Treatment Of Different Wastewaters Research Articles

Upflow Anaerobic Sludge Blanket (UASB) reactors for Bio-methane production from limed tannery fleshings: Lab and pilot scale reactors

The Upflow Anaerobic Sludge Blanket reactor is a viable high-rate anaerobic digestion design for the treatment of different wastewater with low to high solubility. This can also be used for the treatment of solid wastes with less HRT. In this study, the performance evaluation of a lab-scale UASB reactor was carried out for different hydraulic retention times of 24, 21, 18, 15 and 12 h for obtaining the best HRT for tannery fleshings. The gas production varied between 3.7 – 4.5 L with a methane content of 64.31 – 67.72%. It was observed that the maximum gas production was at 18 h HRT and this optimized condition was applied to the pilot-scale UASB reactor. The performance evaluation of the pilot-scale UASB reactor was carried out with an HRT of 18 h. The gas production of 450 ± 50 L, the maximum specific gas production of 0.274 m3/kg of VS destroyed and 0.239 m3/kg of TS destroyed was obtained and the maximum biogas productivity of 0.495 L was observed at 18 h HRT with the highest methane content of 67.86%. The payback period of the pilot scale reactor is 3.2 years.

A critical review of inverse fluidized bed reactors-start-up optimization strategies and wastewater treatment.

A critical evaluation of strategies used for reducing start-up time and biological wastewater treatment using an inverse fluidized bed reactor (IFBR) was done. The start-up of an IFBR is one of the most important, time-consuming, and limiting steps in wastewater treatment using biofilm reactors. Evaluation of different strategies used by various researchers is helpful in future research works with this reactor. Different types of treated wastewater, the effect of wastewater characteristics, carriers used, and reactor hydrodynamics on the reactor performance were reviewed in detail in the first part. The second part of this review covers the use of an IFBR in the biological treatment of different wastewaters through multiple biochemical pathways and how it helped improve performance compared to other reactors. This will enable the researchers to understand the novelty of an IFBR for wastewater treatment and allow them to use it as a potential reactor.

Insight into the roles of microenvironment and active site on the mechanism regulation in metal-free persulfate activation process coupling with an electric field

The regulation of the persulfate activation mechanism is highly desirable and meaningful for the treatment of different wastewaters. The role of active sites for mechanism regulation in carbon-driven persulfate activation is still ambiguous due to the complex and easily neglected microenvironment (concentration distributions of organics and oxidants) nearby carbon catalyst. This work aims to reveal the critical roles of active site and microenvironment on the activation mechanism through N-doped modification and application of an electric field (AC/PS/EC). Several N-doped activated carbon catalysts were prepared by activating for different times to adjust the surface active center and adsorption selectivity under an electric field. The contribution ratio of radical pathway and non-radical pathway for organic elimination significantly varied with the concentration distribution of organics and oxidants nearby the microelectrodes. The increased electro-adsorption of persulfate anion was found to be the primary promoting factor for the radical pathway for organic oxidation, resulting in a synergistic increase in degradation rate in the AC/PS/EC system. The quantitative structure-activity relationships analysis also revealed that the electro-adsorption selectivity was dominated by the surface graphitic N and pore structure of catalyst. This study sheds new light on the oxidative pathway regulation to deal with complex wastewater in a flexible and efficient manner.

Sistema de tratamiento de aguas residuales domésticas por electrocoagulación utilizando energía solar fotovoltaica

This work deals with the design of a domestic wastewater treatment system for the washing machine, which is mainly based on responsibility to the environment in terms of the correct administration and proper management of the most significant asset that man possesses, water. In Mexican homes, one of the main domestic processes is laundry, where a large amount of water is used to clean clothing. Electrocoagulation is a process that can be used in the treatment of different wastewater due to its versatility and environmental compatibility. In the present investigation, the applicability of electrocoagulation for the treatment of domestic wastewater from the washing machine through the use of photovoltaic solar energy was analyzed. The effects of operational parameters such as current density, treatment time on turbidity, , and conductivity were studied. The objective of this project is to research alternatives to domestic wastewater treatment systems from the washing machine, through the use of photovoltaic panels taking advantage of and reusing the water from the washing machine after each washing process. Reduce the waste of the resources from homes, can contribute positively to the environment, and demonstrate that electrocoagulation is a viable alternative in the challenge of protection, conservation, and recovery of water resources.

