Conference Papers

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Activated algae granulation: A biological solution for efficient microalgae harvesting

(2015)
Tiron, Olga
;
Bumbac, Costel
;
Patroescu, Viorel Ion
;
Stefanescu, Mihai
A novel biological method was developed as an alternative solution for the major drawback in developing the microalgae biotechnology for wastewater treatment at industrial scale: the microalgae harvesting step. The method allows efficient and fast harvesting of target microalgae cells (such as Chlorella sp.) and consists in the granulation of the photoautotrophic microalgae – bacteria biomass, in a stirred tank photo-bioreactor with specific operational conditions, using real wastewater as growth medium. Granulation process requires the presence of the filamentous microalgae which represent the base matrix of the biological structure. During the development of the granular entities, termed as activated algae granules, target microalgae cells are efficiently entrapped in the granular structure, thus almost complete microalgae biomass recovery (99.15–99.99%) is ensured by granules settling only. Moreover, high density of the biomass within the granule’s structure (with 80–300 ug dry weight/granule) and large granules’ size (500–3000 um) ensure a high settling velocity of the granules (18–29 m/h) which is higher with about 3–5 × 103 times than that of individual Chlorella sp. cells. Such performances prove the viability of the granular activated algae system by sustaining a cost saving microalgae harvesting strategy for the development of a new generation biotechnology for wastewater treatment.
4 166
Aerobic granular sludge in a sequencing batch reactor

(2015)
Ionescu, Ioana
;
Bumbac, Costel
;
Cornea, Petruta Calina
Granular sludge consist of bacterial aggregates that are much more compact than traditional activated sludge, thus offering numerous advantages such as high biomass retention, good settling ability and simultaneous removal of organic load and nutrients. In a laboratory scale sequencing batch reactor (SBR) granules were cultured under aerobic conditions. To enhance the growth of granular sludge the SBR was operated with very short sedimentation and draw phases resulting in the washout of slow settling biomass (anaerobic feeding – 45 min, aerobic reaction – 11 h, settling – 5 min and effluent withdrawal – 10 min). The reactor was inoculated with conventional activated sludge and fed with dairy industry wastewater with high organic and nutrients load. The first aerobic granular structures, having 67–556 m in diameter, were observed after 5 days. After 25 days, they reached diameters between 513 m and 1276 m and increased gradually up to diameters of 2 mm by the end of the experiment. Treatment performances increased along with the growth of granules size.
1 114
Aerobic granular sludge reactors flow optimization towards continuous flow systems

(University of Washington - Rome Center (UWRC) , 2020-06)
Manea, Elena Elisabeta
;
Bumbac, Costel
2 110
Aerobic granular sludge – Microbial and morphological characterization

(2016)
Ionescu, Ioana
;
Bumbac, Costel
;
Nita-Lazar, Mihai
Biological wastewater treatment processes have a crucial importance to the modern world, due to the ever increasing need of sanitation and pollution control in urbanized areas. Aerobic granular sludge represents an alternative for the conventional biological system. Recent studies have greatly expanded the vision on aerobic granular sludge morpho-functional and microbiological peculiarities and their influence on wastewater treatment performance and behavior. The microbial composition of the granules obtained in a sequencing batch reactor – SBR, were characterized using microscopy and molecular biology techniques. Scanning electron microscopy investigations,revealed in sights into the granules morphology and structure: size, pore dimensions, presence of filamentous bacteria. Molecular biology techniques were used to determine the presence and abundance of biotechnologically useful bacteria (nitrifiers, denitrifiers) in the sludge granules samples. The samples were subjected to PCR amplification using the following primers: specific for ammonium oxidizing bacteria; specific for nitrite oxidizing bacteria; universal bacteria primers. The results indicated the presence of nitrifying bacteria specific genes belonging to Nitrosomonas sp., Nitrospira sp., and Nitrobacter sp., species responsible for nitrification. The abundance and diversity of identified microbial species were correlated with the treatment performances registered for the operational sequencing batch reactor.
3 156
Anionic surfactants oxidation using AOPs and a novel “IN-FOAM UV/AIR OXIDATION” process

(2010)
Dinu, Laurentiu Razvan
;
Stoica, Ligia
;
Nitoi, Ines
;
Bumbac, Costel
;
Patroescu, Viorel Ion
;
Moise, Andreea
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.
2 122
Anionic surfactants oxidation using aops and a novel “in-foam uv/air oxidation” process

(2007)
Dinu, Laurentiu Razvan
;
Stoica, Ligia
;
Nitoi, Ines
;
Bumbac, Costel
;
Patroescu, Viorel Ion
;
Moise, Andreea
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.
3 49
Application of adsorption matrices consisting of mixed biomass resulting from wastewater treatment processes for the removal of Zinc and Nickel metals

(2024)
Buse, Tatiana
;
Tiron, Olga
;
Ionescu, Ioana
;
Dinu, Laurentiu Razvan
;
Badescu, Valeriu
30 51
Applying of photolitic processes in advenced degradation of some xenobiotics from municipal wastewater

