Removal of Dyes in Aqueous Media with Hydrochar Base of Solid Tanneries Waste: Optimization Process and Application

The Response Surface Methodology (RSM) was used to optimise the conditions of preparation of activated hydrochar from tannery solid waste by hydrothermal carbonisation (HTC). The main factors such as residence time, moisture content and final carbonisation temperature were investigated during the optimisation of hydrochar preparation conditions. The three responses investigated are hydrochar yield, iodine and methylene blue indices. The results of experimental analyses showed that the yield of hydrochar decreases with increasing final temperature, leading to the formation of micropores inside the carbonaceous solid. The optimum conditions for preparing the following hydrochar were obtained: 83.10%, 390.44 mg∙g−1 and 259.63 mg∙g−1 respectively for the hydrochar yield, the iodine and methylene blue indices. The specific surface area of prepared hydrochar is 849.160 m2/g, SEM micrographs showed a porous heterogeneous surface and particularly, the hydrochar surface also revealed external pores on the hydrochar surface which acted as a pathway to the micropores. Fourier transform infrared (FTIR), however, showed a predominance of acid functions on the surface of the carbonaceous solids. Tests were carried out to eliminate indigo carmine in aqueous media. Activated hydrochar showed a high level of activity, with the Langmuir and Freundlich isotherms giving an adsorption quantity of 354.610 mol/g and a KF constant of 468.2489, respectively. The findings of the research revealed that hydrochar produced is well adapted for dyes removal.

Bacterial diversity in Fez tanneries and Morocco's Binlamdoune River,using 16S RNA gene based fingerprinting

Tannery wastewater causes serious ecological and sanitary damage. Chemical analysis of water from Binlamdoune River of the medina of Fez was conducted and the results revealed the presence of toxic elements from tanneries and other industrial activities, which strongly affected water quality. To determine the effectiveness of bioremediation for depollution, we studied the abundance and diversity of bacteria residing in these polluted environments. Conducting denaturing gradient gel electrophoresis （PCR-DGGE） of the 16S rDNA area using primers related to bacteria showed a bacterial community belonging to eubacterial groups, that is, Epsilonproteobacteria, Clostridia, Lactobacillales, Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria. In addition, cloning displayed the presence of clones belonging to the Firmicutes group. Moreover, scanning electron microscopy revealed a significant heterogeneity of microorganism forms and structures. These endogenous microbes could have a significant role in the purification of Binlamdoune River and Fez tannery wastewater.

关于和式极限的两个定理及其应用

从2017年3月第八届全国大学生数学竞赛决赛(数学类)的一道题入手,介绍了两个相关和式极限的定理,推广了一些结果.这些结论有助于完善相关教学内容.

反常积分号下取极限的两个定理及应用

针对n→∞时相应反常积分的极限介绍两个有用的定理,特别是积分形式的Tannery定理,这在现有的文献中很少见到.这些结果有助于完善教材相关内容.最后给出了几个应用例子.

和式极限的一致等价替换定理

通过引入数列的一致等价概念给出和式极限的一致等价替换原理,并结合Tannery定理,得到一类和式极限的结果.进而,探求一些和式极限的收敛阶.

与定积分有关的极限

对于与定积分有关的数列极限,梳理一些已知结论,得到两个命题.给出多个应用例子,有些例子本身就是有用结论.

Thermal behaviors and heavy metal vaporization of phosphatized tannery sludge in incineration process

The high concentration of heavy metal (Cu, Cr, Zn, Pb) in tannery sludge causes severe heavy metal emissions in the process of incineration. In the present investigation, the tannery sludge was treated with 85% phosphoric acid before the incineration process in the tube furnace to control the heavy metal emissions. The thermal behavior and heavy metal vaporization of pre-treated tannery sludge were investigated, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were also implemente...

Treatment of tannery wastewater by electrocoagulation

Treatment of tannery wastewater by electrocoagulation with low cell current （≤ 1A） and soluble electrodes （mild steel electrodes and aluminum electrodes） was studied. Compared with aluminum electrodes, mild steel electrodes were more effective for the removal of sulfide, with a removal efficiency of over 90%. But during the treatment process, black color precipitate typical to iron（Ⅱ） sulfides was produced. While aluminum electrodes were effective to eliminate the colority of the effluent, the removal efficiency of sulfide was lower than 12%. The mechanisms of the removal of chemical oxygen demand, ammonia, total organic carbon, sulfide and colority with the two soluble electrodes （mild steel and aluminum electrodes） were discussed in detail. In order to exert the predominance of diffenent types of electrodes, the tannery wastewater was treated using mild steel electrodes first followed by the filter and finally by the aluminum electrodes, the elimination rates of chemical oxygen demand, ammonia, total organic carbon, sulfide and colority were 68.0%, 43.1%, 55.1%, 96.7% and 84.3%, respectively, with the initial concentrations 2413.1 mg/L, 223.4 mg/L, 1000.4 mg/L, 112.3 mg/L and 256 dilution times, respectively. The absorbance spectra and energy consumption during electrocoagulation process were also discussed.

