By increasing the concentration of Mg2+ ions, th...

One of the most serious water quality problems of our age is the growing heavy metal content of our surface waters. Heavy metals are present in the water in dissolved and in stable phases. Dissolved heavy metals may change into solid material. This latter can be settled on the bottom, then may undergo another change and may return in the water in e...

A mathematical model was elaborated by the authors for the description of the behavior of dissolved and solid cadmium in the Sajo river. The model is based on transport-equations supplemented by transitions between dissolved and stable phases and has three state variables - concentration in dissolved state, concentration in stable state, and volume...

A series of experiments is described, in which the optimal pH range in clarification, as well as the conditions affecting the interactions between the flocs and the dispergated colloidal particles were investigated. These experiments were carried out using a natural colloidal dispersion: the water of the River Danube. In the experiments the Zeta-po...