Potential of Microalgae in Bioremediation of Wastewater

The increase in global pollution, industrialization and fast economic progress are considered to inflict serious consequences to the quality and availability of water throughout the world. Wastewater is generated from three major sources, i.e. industrial, agricultural, and municipal which contain pollutants, such as: xenobiotics, microplastics, heavy metals and augmented by high amount of carbon, phosphorus, and nitrogen compounds. Wastewater treatment is one of the most pressing issues since it cannot be achieved by any specific technology because of the varying nature and concentrations of pollutants and efficiency of the treatment technologies. The degradation capacity of these conventional treatment technologies is limited, especially regarding heavy metals, nutrients, and xenobiotics, steering the researchers to bioremediation using microalgae (Phycoremediation). Bioremediation can be defined as use of microalgae for removal or biotransformation of pollutants and CO2 from wastewater with concomitant biomass production. However, the usage of wastewaters for the bulk cultivation of microalgae is advantageous for reducing carbon, nutrients cost, minimizing the consumption of freshwater, nitrogen, phosphorus recovery, and removal of other pollutants from wastewater and producing sufficient biomass for value addition for either biofuels or other value-added compounds. Several types of microalgae like Chlorella and Dunaliella have proved their applicability in the treatment of wastewaters. The bottlenecks concerning the microalgal wastewater bioremediation need to be identified and elucidated to proceed in bioremediation using microalgae. This objective of this paper is to provide an insight about the treatment of different wastewaters using microalgae and microalgal potential in the treatment of wastewaters containing heavy metals and emerging contaminants, with the specialized cultivation systems. This review also summarizes the end use applications of microalgal biomass which makes the bioremediation aspect more environmentally sustainable. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Evaluation of the photocatalytic performance of molecularly imprinted S–TiO2 by paper microzones

The paper microzones method (PMZs) is a green chemical method that uses the principle of the three primary colors of red, green and blue (RGB) to detect the water quality of the droplets on white paper. However, this method is rarely used in the performance evaluation of photocatalysts. The paper details the first use of paper microzones utilized in the evaluation of photocatalyst performance. A sol-gel method was used to prepare molecularly imprinted modified TiO2 photocatalysts for the treatment of different wastewaters, and characterized the catalysts using XRD and several other methods. The reliability of PMZs on the evaluation of photocatalytic activity and selectivity was also analyzed. The following results were obtained: EP-TiO2 catalysts (EP, ethyl paraben, the imprinting molecule) with different S doping levels were synthesized using a one-step sol-gel method, and the best S doping ratio was found to be n(Ti):n(S) 3:1. S-EP-TiO2 was found to be 100% anatase and showed excellent photocatalytic performance, while the PMZs method accurately determined changes in RGB levels for the photocatalytic degradation process of pollutants using S-EP-TiO2 as the photocatalyst. A photocatalytic kinetic analysis showed the PMZs method was quite suitable for the evaluation of photocatalyst activity, but the evaluation of selectivity needs improvement. This method is a promising green chemistry way to evaluate photocatalyst performance and the rapid detection of outdoor sewage water quality.

Pyrolysis of Scenedesmus obliquus Biomass Following the Treatment of Different Wastewaters

The potential of Scenedesmus obliquus biomass, after treating several wastewaters (WWs) (urban, dairy and brewery industries, cattle and poultry breeding), was evaluated for the production of bio-char, bio-oil and bio-gas, through a pyrolysis process. The experiments were carried out in a fixed bed reactor at a temperature of 748 K during 15 min. The thermochemical behaviour of each microalga was assessed by thermogravimetry analysis and infrared spectroscopy. The bio-oils obtained were also quantified and characterized. The results reveal that (i) all microalgae show a similar thermal degradation behaviour; (ii) microalga grown in urban WW shows a lower percentage of lipids; in dairy and cattle WWs, it shows a high percentage of both proteins and lipids, and in poultry and brewery WWs, it shows a higher carbohydrates content; (iii) the microalga grown in poultry WW shows the lowest protein content, whereas the urban grown microalga showed the highest protein content; (iv) the bio-oil obtained by pyrolysis process showed yields in the range 30–60% (w/w) and showed a high content of aromatic compounds.

Advanced Oxidation Processes (AOPs) in Wastewater Treatment

Advanced oxidation processes (AOPs) were first proposed in the 1980s for drinking water treatment and later were widely studied for treatment of different wastewaters. During the AOP treatment of wastewater, hydroxyl radicals (OH·) or sulfate radicals (SO4 ·−) are generated in sufficient quantity to remove refractory organic matters, traceable organic contaminants, or certain inorganic pollutants, or to increase wastewater biodegradability as a pre-treatment prior to an ensuing biological treatment. In this paper, we review the fundamental mechanisms of radical generation in different AOPs and select landfill leachate and biologically treated municipal wastewater as model wastewaters to discuss wastewater treatment with different AOPs. Generally, the treatment efficiencies rely heavily upon the selected AOP type, physical and chemical properties of target pollutants, and operating conditions. It would be noted that other mechanisms, besides hydroxyl radical or sulfate radical-based oxidation, may occur during the AOP treatment and contribute to the reduction of target pollutants. Particularly, we summarize recent advances in the AOP treatment of landfill leachate, as well as advanced oxidation of effluent organic matters (EfOM) in biologically treated secondary effluent (BTSE) for water reuse.

