Construction of hybrid cell with Phanerochaete chrysosporium to degrade terephthalic acid wastewater——(I) phenotype evidence

The fungi Phanerochaete chrysosporium (PC) and Saccharomyces cerevisiae Y99 and the native bacterium YZ1 were the three parental strains for construction of hybrid cells through protoplast fusion to degrade terephthalic acid (TPA) wastewater. The results showed that the native bacterium YZ1 protoplasm could integrate with that of PC to form the hybrid cell Fhh and the fungus Y99 protoplasm also could integrate with that of Fhh to form the hybrid cell Fhhh. The protoplasts of YZ1 and Y99 could change the morphology of PC spore and mycelium for two times. The hybrid cell Fhhh got the best growth and degradation abilities in the wastewater. It suggested that the hybrid strains obtained from the inter\|kingdom protoplast fusion of the three parental strains could create potential for the purification of TPA wastewater.

A binder-free electrode for efficient H_(2)O_(2) formation and Fe2+ regeneration and its application to an electro-Fenton process for removing organics in iron-laden acid wastewater

The electro-Fenton process,with its capacity for in-situ H_(2)O_(2)formation and Fe^(2+)regeneration,is a strik-ing alternative to the traditional chemical-Fenton process.However,the frequent requirement of extra binders for electrode fabrication leads to low catalyst utilization,a complex fabrication process,and weak conductivity.Herein,a three-dimensional(3D)porous electrode was fabricated in-situ on a Ni foam(NF)substrate integrated with nitrogen-doped carbon nanotubes(N@C)derived from carbonization of zeolitic imidazolate framework-8(ZIF-8)without any binder.The resulting 900/N@C-NF cathode(synthesized at 900℃)was high in surface area,N content,and degree of graphitization,achieved high performance of H_(2)O_(2)production(2.58 mg L^(−1)h^(−1)H_(2)O_(2)/mg catalyst)at-0.7 V(vs.SCE),and enabled prompt regeneration of Fe^(2+).The electro-Fenton system equipped with the 900/N@C-NF cathode was effective in removing a diverse range of organic pollutants,including rhodamine B(Rh B),phenol,bisphenol A(BPA),nitroben-zene(NB),and Cu-ethylenediaminetetraacetic acid(EDTA),and significantly attenuating the concentration of chemical oxygen demand(COD)in the real acid wastewater,exhibiting superior activity and stability.This binder-free and self-supporting electro-Fenton cathode was thus shown to be an attractive candidate for application to wastewater treatment,particularly those rich in organics,acids,and Fe^(3+)/Fe^(2+).

Membrane bioreactor process of organic wastewater from brassylic acid manufacturing plant

The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluation tank. The content of test included the affection of variation operation conditions on ultrafiltration separation, the general characteristics of MBR process, and the difference comparing with the conventional biological treatment. The results are as follows: (1) among the test membrane material, polyether sulphone (PES) membrane is more suitable for the wastewater treatment; (2) when the cutoff molecular weight is among 10000-50000, the higher the cutoff molecular weight, the bigger the water flux is in the test; (3) under the operation pressure, water flux increases accompanying with the increasing of operation pressure; (4) the paper filtered COD concentration has more affection on the water flux than the suspended solid concentration; ( 5) as they volume loading of MBR increases, the accumulation of high molecule organic substance and colloid increases, the membrane,permeate COD concentration and paper filtered COD concentration increase too, meanwhile the water flux reduces; (6) when the sludge retention time of activated sludge of MBR increases, the accumulation of high molecule organic substance and colloid reduces, the membrane permeate (:OD concentration and paper filtered COD concentration reduce too, and the water flux increases; (7) comparing with the conventional biological process, the microbial activity is higher, but the microbial species is less.

Predication of Fhhh potential in PTA wastewater treatment

Ebis is the intelligent environmental biotechnological informatics software developed for judging the effectiveness of the microorganism strain in the industrial wastewater treatment system(IWTS) at the optimal status. The parameter, as the objective function for the judgment, is the minimum reactor volume( V _ min ) calculated by Ebis for microorganism required in wastewater treatment. The rationality and the universality of Ebis were demonstrated in the domestic sewage treatment system(DSTS) with the data published in USA and China at first,then Fhhh strain's potential for treating the purified terephthalic acid(PTA) was proved. It suggests that Ebis would be useful and universal for predicating the technique effectiveness in both DSTS and IWTS.

