Biodegradable Flocculants Research Articles

Treatment of Textile Wastewater using Biodegradable Flocculants of Chitosan and Extracted Pandan Leaves

The study investigated the performance of chitosan and extracted pandan leaves towards treatment of textile wastewater by using flocculation process. Pandan leaves were extracted by using solvent extraction method. Flocculation process was conducted using a Jar test experiment. The effect of dosage, pH, and settling time on reduction of COD, turbidity and color of textile wastewater was studied. The results obtained found that chitosan was very effective for reduction of COD, turbidity, color and indicator for color. The best condition for COD and turbidity removal was achieved at 0.2 g dosage, pH 4 and 60 minutes of settling time. Under this condition, about 58 and 99% of COD and turbidity was removed, respectively. However, the results obtained using extracted pandan was opposite compared to the chitosan. Extracted pandan was not able to remove both COD and turbidity of the waste.

Polymer-Grafted Cellulose Nanocrystals as pH-Responsive Reversible Flocculants

Cellulose nanocrystals (CNCs) are a sustainable nanomaterial with applications spanning composites, coatings, gels, and foams. Surface modification routes to optimize CNC interfacial compatibility and functionality are required to exploit the full potential of this material in the design of new products. In this work, CNCs have been rendered pH-responsive by surface-initiated graft polymerization of 4-vinylpyridine with the initiator ceric(IV) ammonium nitrate. The polymerization is a one-pot, water-based synthesis carried out under sonication, which ensures even dispersion of the cellulose nanocrystals during the reaction. The resultant suspensions of poly(4-vinylpyridine)-grafted cellulose nanocrystals (P4VP-g-CNCs) show reversible flocculation and sedimentation with changes in pH; the loss of colloidal stability is visible by eye even at concentrations as low as 0.004 wt %. The presence of grafted polymer and the ability to tune the hydrophilic/hydrophobic properties of P4VP-g-CNCs were characterized by Fourier transform infrared spectroscopy, elemental analysis, electrophoretic mobility, mass spectrometry, transmittance spectroscopy, contact-angle measurements, thermal analysis, and various microscopies. Atomic force microscopy showed no observable changes in the CNC dimensions or degree of aggregation after polymer grafting, and a liquid crystalline nematic phase of the modified CNCs was detected by polarized light microscopy. Controlled stability and wettability of P4VP-g-CNCs is advantageous both in composite design, where cellulose nanocrystals generally have limited dispersibility in nonpolar matrices, and as biodegradable flocculants. The responsive nature of these novel nanoparticles may offer new applications for CNCs in biomedical devices, as clarifying agents, and in industrial separation processes.

Flocculation characteristics and biodegradation studies of Gum ghatti based hydrogels

Biodegradable flocculants of Gum ghatti (Gg) with acrylamide (AAm) were prepared through graft co-polymerization technique using potassium persulphate (KPS)–ascorbic acid (ABC) redox pair as initiator and N,N′-methylene-bis-acrylamide (MBA) as a crosslinker. Gg-cl-poly(AAm) was found to exhibit pH and temperature responsive swelling behavior. Maximum flocculation efficiency of Gg-cl-poly(AAm) was observed with 15mgL−1 polymer dose in acidic medium at 50°C. Biodegradation studies of Gg and Gg-cl-poly(AAm) were done using composting method. Gg was found to degrade within 20 days, whereas, Gg-cl-poly(AAm) was found to degrade 88.18% within 60 days. Different stages of bio-degradation were characterized through FT-IR and SEM techniques.

Evaluation of Non-Conventional Coagulants to Remove Turbidity from Water

Coagulation and flocculation are basic chemical engineering operations employed to remove suspended solids from water. The growing concern for environmental and ecological issues warrants the use of the biodegradable flocculants in wastewater and industrial effluent treatment. In this work, unconventional coagulant, namely lactic acid, calcium lactate, sodium lactate, and citric acid were studied in comparison with AlCl3, a usual coagulant widely employed to remove water turbidity. It was observed that lactic acid and calcium lactate were able to reduce the water turbidity similarly to AlCl3. This fact can be very interesting because lactic acid salts can be produced by biotechnological process, and contrarily to aluminium salts, they are biodegradable, reducing the risk for human and animal’s health.