Laboratory scale studies on removal of chromium from industrial wastes

Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes, paint pigments, manufacturing units etc. Chromium exists in aqueous systems in both trivalent (Cr 3+) and hexavalent (Cr 6+) forms. The hexavalent form is carcinogenic and toxic to aquatic life, whereas Cr 3+ is however comparatively less toxic. This study was undertaken to investigate the total chromium removal from industrial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation. The study was conducted in four phases. In phase Ⅰ, the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected. As a result, pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively. Phase Ⅱ showed that lower dose of sodium meta bisulfate was sufficient to obtain 100 % efficiency in reducing Cr 6+ to Cr 3+, and it was noted that reaction time had no significance in the whole process. A design curve for reduction process was established which can act as a tool for treatment of industrial effluents. Phase Ⅲ studies indicated the best pH was 8.5 for precipitation of Cr 3+ to chromium hydroxide by using lime. An efficiency of 100 % was achievable and a settling time of 30 minutes produced clear effluent. Finally in Phase Ⅳ actual waste samples from chrome tanning and electroplating industries, when precipitated at pH of 12 gave 100 % efficiency at a settling time of 30 minutes and confirmed that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.

Removing contaminants from tannery wastewater by chemical precipitation using CaO and Ca(OH)2

The removal of Cr,sulfates and Chemical Oxygen Demand(COD)from industrial tannery wastewater by chemical precipitation was carried out using Calcium oxide(CaO)and Calcium hydroxide(Ca(OH)2).Different doses of alkalis,ranging from deficiency to excess hydroxyl species over the stoichiometric necessary,were used to remove theoretically the 100%of Cr[0.3-3.2 g alkali·(g Cr^3+)^-1].The precipitation was carried out at room temperature,10 min of vigorous stirring,200 r·min^-1 and a settling time of 24 h,followed by separation and characterization of liquid product.As result of addition of alkalis,pH underwent increase as did the alkali concentration.The removal of Cr,and sulfates also increased as alkali concentration did,although for first species the changes at higher alkali contents were less evident.COD removal on the other hand,did not follow a unique trend,instead exhibited a maximum.Based on our results,selection of a specific dose of alkali was carried out taking as reference the efficiency on total chromium removal,keeping the pH in the range 7 to 9 to ensure Cr precipitation as chromium hydroxide.With those conditions,jar test was used to produce enough liquid product in order to determine the removal percent of several other species.The removal percent of the species was as follows:Cr,SO4^2-,ZnSO4,FeSO4,CN^-1,NiSO4,Fe2[Fe(CN)6]at 99.8%,66.9%,99.6%,21.4%,70.9%,52.8%and 76.4%with CaO,and 99.8%,61.6%,99.9%,7.1%,84.0%,54.4%and 90.5%with Ca(OH)2,respectively.

Impacts of Chromium from Tannery Effluent and Evaluation of Alternative Treatment Options

The paper has focused on the challenges/impacts of tannery effluent and evaluates the alternative treatment options used to treat, recover or recycle chromium from the waste water. The paper was done entirely on secondary data by consulting literature sources including scientific journals, chapters of books, conference report papers and websites. The results of this review paper indicated that chromium is highly toxic and carcinogenic to human beings, animals, plants and the general environment (soil and water sediment). It is found out that chrome is the primary threat when ever tanning industry comes in to practice. Though many treatment options were evaluated to prevent its consequence on the environment, neither of them could achieve to treat or recover chrome 100%. Treatment options are either;inef-ficient, complicated, energy demanding, costly or applicable to a certain parts of the world due to technology or skilled man power demand. Therefore, to tackle this serious challenge stringent environmental regulation with law enforce-ment has to be exercised to use better treatment system which is widely applicable. Polluters must also know the envi-ronmental cost of their industry and treated according to polluter pay or precautionary principles. Moreover, the gen-eral public has to be aware of it and all concerned organizations and governments has to work hand in hand to reach zero discharge level or at least to attain the EPA chrome discharge