Selective recovery of Cu(II) from strongly acidic wastewater by zinc dimethyldithiocarbamate: Affecting factors, efficiency and mechanism

The selective recovery of copper from strongly acidic wastewater containing mixed metal ions remains a significant challenge.In this study,a novel reagent zinc dimethyldithiocarbamate(Zn(DMDC)_(2))was developed for the selective removal of Cu(II).The removal efficiency of Cu(II)reached 99.6%after 120 min reaction at 30°C when the mole ratio Zn(DMDC)_(2)/Cu(II)was 1:1.The mechanism investigation indicates that the Cu(DMDC)_(2) products formed as a result of the displacement of Zn(II)from the added Zn(DMDC)_(2) by Cu(II)in wastewater,due to the formation of stronger coordination bonds between Cu(II)and the dithiocarbamate groups of Zn(DMDC)_(2).Subsequently,we put forward an innovative process of resource recovery for strongly acidicwastewater.Firstly,the selective removal of Cu(II)fromactualwastewater using Zn(DMDC)_(2),with a removal efficiency of 99.7%.Secondly,high-value CuO was recovered by calcining the Cu(DMDC)_(2) at 800°C,with a copper recovery efficiency of 98.3%.Moreover,the residual As(III)and Cd(II)were removed by introducing H_(2)S gas,and the purified acidic wastewater was used to dissolve ZnO for preparation of valuable ZnSO_(4)·H_(2)O.The total economic benefit of resource recovery is estimated to be 11.54$/m^(3).Accordingly,this study provides a new route for the resource recovery of the treatment of copper-containing acidic wastewater.

Experimental Study on Formation Conditions of Ammoniojarosite and Its Environmental Significance

Formation conditions of ammoniojarosite in system Fe2（SO4）3-（NH4）2SO4-H2O are investigated in this paper. The results show that ammoniojarosite can be formed rapidly under normal temperature and pressure by controlling suitable pH value and Fe2（SO4）3 and （NH4）2SO4 concentrations. The pH value, temperature and concentration of Fe2（SO4）3 medium are key factors influencing the formation of ammoniojarosite. Under normal temperature, precipitation of ammoniojarosite can be seen within 24 hours at pH values between 2.6-3.1, and a great quantity of ammoniojarosite is formed within 48 hours. At about 90℃, the pH value range forming ammoniojarosite extends to 1.2-3.1, and within this range the rise of pH value is advantageous to the formation of ammoniojarosite and high Fe2（SO4）3 concentration is also advantageous. Relative pure ammoniojarosite is synthesized under high Fe2（SO4）3 concentration （≥0.05 M） and ammoniojarosite containing melanterite and colloid amorphous hydroxide vitriol iron is formed at low Fe2（SO4）3 concentration. The deposition process of ammoniojarosite can be used to harness wastewater from mines and other industries and remove S, Fe and other toxic and harmful elements, such as As, Cr, Hg, Pb in water. Rapid formation of ammoniojarosite and other jarosite analogs under normal temperature and pressure has a good potential prospect for harnessing acid wastewater by means of precipitation of jarosite and its analogs.

Characteristic of synergistic extraction of oxalic acid with system from rare earth metallurgical wastewater

Large amount of high concentration acidic wastewater would be produced in the conversion process of chloride rare earth into oxide rare earth. It was a mixed solution of oxalic acid and hydrochloric acid, so the recycling use was very difficult. The method of liquid-liquid extraction was proposed in this paper to achieve wastewater treatment and reclamation. The mechanism of extraction of oxalic acid from the wastewater with the systems of 50% TOB+45% kerosene and 5% 2-ethyl hexanol was investigated. The composition and structure of the extracted species and the establishment of the mathematical model of the oxalic acid extraction were determined by the use of saturation method, equimolar series method. The results showed that extraction of oxalic acid by TOB was a neutral association extraction, oxalic acid existed mainly in a molecular form in the organic phase, and the extraction combination ratio was 2:1. The duality extraction system composed of extractant TOB and TOC had synergistic extraction effect on oxalic acid and chlorhydric acid, and the extraction distribution ratio was improved greatly. The optimum volume fraction of TOB was 0.6-0.8.