(2007)
Stefanescu, Mihai
;
Nitoi, Ines
;
Nicolau, Margareta
;
Pena-Leonte, Eliza
;
Cosma, Cristiana
;
Ballo, Aureliea
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.
9 113
Ard treatment - batch vs. Continuous flow reaction systems for sulphate precipitation, a technical note

(SGEM WORLD SCIENCE , 2017)
Dinu, Laurentiu Razvan
;
Balaiu, Ioan
;
Cristea, Ionut
;
Badescu, Valeriu
;
Dediu, Violeta
Sulphate is the specific anion present in the acid rock drainage (ARD). Although sulphate is considered benign or with low toxicity, some countries have set limits for the wastewater discharged to natural receivers, often 500 mg/L or 600 mg/L. By conventional treatment of the ARD with calcium hydroxide, some gypsum can precipitate, depending on the ARD initial sulphate content, but the conformity for sulphate will not be achieved, because the concentration correlated to gypsum solubility exceeds the limit value by roughly three times. An experimental study has been carried out to assess sulphate precipitation via ettringite process from acid rock drainage originating from closed non-ferrous mine site in the North Romanian mining area. Tests for sulphate precipitation, using monocalcium aluminate cement as source of reactive aluminium for the ettringite formation, showed important differences regarding sulphate precipitation yield between batch and continuous flow reaction systems, due to reaction system itself. For continuous stirred tank reactor system (CSTR) a total space-time of 2.6 h is required when operating with cement dose equivalent to 265 mg Al for 1 g sulphate in order to safe meet the sulphate discharge limit of 600 mg/L for mine water with initial c(SO42-) = 2650 mg/L and at a temperature of 15 oC.
1
Bacterial adhesion on a newly designed soap film

(2024)
Stoica, Catalina
;
Banciu, Alina
;
Nita-Lazar, Mihai
3 46
Bioindicators of community structure in microalgae-bacteria processes

(2016)
Tiron, Olga
;
Bumbac, Costel
For many decades, microalgae biomass has been representing a valuable resource for anthropic ecosystems. An important step was achieved in microalgae-based technologies field once with finding that relationship established between microalgae and activated sludge could revolutionize conventional wastewater treatment systems, with establishment of the sustainable treatment strategies. In conventional activated sludge processes, protozoan species represent indicators of the operating conditions and treatment performance. However, low level of knowledge was found to be addressed to bioindicators in microalgae-bacteria processes. Thus, the study focused on investigating protozoa dynamics during low strength wastewater treatment using microalgae-bacteria system. Experiments were performed using a photobioreactor operated in sequential batch operation mode. During the first treatment batches, protozoan community was characterized by a high species richness represented by ciliates and testate amoebae, small free swimming ciliates being the prevalent taxa- diversity comparable with that reported in the early stage of the activated sludge development. A transition stage of the protozoan community followed once with biomass development, the disappearance of testate amoeba and development of stalked ciliates populations being noticed. However, a reduction of species richness was recorded after transition stage, a tendency that has led to a complete elimination of the protozoan community. Taking into consideration operating conditions, it was concluded that microalgae-bacteria processes are different from those of activated sludge regarding protozoan community structure. However, microalgae-bacteria processes sustained the development of metazoan community, a high abundance of rotifers populations being recorded at the end of experiments.
2 87
Biological treatability of domestic and industrial wastewaters in a treatment plant

(2012)
Masu, Smaranda
;
Jurj, Nicoleta Luminita
;
Murariu, Marcel
;
Savescu, Elena
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.
15 92
Biosorption of Metal Ions Co (II) and Zn (II) from Aqueous Media Using Biochar Obtained from Algae Biomass

(University Politehnica Bucharest , 2022-09)
Ciobanu, Alina Alexandra
;
Munteanu, Loredana
;
Bulgariu, Laura
;
Vasile, Gabriela
8 82
Break-point chlorination drawbacks for a complex impurified groundwater sources (NH4, Fe, Mn) potabilization treatment

(University Politehnica Bucharest , 2018-09)
Cosma, Cristiana
;
Patroescu, Viorel Ion
;
Ionescu, Ioana
;
Cristea, Ionut
;
Constantin, Mirela Alina
2 64
Combined ultrasonic and alkaline pretreatment method of wastewater treatment plant sludge for the improvement of biogas production by anaerobic fermentation

(U.T.PRESS , 2018)
Stefanescu, Mihai
;
Bumbac, Costel
;
Dinu, Laurentiu Razvan
;
Cosma, Cristiana
;
Patroescu, Viorel Ion
16 51
Comparison of three metal doped titanium dioxide photo-catalysts performances for treatment of municipal wastewater under simulated solarlight

(2024)
Constantinov, Florenta Daniela
;
Nechifor, Gheorghe
;
Constantin, Lucian Alexandru
14 71
Considerații privind reactivitatea incarcarii organice naturale fata de clor din surse subterane tratatei sistem biologic pentru biooxidare ioni amoniu