Removal of Cr from tannery sludge by bioleaching method

Bioleaching of Cr（Ⅲ） from tannery sludge using the mixture of ingenuous iron- and sulfur-oxidizing bacteria was investigated in batch flasks. Experiments involved the adaptation of indigenous iron-and sulfur-oxidizing bacteria, the pre-acidification the sludge to pH 6.0 and the addition of energy substrates. Results showed the inoculation of mixture of ingenuous iron- and sulfur-oxidizing bacteria and co-addition of Fe^2 and elemental sulfur accelerated acid production and increase of oxidation-reduction potential originating from the bio-oxidation of Fe2^＋ and elemental sulfur. Dissolved Cr concentration increased concomitant with pH decreased in the sludge and reached its maximum removal of 95.6%. The amelioration of the odor of bioleached sludge could be noted. However, 20.4%o of N, 24.5% of P and 14.3% of organic matter were lost in the bioleaching process. The residual Cr content in the leached tannery sludge was acceptable for use in agriculture. This study had shown the feasibility of applying the bioleaching process, developed for sewage sludge, to tannery sludge with high Cr.

Studies on Feasibility of Reverse Osmosis (Membrane) Technology for Treatment of Tannery Wastewater

Tanneries reusing wastewater by combination of conventional and advanced Reverse Osmosis (RO) treatment technologies were assessed for technical and economic viabilities. Conventional treatment methods such as neutralization, clari-flocculation and biological processes are followed to clean the effluents before feeding to RO membrane modules. The characteristics of untreated composite effluents such as pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), and total chromium were in the range of 4.00-4.60, 680-3600 mg/L, 1698-7546 mg/L, 980-1480 mg/L, 4200-14500 mg/L, and 26.4-190 mg/L, respectively. Inorganic ions like Ca2+, Na+, Cl– and SO42– were found more in the wastewaters. Conventional treatments significantly removed the organic pollutants however failed to remove dissolved inorganic salts. Membrane technology removed the salts as well as remaining organic pollutants and the product water is reused in the process. The studied tanneries (5 numbers) have achieved 93-98%, 92-99% and 91-96% removal of TDS, sodium and chloride, respectively. Seventy to eighty five percentage of wastewater was recovered and recycled in the industrial processes. The rejects are subject to either solar evaporation system or Multiple Effect Evaporation (MEE) technology. The resulting salts are collected in polythene bags and disposed into scientifically managed secured land fill (SLF) site. The cost of wastewater treatment for operation and maintenances of RO including the pre-treatments (conventional methods) is INR 100-110 m-3.

Studies on Chromate Removal by Chromium-Resistant Bacillus sp. Isolated from Tannery Effluent

A chromate-removing strain was isolated from spent chrome effluent and identified as Bacillus circulans strain MN1. The isolated strain was studied for resistance to Cr (VI) and its ability to remove Cr (VI). The strain was found to tolerate Cr (VI) concentration as high as 4500 mg/L, but the cells growth was heavily influenced when initial Cr (VI) concentration was increased between 1110 mg/L and 4500 mg/L while Cr(VI) at 500 mg/L to 1110 mg/L did not suppressed the cells growth. The experiments also demonstrated that the cells removed toxic Cr (VI) more efficiently at 30?C compared with that at 25?C and 35?C. The optimum initial pH for Cr (VI) removal was 5.6 and final pH values of 5.1-5.6 were observed for initial pH 5.2-5.7.

一种新的q概率分布及其应用

引入两个参量a和b,在q移位阶乘和Al-Salam-Carlitz积分的基础上,介绍了一种新的q概率分布.这种q概率分布推广了Wang提出的概率分布.在应用中,可以简化所构造的随机变量数列,通过构造一维随机变量数列,应用勒贝格控制收敛定理和Tannery定理,直接证明q二项式定理和q-Guass公式.

Odour Removal in Leather Tannery

Toxic odour causes pollution to environment. Removal of odour from wet processing sections of leather tanneries is important to preserve safety and occupational health. Such odour causing gases are identified in nature and are identified mostly as ammonia, Hydrogen sulfide and Volatile organic compounds. These gases, evolving from tanning drums, were experimentally quantified and analysed. Techniques for the abatement of odorous gases are designed using chemical methods. Scrubbing towers based on absorption of gases by liquid are designed and fabricated to evaluate the performance of the system in laboratory scale. Those gases were reduced in the concentration by absorbing through the packed bed vapour phase absorption using the activated carbon as the adsorbent. Results are helpful to conclude that the absorption technique presented here to reduce these toxic emission loads, seems to be simpler and economically cheaper.