Removal of Ni(Ⅱ) from strongly acidic wastewater by chelating precipitation and recovery of NiO from the precipitates

Strongly acidic wastewater produced in nonferrous metal smelting industries often contains high concentrations of Ni(Ⅱ), which is a valuable metal. In this study, the precipitation of Ni(Ⅱ) from strongly acidic wastewater using sodium dimethyldithiocarbamate(DDTC) as the precipitant was evaluated. The effects of various factors on precipitation were investigated, and the precipitation mechanism was also identified. Finally, the nickel in the precipitates was recovered following a pyrometallurgical method. The results show that, under optimised conditions(DDTC:Ni(Ⅱ) molar ratio = 4:1;temperature = 25 ℃), the Ni(Ⅱ) removal efficiency reached 99.3% after 10 min. In strongly acidic wastewater, the dithiocarbamate group of DDTC can react with Ni(Ⅱ) to form DDTC –Ni precipitates. Further recovery experiments revealed that high-purity Ni O can be obtained by the calcination of DDTC –Ni precipitates, with the nickel recovery efficiency reaching 98.2%. The gas released during the calcination process was composed of NO_(2), CS_(2), H_(2)O, CO_(2), and SO_(2). These results provide a basis for an effective Ni(Ⅱ) recovery method from strongly acidic wastewater.

Clean and effective removal of Cl(-I)from strongly acidic wastewater by PbO_(2)

Recycling strongly acidic wastewater as diluted H_(2)SO_(4) after contaminants contained being removed was previously proposed,however,Cl(-I),a kind of contaminant contained in strongly acidic wastewater,is difficult to remove,which severely degrades the quality of recycled H_(2)SO_(4).In this study,the removal of Cl(-I)using PbO_(2) was investigated and the involved mechanisms were explored.The removal efficiency of Cl(-I)reached 93.38%at 50℃ when PbO_(2)/Cl(-I)mole ratio reached 2:1.The identification of reaction products shows that Cl(-I)was oxidized to Cl_(2),and PbO_(2) was reduced to PbSO_(4).Cl_(2) was absorbed by NaOH to form NaClO,which was used for the regeneration of PbO_(2) from the generated PbSO_(4).Cl(-I)was removed through two pathways,i.e.,surface oxidation and•OH radical oxidation.•OH generated by the reaction of PbO_(2) and OH−plays an important role in Cl(-I)removal.The regenerated PbO_(2) had excellent performance to remove Cl(-I)after six-time regeneration.This study provided an in-depth understanding on the effective removal of Cl(-I)by the oxidation method.

Solar active fire clay based hetero-Fenton catalyst over a wide pH range for degradation of Acid Violet 7

Fe（III） immobilized fire clay （Fe-FC） was prepared using ferric nitrate by solid state dispersion method and this hetero-Fenton catalyst was applied for the degradation of Acid Violet 7 （AV 7） under natural sunlight. The 26% ferric nitrate loaded fire clay was found to be most efficient. The experimental conditions such as solution pH, H2O2 concentration for efficient degradation of AV 7 have been determined. Unlike Fenton catalyst, Fe-FC is photoactive over a wide pH range of 3-7. This catalyst was found to be stable and reusable. The GC-MS analysis of experimental solutions during irradiation revealed the formation of 2,8-diaminonaphthalene-1,3,6- triol, 8-aminonaphthalene-1,2,3,6-tetrol, 2-aminonaphthalene-1,3,6,8-tetrol and 2-aminobenzene-1,3-diol/5-aminonbenzene-1,3-diol/ 2-aminobenzene-1,4-diol as intermediates. The 26% ferric nitrate loaded fire clay was characterized by XRD, ICP-AES, BET surface area, FT-IR, SEM-EDS and UV-DRS studies.

Systematic control technologies for gaseous pollutants from non-ferrous metallurgy

Air pollutant emissions represent a critical challenge in the green development of the non-ferrous metallurgy industry.This work studied the emission characteristics,formation mechanisms,phase transformation and separation of typical air pollutants,such as heavy metal particles,mercury,sulfur oxides and fluoride,during non-ferrous smelting.A series of purification technologies,including optimization of the furnace throat and hightemperature discharge,were developed to collaboratively control and recover fine particles from the flue gas of heavy metal smelting processes,including copper,lead and zinc.Significant improvements have been realized in wet scrubbing technology for removing mercury,fluoride and SO_(2)from flue gas.Gas-liquid sulfidation technology by applying H_(2)S was invented to recycle the acid scrubbing wastewater more efficiently and in an eco-friendly manner.Based on digital technology,a source reduction method was designed for sulfur and fluoride control during the whole aluminum electrolysis process.New desulfurization technologies were developed for catalytic reduction of the sulfur content in petroleum coke at low temperature and catalytic reduction of SO_(2)to elemental sulfur.This work has established the technology for coupling multi-pollutant control and resource recovery from the flue gas from non-ferrous metallurgy,which provides the scientific theoretical basis and application technology for the treatment of air pollutants in the non-ferrous metallurgy industry.