(2014)
Cosma, Cristiana
;
Patroescu, Viorel Ion
;
Alexie, Mihaela
;
Bumbac, Costel
;
Tiron, Olga
;
Cristea, Ionut
The presence of inorganic compounds containing oxidable nitrogen within groundwater sources at various,high concentration levels, especially in the case of NH+4 (NH+4 ≤ 8 mg/l), is asking for the replacement of classical oxidation technology using “break point” chlorination, due to non-conformities generated by high consumptions of chlorogenic agents (tens mg Cl2/l) upon the quality of treated water (acid pH, high ratio of residual bound chlorine, trihalomethans above the maximum admissible concentration). Biochemical oxidation using a bio-filter system in specific operating conditions (media type, temperature, oxygen demand, inorganic carbon and phosphorus sources, biological contact time, etc.) is representing a feasible technological alternative. Taking into account that carbon source used within the biochemical process is inorganic, the dissolved natural organic matters (NOM- humic matters) can react with the chlorine used in the final stage of biological effluent treatment. In the conditions of advanced removal of NH+ 4, oxidation to NO- 3, the chlorine dosages needed for effluent‟s finishing, disinfection are reduced. Experimental tests have as objectives to set up the chlorine dosage (Cl2 = 0,5 † 0,8 mg/l) that assures the disinfection of effluents resulted from biological nitrification step and a minimum ratio of residual bound chlorine, as well as the assessment of trihalomethanes formation potential in case of dissolved organic load, DOC ≤ 1,8 mg C/l (weight rations Cl2 / DOC = 1 † 8).
45 7
Crude oil polluted soils phytoremediation with native grass

(2014)
Masu, Smaranda
;
Marin, Anca Andreea
;
Lixandru, Benoni
;
Popescu, Dumitru
;
Ciulan, Valentin
;
Morariu, Florica
;
Morariu, Sorin
Phytoremediation of soil contaminated with petroleum products is a technology that can restore of damaged soil. The use of recyclable materials such as stabilized municipal sludge stimulates the plant growth on crude oil polluted land is a simple joint sustainable waste management. Besides the nutrient deficient polluted soils, sewage sludge brings biocenosis to improve the destroyed soil bacterial community. To identify plant species that increase the degree of remediation of polluted soils with 6.4% total petroleum hydrocarbons two species of native wild plants Hordeum murinum and Cynodon dactylon have been investigated. Polluted soil treatment was performed with 25 t/ha stabilized sewage sludge in the absence/presence of 2 t/ha indigenous volcanic tuff. The implication of the finding of the vegetable cover studies is that 120 days growth of plants can lead to cleanup of crude oil polluted and fertilized soils and reduction of pollution level at 20 cm depth with 55% for Hordeum spp. and with 65% for Cynodon spp. Addition of tuff mixed with sewage sludge increased reduction of crude oil to 60% for Hordeum spp. and 76% for Cynodon spp. The tolerance and adaptability of plants in polluted soil makes each of these species a tool for the remediation-polluted soils.
9 107
Cyclic voltammetry tool for assessing electrochemical degradation of diclofenac

(2014)
Ihos, Monica
;
Manea, Florica
;
Pode, Rodica
The cyclic voltammetry (CV) experiments were carried out in order to assess the electrochemical degradation of diclofenac (DCF) at dimensionally stable anodes (DSA). The working electrode was a boron-doped diamond (BDD) electrode and electrolysed solutions of DCF in 0.1 M Na2SO4 supporting electrolyte were used. The electrolysed solutions were obtained previously in the electrochemical degradation of DCF at DSA electrodes, Ti/RuO2-TiO2 and Ti/RuO2/SnO2-Sb2O5-RuO2, at various current densities and 120 minutes of electrolysis. The peak current abatement efficiency was calculated based on cyclic voltammograms (CVs) and the most efficient composition of DSA for DCF degradation was designated.
2 57
Degradation of piroxicam by electrochemical oxidation at DSA electrodes

(2014)
Ihos, Monica
;
Manea, Florica
;
Pode, Rodica
The presence of pharmaceuticals in water is undesirable because of their adverse effects on aquatic organisms even in concentration of ng-µg/L. This paper dealt with the degradation of piroxicam (PXC), a nonsteroidal anti-inflammatory drug (NSAID), by electrochemical oxidation at dimensionally stable anodes (DSA). Two compositions of DSA were used: Ti/RuO2-TiO2 and Ti/RuO2/SnO2-Sb2O5-RuO2. Current densities of 200 and 300 A/m2 were applied for electrolyses time of 60, 120 and 180 minutes in neutral or basic medium. The ultraviolet (UV) spectra of the electrolysed solutions were recorded and total organic carbon (TOC) analyses were carried out to assess the degradation process. The most effective in degradation of PXC was the anodic composition Ti/RuO2-TiO2 in basic medium.
1 81

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