The influence of old leather tannery district on chromium contamination of soils,water and plants

The paper demonstrates the actual level of chromium contamination at the site of the old tannery waste lagoon in Serniki community (SE Poland). Despite the fact that since 1994 this area is not exploited, the chromium presence is still detected in soil, water and plants. The current study is the 4th phase (after 1989, 2001 and 2004) of checking and controlling the chromium concentration in this territory. The chromium content was assessed after soil and plant mineralization using FAAS method. Total chromium concentrations in soil samples reached values of 2.25 - 18.25 mg·kg-1 dry mass. Levels of chromium in water samples ranged between 0.008 and 0.017 mg·dm-3 for Wieprz River and the trough, situated in the tannery centre, respectively. Absorption of chromium by plants depended from the plant species. The highest Cr content in the stalks of Oenothera biennis, whilst the lowest in Phragmites australis were detected. Finally, it was assumed that soil chromium content noted in 2009 was by 42% - 83% lower in relation to the data from 2004. Consequently, nowadays the tannery waste lagoon site is not so threat to the health of local residents and to the surrounding ecosystem.

Chromium adsorption on surface activated biochar made from tannery liming sludge:A waste-to-wealth approach

In a beamhouse,liming plays a key role in the removal of hair/wool and epidermis,but problems are created when waste liming sludge is discharged to the environment.The treatment of tannery wastewater is another major challenge to the industry.In this study,thermally-activated biochars derived from liming sludge were studied for their effective adsorption of chromium(Cr)from the tannery wastewater.The thermally activated biochars(B500,B550,B600,and B650)were prepared at different temperatures from the liming sludge.Their characteristics before and after the treatment were investigated using Fourier transform infrared spectroscopy,energy dispersive X-ray spectroscopy,Bru-nauer-Emmett-Teller,and scanning electron microscopy analyses.The related functional groups(C-H,O-H,C-N,and=C-O)and chromium adsorption capacity were determined according to the surface morphology,element contents(C,O,Ca,Na,Al,Mg,and Si),surface area(5.8-9.2 m^(2)/g),pore size(5.22-5.53 nm),and particle size(652-1034 nm)of the experimental biochars.The biochar originated at 600°C from the tannery liming sludge(B600)had a greater surface area with a chromium adsorption capacity of 99.8%in comparison to B500,B550,and B650 biochars.This study developed an innovative way of utilizing liming sludge waste to minimize the pollution load and wastewater treatment cost in the tannery industry.

Environmental aspects and health risks of leather tanning industry:a study in the Hazaribag area

The tannery industry in Hazaribag,which is one of the most polluted areas in Dhaka City,produces a huge quantity of wastes every day.Without treatment,these are discharged into the Buriganga River and pollute the surrounding environment.This article examines the impacts of tannery wastes on workers'health and the environment in that particular area.As part of the methodology,a semi-structured interview was conducted in order to obtain quantitative data and 112 respondents were interviewed using purposive sampling.The findings of the study indicate that tannery wastes affect the environment severely,causing ecological imbalance and the spreading of different kinds of fatal and contagious disease among the tannery workers and other individuals.Moreover,the current waste management system of the Hazaribag tannery industries is very suspect due to outdated technology,defective drainage systems,lack of financial input,and the exploitative attitude of their owners.The findings also indicate that tannery workers are unaware of the effects of tannery waste as they choose not to wear personal protective equipment in the workplace.This empirical study helps policy makers implement appropriate measures to raise awareness,among both owners and workers,that can influence changes in the public's attitude and reduce environmental pollution to a great extent.Although considerable research has been undertaken focusing on tannery waste impact assessment,less attention has been paid to the issue of workers'health.Therefore,both governments and policy makers can benefit from the findings of this study.

Studies on solar flat plate collector evaporation systems for tannery effluent(soak liquor)

Heat and mass transfer analysis of an incompressible, laminar boundary layer over solar flat plate collector evapora- tion systems for tannery effluent (soak liquor) is investigated. The governing equations are solved for various liquid to air velocity ratios. Profiles of velocity, temperature and concentration as well as their gradients are presented. The heat transfer and mass transfer coefficients thus obtained are used to evaluate mass of water evaporated for an inclined fibre-reinforced plastic (FRP) solar flat plate collector (FPC) with and without cover. Comparison of these results with the experimental performance shows encouraging trend of good agreement between them.