Organic flocculants for the removal of phytoplankton biomass

The formation of noxious phytoplankton blooms causes deterioration of water quality in aquaculture ponds and reservoirs, but also in swimming pools and aquaria. We have studied the effects of selected cationic polyacrylamides on natural phytoplankton community, which was investigated by a decrease of chlorophyll a content in the water column and photosynthetic activity of phytoplankton floccules. Results indicate that cationic polyacrylamides are able to remove more than 80% of phytoplankton biomass. Moreover, no cell damage or lysis was observed by microscopic observation after flocculation. To our knowledge, this is the first report suggesting the removal of cyanobacterial blooms by organic flocculants. Cationic polyacrylamides are biodegradable organic flocculants with low toxicity to aquatic organisms, and seem to be a prospective tool with a possibility for algal or cyanobacterial bloom management in aquaculture.

Enhancement of oil droplet removal from o/w emulsion by adding methylated milk casein in flotation technique

AbstractTo clarify oil‐in‐water (o/w) emulsion, flotation experiments were conducted by adding methylated milk casein (MeCS), which is a biodegradable flocculant. Emulsion used in this study was prepared by ultrasonic emulsification of heavy oil (bunker‐A) and sodium dodecyl sulfate (SDS) solution. It was found that addition of MeCS enhanced clarification of oil droplets from o/w emulsion solution due to floc formation by adding MeCS. An optimum dosage of MeCS to form effective floc was determined by the relative turbidity in a clarification experiment. In flotation experiments, clarification ability was evaluated by removal rate constant, k, obtained by fitting of turbidity data to a pseudo‐first‐order kinetic equation. In case of varying dosage of MeCS and keeping superficial gas velocity, Ug, at constant value (5.48 × 10−2 cm/s), removal rate was greatly influenced by amount of MeCS dosage. The maximum value of k was also obtained at the most optimum dosage of MeCS, and k decreased with adding lesser or larger amount of MeCS than the optimum dosage. On the other hand, in case of keeping the dosage of MeCS at the optimum dosage, and varying superficial gas velocity, up to Ug < ca. 0.2 cm/s, k was increased with increasing superficial gas velocity, and increase in removal rate of oil droplets was mostly proportional with increase in bubble surface area production rate. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

Thermal Degradation of Starch in Production of Environmentally Benign Flocculants. 2. Experiments and Process Identification

Experiments were carried out to produce biodegradable flocculants by phophorylation and heat treatment of corn starch at elevated temperatures in the dry state. The temporal change of molecular weight distribution was measured by HPSEC/MALLS/RI. To elucidate the mechanism and kinetics of degradation during this treatment a Markov-chain stochastic model was used. For this, five molecular weight intervals were defined between >32 10 6 and 2 10 6 Da with exponentially decreasing spans. The probabilities of mass fraction transitions among these intervals at different processing temperatures were determined by fitting the calculated molecular weight distributions to the experimental data. Examining the transition probabilities between various MW intervals, it was concluded that degradation took place gradually by multiple splits of molecules, resulting in stepwise transition of fragments from higher intervals to lower ones. From the values of the transition probabilities between different molecular weight intervals, and considering the evolution of molecular weight distributions during the process, it was concluded that an end-scission mechanism did not play a role in the studied system under the applied conditions. The degradation probability of starch molecules diminished with decreasing molecular weight and increased with the temperature of treatment. These dependences were described by an exponential relationship.

Thermal Degradation of Starch in Production of Environmentally Benign Flocculants. 1. Stochastic Modeling of Degradation Process

The paper deals with the thermal degradation of starch during phosphorylation carried out at elevated temperatures in the solid phase to produce biodegradable flocculants. The aim of the work reported here was to elucidate the mechanism and kinetics of the degradation process. In the first part of this study, a discrete Markov-chain model was proposed and discussed. The whole molecular weight range of the raw material and degradation products was divided into 10 discrete intervals. Mass transitions between them were considered as the consequence of splits of molecules to fragments, occurring with given probabilities at different positions within the molecules during a time step. Supposing various distributions of split probabilities along the length of starch molecules, and considering different influences of molecular weights on these probabilities, simulations were carried out resulting in characteristic patterns in the evolution of molecular weigh distributions during the process. These characteristics made it possible to identify the mechanism of degradation.

A Study on the Rate and Mechanism of Thermal Degradation of Starch in Production of Flocculants

Experiments and theoretical study were carried out to investigate the degradation rate and mechanism of starch molecules to establish suitable conditions of producing biodegradable flocculants by phosphorylation at elevated temperatures. The whole molecular weight range of original starch and the possible starch derivatives was divided into five intervals using an exponential scale. A Markov-chain stochastic model with transition probabilities from the higher molecular weight categories to the lower ones was proposed to analyze and explain the experimental findings. By fitting the model to the experimental data the transition probability values were determined for the studied process conditions. From these conclusions were drawn for the kinetics and possible degradation mechanism. It was concluded that the degradation of the molecules took place by splitting the molecules to several pieces, but no end-chain-scission mechanism was present under the studied conditions.

