High CODcr Research Articles

Photoelectrocatalytic degradation of wastewater and simultaneous synthesis of NH3 on Fe-CNTs-supported octahedral Cu2O composite nanocatalysts

Fe-core carbon nanotubes (Fe-CNTs) were produced by vapor deposition using coal as a carbon source. Then, octahedral copper oxide nanoparticles (Cu2ONO) (prepared by solvent reduction method) were loaded on Fe-CNTs by hydrothermal method to prepare the composite catalyst Cu2ONO/Fe-CNTs. While characterizing (TEM, XRD, FTIR, XPS, N2-TPD, BET, etc.) the material structure, the performance of Cu2ONO/Fe-CNTs in photoelectrocatalytic (PEC) degradation of cotton pulp black liquor (CPBL an organic wastewater with high CODCr) and simultaneous synthesis of NH3 was studied. The PEC reaction was carried out in an H-type reactor. CPBL was oxidized at the anode to produce H+, CO2, H2O and other small molecules, where H+ passes through a proton exchange membrane and is reduced with N2 to produce NH3 at the cathode. After 4 h of reaction, the CODCr removal rate of CPBL in the anode chamber reached 95.42%, and the yield of NH3 in the cathode chamber reached 9.06 mmol L−1 cm−2. The dual purpose of synthesizing NH3 while degrading wastewater was achieved.

Effect of pH shock on the treatment of high concentration organic wastewater via a Fe0/GO-anaerobic system

The pH is one of the key factors affecting microbial activity in anaerobic systems. In this paper, the pH impact tolerance of Fe0/GO (zero-valent iron/graphene oxide) mediated anaerobic treatment system for high concentration organic wastewater was studied. The effects of a Fe0/GO mediated anaerobic system on wastewater treatment, degradation kinetics, and the physicochemical properties of sludge were studied at pHs of 5.5 and 8.5; the separate addition of Fe0 and GO and a blank system were used as the blank control. The results showed that the pH had adverse effects on the treatment of each system and the physicochemical characteristics of sludge. However, the Fe0/GO system under pH shock maintained a relatively high CODCr removal rate and gas production; the effluent volatile fatty acid content was the lowest, the effluent pH value deviation from the normal range was small, the degradation rate constant, and sludge concentration and flocculation performance of the mixed liquid were better than those of other systems. The recovery phase of Fe0/GO returned to normal in a relatively short time. These results showed that adding Fe0/GO to the anaerobic treatment of high concentration organic wastewater system can drastically improve the pH shock resistance of the system.

Process Optimization and Characterization of Copper Oxide/Zeolite for Heterogeneous Catalytic Wet Oxidation of Dyeing Wastewater

Waste coal fly ash was used, as a cheap and handy material, to synthesize zeolite.The synthesized zeolite was then taken, as a carrier, to load CuO by dipping method for heterogeneous catalytic wet oxidation of acid bright red GR wastewater. The optimal process parameters of CuO loading were determined by orthogonal test. The comparison of XRD patterns of zeolite and CuO/zeolite displayed that CuO was successfully loaded on the zeolite.The SEM morphology of CuO/zeolite revealed that the cotton shape structure with more loose surface of CuO/zeolite was obtained compared with the SEM morphologies of fly ash and synthesized zeolite. The experimental results of water treatment showed that high CODCr and chroma removal rates of 88.27% and 99.97% were achieved by the prepared CuO/zeolite sample,respectively.

Process Modeling of CuO/Zeolite Preparation for COD<sub>C</sub><sub>r </sub>Removal from Acid Bright Red GR Wastewater

The study on CuO/zeolite preparation for CODr removal from acid bright red GR wastewater was carried out. The optimal process parameters,with zeolite/copper nitrate solution ratio of 1:4 g/mL, copper nitrate solution concentration of 1.0mol/L, calcining temperature of 400°Cand calcining time of 5 h, were determined by single test method .The CuO/zeolite prepared under the optimal conditions obtained high CODCr and chroma removal rates with more than 87%and 99,9%,respectively.The process model of CuO/zeolite preparation was established by response surface methodology. The model was proved to be reliable and accurate and its theoretical values were very close to the the actual test values with absolute relative errors ranged from 0.00% to 1.49%, which can be used to predict, adjust and control the process conditions of CuO/zeolite preparation for getting desired CODCr removal rate.

Study on Improving Biodegradability of Straw Pulp Papermaking Wastewater by Coagu-Flocculation and Nuclear-Flocculation

When straw pulp papermaking wastewater was treated by the process of coagu-flocculation and nuclear-flocculation, there were still high CODCr. UV254 can reflect organic pollutants and organic pollutants of unsaturated aromatic ring, carbon-carbon double bond. With the decrease of molecular weight of organic pollutants, absorption of ultraviolet light will decrease. Indirectly, it reflectd that the combination process had a good removal effect on high molecular aromatic hydrocarbons difficult to be biodegraded. Meanwhile it can improve the the biodegradability. It used the activated sludge process as subsequent process of coagulation and-flocculation process. The test results showed that the removal rate of CODCr was 24.1%, CODCr was the 88.1mg/L. It reached effluent standard.

Eco-physiological characteristics of Pistia stratiotes and its removal of pollutants from livestock wastewater.