Comparative study of electricity production and treatment of different wastewater using microbial fuel cell (MFC)

Microbial fuel cell (MFC) is the advancement of science that aims at utilizing the oxidizing potential of bacteria for wastewater treatment and production of elec- tricity. Salt bridge is the economic alternative to highly priced proton-exchange membrane in the construction of an MFC. By altering the concentration of agarose in the fabrication of salt bridge, the performance of various double-chambered MFCs was observed using hostel sew- age wastewater as the substrate. Agarose concentration ranging from 7 to 12 % was used for the study, and opti- mum concentration was observed to be 10 % as it showed maximum current production of 0.97 mA at a voltage of 0.95 V after 528 h of operation from the time of the initial experimental setup. The maximum power density obtained was 78.25 mW/m 2 and the corresponding current density was 82.37 mA/m 2 . A 75.9 % reduction in chemical oxygen demand was obtained in 10 % agarose concentration salt- bridge MFC. All experiments were performed in triplicate and the results are discussed in this research paper.

Analyzing remediation potential of wastewater through wetland plants: A review

Treatment of different wastewater using macrophytes‐vegetated constructed wetland reveals its potential in terms of significant reduction in BOD, COD, suspended solids, total solids, total nitrogen, heavy metals along with remediation of xenobiotics, pesticides and polyaromatic hydrocarbons. The rhizosphere of macrophytes such as Phragmites, Typha, Juncus, Spartina and Scirpus serves as an active and dynamic zone for the microbial degradation of organic and sequestration of inorganic pollutant resulting in successful treatment of domestic, textile and other effluents. Up to 2049–6648 µg metal per gram dry weight of plant biomass are found to accumulate in plant parts i.e. shoots and roots. Major metal removal mechanisms are bioaccumulation in plant parts, phytoextraction and phytostabilization. Different wastewaters treated through this technology are industrial, domestic, dairy, pesticides, PAHs, and xenobiotics containing effluents. Loading limits of the wetland, removal efficiency, biomass disposal and variation in seasonal growth are some of the limiting factors which can be overcome by stimulating the plant microbe interaction through designer rhizospheres involving pigmentation, biostimulation and genetic alterations of plant and associated microbial community. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 9–27, 2014

Electrotreatment of industrial copper plating rinse effluent using mild steel and aluminum electrodes

AbstractBACKGROUND: Heavy metals from aqueous streams can be removed effectively using electrochemical techniques. Although both mild steel (MS) and aluminum (Al) electrodes have long been considered for the treatment of different waste‐waters, unfortunately the reported optimum treatment time, current density, pH and background electrolyte concentration vary greatly. In this work, an electrochemical technique was used for the removal of Cu from electroplating rinse water collected from a local plating industry using MS and Al as electrode materials.RESULTS: Removal of Cu during electrotreatment is due to the combined effect of hydroxide precipitation and electrodeposition. The discharge limit of Cu (3 mg L−1) was achieved with both the electrodes and electrode arrangements. Both MS and Al electrodes showed similar performance for removing copper, however, a lower increase in pH was observed with the MS electrode under identical experimental conditions. NaCl added to increase the solution conductivity decreases Cu removal and inhibits oxide layer formation during electrotreatment. The effluent contains about 6.8 mg L−1 Zn and its discharge limit (4 mg L−1) was achieved within the first 10 min of treatment.CONCLUSIONS: Results obtained from experiments demonstrate that the stipulated limit of both Cu and Zn can be achieved during treatment of industrial plating effluent using MS and Al as electrode materials, depending on current density and treatment time. Copyright © 2009 Society of Chemical Industry

Pilot Plant Studies on the Anaerobic Treatment of Different Wastewaters from a Fish-Canning Factory

Most of the fish-canning factories are characterized by the variety of products to be processed and therefore by the production of effluents with different characteristics. When sea products are manufactured, generated wastewaters are very saline (10-20 gCl−/l) and have a high content of organic matter (10-50 g COD/l). Based on previous studies of the characteristics of different streams generated at a representative factory, which cans tuna, mussel, octopus, sardine and also produces fish meal, and once lab-scale studies showed the viability of the anaerobic treatment, a pilot plant was built in the factory. It consists of a predigester of 7 m3, a suspended sludge digester of 15 m3 and a clarifier of 3 m3. The main results can be summarized in these points: a) It is possible to obtain efficient anaerobic treatment of wastewaters with a concentration of chloride of 15 g/l. b) These wastewaters do not need the addition of nutrients, c) It is possible to treat individually or jointly all the streams generated in the factory. d) The particular results obtained with tuna- and mussel-canning effluents show that it is possible to reach 75-80% of COD removal when organic loading rates of 4 kg COD/m3.d were applied.

Treatment of Different Wastewaters from Pulp and Paper Industry in Methane Reactors

A wastewater from an integrated paper mill with a COD of 1200 mg/dm3 was anaerobically treated in a multi-stage reactor. The BOD7 removal efficiencies of 60-75 % were achieved at maximal loading rates of 5-6 kg COD/m3d and HRT of 4-6 hours due to the granular sludge. Industrial sulphite evaporator condensates from Ca- and Na-processes were treated in anaerobic filters containing light gravel, plastic foam and power plant slag as filter media. The BOD7 removals of 78 % on average were achieved at loading rates of 1.8-3.3 kg COD/m3d with Ca-process evaporator condensates and 80 % BOD7 removals were achieved with Na-process condensates at loading rates of 3.5-4.1 kg COD/m3d.