Removal of Dyes by Biodegradable Flocculants: A Lab Scale Investigation

In the present communication, experiments were conducted to investigate the efficiency of mucilage isolated from fruits of Coccinia indica for the treatment of simulated textile wastewater samples containing direct dyes, direct fast scarlet (DFS) and direct fast yellow (DFY) and vat dyes, golden yellow (GY) and nyanthrene yellow (NY). This mucilage (Ku) is an ecofriendly and low cost anionic polysaccharide capable of reducing color from textile effluent through flocculation process. The flocculation efficiency of Ku was improved by grafting polyacrylamide onto it. The copolymer thus obtained (Ku‐g‐PAM) showed much better flocculation capacity than that of its precursor by reducing the flocculant dose and treatment time to half. The results showed that the maximum removal was obtained at acidic pH with both the flocculants. Statistical analysis showed that the change in percent removal with pH was highly significant in case of direct dyes while it was significant in case of vat dyes removal. The plausible mucilage‐dye interaction and flocculation mechanism has been discussed.

Flocculation of diatomite by methylated milk casein in seawater

A new biodegradable flocculant was prepared from a common and inexpensive protein. Milk casein was methylated in a 0.05 M HCl methyl alcohol solution at room temperature. The methylated milk casein (MeCS), having a methylation degree of 81%, was applied to the separation or flocculation of diatomite in seawater (pH 8.1±0.1) at room temperature (18–23 °C). The flocculating ability of MeCS was evaluated by a sedimentation balance method (cumulative measurement method). The diatomite suspension was effectively flocculated by the addition of a small amount of MeCS (0.25 wt% of the diatomite weight). The results of sedimentation analysis showed that the size–frequency curve had a very sharp and high peak; thus the diatomite floc formed by MeCS had a rather uniform size. The settling velocity of diatomite floc at the appropriate MeCS dosages (0.25–2 wt% of diatomite) was about 3×10 −3 m s −1.

Biodegradable drag reducing agents and flocculants based on polysaccharides: Materials and applications

AbstractOrganic and inorganic flocculants are used in treatment of water and industrial effluents. Polymeric flocculants, synthetic as well as natural, because of their natural inertness to PH changes, low dosage, and easy handling, have become very popular in industrial effluent treatment. It has been established in the authors' laboratory that by grafting polyacrylamide branches on rigid backbone of polysaccharides, the dangling grafted chains have easy approachability to contaminants in effluents. Thus grafted polysaccharides are very efficient, shear stable and biodegradable flocculants. They also exhibit turbulent drag reducing characteristics. Among grafted guar gum, xanthan gum, carboxymethyl cellulose, and starch, grafted starch performs the best. Starch consists of amylose (a low molecular weight linear polymer) and amylopectin (a high molecular weight, branched polymer). The grafted amylopectin is found to be the best flocculant for various kinds of industrial effluents, providing credibility to the above‐cited model. In the present paper, the details about grafted polysaccharides as turbulent drag reducers and flocculants are given, along with their applications.

Research Watch: Biodegradable flocculant

ADVERTISEMENT RETURN TO ISSUEPREVDepartmentsNEXTResearch Watch: Biodegradable flocculant Wastewater Cite this: Environ. Sci. Technol. 1997, 31, 7, 303APublication Date (Web):June 8, 2011Publication History Published online8 June 2011Published inissue 1 July 1997https://doi.org/10.1021/es972343bRIGHTS & PERMISSIONSArticle Views102Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts Get e-Alerts

微生物が生産する新しいバイオ凝集剤

Rhodococcus erythropolis produces a kind of microbial flocculant. This bioflocculant was able to efficiently flocculate all the suspended solids tested in an aqueous solution. Among those tested were microorganisms such as E. coli and baker's yeast, activated sludge, algae, kaolin clay, muddy water, river bottom sediment, ash and charcoal powder. The bioflocculant NOC-1 from Rhodococcus erythropolis has a wide flocculating activity against both organic and inorganic materials.From an aqueous solution of a water soluble pigment, removal of the water soluble pigment was attained by the bioflocculant NOC-1. The bioflocculant NOC-1 was able to efficiently flocculate and precipitate the soluble pigment in an aqueous solution tested. Among those efficiently tested were black ink, melanoidin pigment (blackish brown pigment) and black colored pigment of the black liquor of pulping industry.This bioflocculant was purified, and was found to be composed mainly of protein. This bioflocculant is biodegradable flocculant which causes no problem of environmental pollution.