The effectiveness of water lettuce in removing pollutants including organic pollutants, nitrogen (NH3-N) and total phosphorus (TP) from livestock wastewater along with the physiological effects and their correlations, was studied for the first time. The results showed that the water lettuce had higher removal efficiency with low concentrations of livestock wastewater. The removal efficiency of water lettuce for different initial concentrations of livestock wastewater within 8 d was as follows: chemical oxygen demand (CODcr) (68-82%) > NH3-N (57-69%) >TP (27-45%). The speed of purification of water lettuce for CODcr, NH3-N and TP conformed to first order kinetics equations. The water quality indices CODcr, NH3-N and TP had a higher linear correlation with peroxidase (POD) activity (R(2) > 0.9(2)) than with superoxide dismutase (SOD) and catalase (CAT) activity, which indicates that the main reacting enzyme of water lettuce under high CODcr stress is peroxidase.

Mechanism Analysis of Coagu-Flocculation and Nuclear-Flocculation Combined Process Treat on Straw Pulp Papermaking Wastewater

There were still high CODCr in straw pulp papermaking waste water, which was dealed with coagulation-combination with nuclear flocculation process. To explore its causes, according to organic qualitative analysis results by GC-MS of the coagulation-flocculation with nuclear process on wastewater treatment and biochemical analysis, this study did the mechanism analysis to the process. It was the main reason, why caused high CODcr, to remain small molecules organic contaminants in the water, such as phthalic acid mono-2-ethylhexyl ester and Diisobutyl phthalate.

Experimental Study on High Salt Acid Pretreatment of Refinery Wastewater

We pretreat the high salt level, high CODcr and strong acid refinery wastewater and analyse the influence of the iron-carbon ratio and the pH to ferric-carbon micro-electrolysis. Thereby we confirmed the reaction time and mixture component. Furthemore, we discussed the influence of supersaturated sodium on ferric-carbon micro-electrolysis. The results show that ferric-carbon micro-electrolysis can take full advantage of high salt, strongly acidic water quality characteristics of refinery wastewater to confirm that the removal rate of CODcr can reach to 49%, at the conditions of the iron-carbon ratio of 1:1, micro-electrolysis time is 45 minutes and the pH rise to 8 by lime milk. In addition, the decoloring effect is remarkable.

Degradation of Disperse Blue 2BLN Dye Wastewater by Pulsed Corona Discharge Combined with Ozone Process

Waste water discharged from dye plant contains high sanity ,high chroma and high CODcr (Chemical Oxygen Demand), commonly used biodegradation is often limited in application; As a new efficient advanced oxidation, pulsed corona discharge combining with ozone is attracting more and more attention. A special reactor was designed, in addition, the removal of COD and decoloration of stimulant dye wastewater containing disperse blue 2BLN dye (100mg/L) by pulsed corona discharge combining with ozone were investigated . It showed that in alkaline solution, the maximum COD removal and decoloration rate(58.8% and 99.1%) was observed ,which demonstrated that ozone and pulsed discharge was more efficient on COD removal and decolouration in alkalin than in neutral solution when all the samples were treated for13mins. After being treated, B/C increased from 0.2 to 0.45. Decoloration efficiency and COD removal could be improved obviously when oxygen feed increased from 40 to80L /h，yet further increase in oxygen feed led to a markedly decrease of decolouration efficiency and COD removal.

Engineering Example of High Concentration Printing and Dyeing Wastewater Processed by UBF Craft

The multi-methods of UBF-biological contact oxidation - enhanced coagulation- precipitation - fiber sand filtration has been applied to treatment a dyeing and printing wastewater, because it is with the characteristics of large flow, high CODcr, high chromaticity and toxic substances. The result showed: when the feed wate under the conditions of CODcr, BOD5, SS quality concentrations were 15000mg / L, 250mg / L,> 800mg / L and chromaticity blow 1000 times, effluent water quality can meet grade one of the national integrated wastewater discharge standards (GB8978-1996).

Natural wastewater treatment in Hungary

Over the last few decades more and more natural wastewater treatment systems have been built in Hungary. The present study is the first step in creating a broad database on the water quality parameters and on the pollutant removal efficiency of these systems. The investigation included 78 plants out of which we analysed 16 systems in detail. Four types of natural methods are evaluated: wetlands, ponds, biomechanical combined oxidation (BMKO) systems, and poplar plantations. Pond systems are efficient in ammonium-nitrogen (NH4-N) removal, reducing it with 83% (41-88%). Their chemical oxygen demand (COD(Cr)) removal capacity is only 55% (37-81%). The only BMKO system that could be evaluated performs high COD(Cr) (77%) and total suspended solid (TSS) (89%) removal. Removal of NH4-N and total nitrogen (TN) declines during the years of operation giving an average value of 39% and 49%, respectively. The system is not efficient in phosphorus removal (13%). In wetlands the 71% COD(Cr) (53-96%), and 57% TSS (33-91%) removal provides satisfactory effluent quality most of the time. Wetlands performed low nutrient removal, i.e., 17% (-21-46%) for TN and 26% (-20-92%) for phosphorus. Poplar plantations are very effective in pollutant removal. Even the average removal of each nutrient type is above 75%. Several problems have occurred in the operation of natural treatment systems. However, if carefully planned and constructed, and the required maintenance work is done properly, they can be possible alternatives for wastewater treatment.