Effects of Coagulation and Ozonation Pretreatments on Biochemical Treatment of Fluid Catalytic Cracking Wastewater

Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and denitrification reactions, was used to assess their possible biodegradation. Because of the negative effects of high salt concentration (3%), heavy metals and toxic organic matter on microorganisms’ activities, some techniques consisting of dilution, coagulation and flocculation, and ozonation pretreatments, were gradually tested to evaluate chemical oxygen demand (COD), ammonia-nitrogen (ammonia-N) and total nitrogen (TN) removal rates. In this process of FCC wastewater, starting with university-domesticated sludge, the ammonia-N and TN removal rates were worst. However, when using domesticated SBR’s sludge and operating with five-fold daily diluted influent (thus reducing salt concentration), the ammonia-N removal reached about 57% while the TN removal rate was less than 37% meaning an amelioration of the nitrification process. However, by reducing the dilution factors, these results were inflected after some days of operation, with ammonia-N removal decreasing and TN barely removed meaning a poor nitrification. Even by reducing heavy metals concentration with coagulation/flocculation process, the results never changed. Thereafter, by using ozonation pre-treatment to degrade the detected organic matter of di-tert-butylphenol and certain isoparaffins, COD, ammonia-N and TN removal rates reached 92%, 62% and 61%, respectively. These results showed that the activities of the microorganisms were increased, thus indicating a net denitrification and nitrification reactions improvement.

Treatment of pharmaceutical wastewater containing recalcitrant compounds in a Fenton-coagulation process

The advanced treatment using integrated Fenton＇s reaction and coagulation process was investigated in this study. Before the advancement, the pharmaceutical wastewater containing lincomycin hydrochloride was pretreated by UASB （upflow anaerobic sludge bed） and a SBR （sequencing batch reactor） process. The residual recalcitrant compounds, measured by gas chromatographymass spectrometry （GC-MS）, mainly consisted of alcohols, phenols, and nitrogenous and sulfur compounds. The experimental results indicated that when the Fenton＇s reaction was conducted at pH=3.0, H2O2CODOcr=0.27, H2O2/Fe^2＋=3：1 and 30 min of reaction time, and the coagulation process operated at a sulfate aluminum concentration of 800 mg/L and pH value of 5.0, the color and COD in the wastewater decreased by 94% and 73%, respectively; with a finale COD concentration of 267 mg/L and color level of 40 units, meeting the secondary standard of GB8978-1996 for industrial wastewater.

Coal Gasification Wastewater Pretreatment with Coagulation and N_2 Flotation Combined System

A N 2 flotation tank combined with coagulation was developed as a pretreatment equipment of biological process to remove oil and other pollutants in coal gasification wastewater( CGW). With optimal PAC dosage of 20 mg / L,the sole coagulation process achieves removal efficiencies of 29. 34% and 26. 83% for oil and COD,respectively. For the sole N 2 floatation process,the optimal N 2 flux and HRT are 20 m3/ h and 20 min. Meanwhile,the oil and COD removal efficiencies are 35. 41% and 14. 26%,respectively. For the combined system of coagulation and N 2 floatation,the optimal parameter values are the same as the ones of separate processes. Correspondingly,the removal efficiencies are 46. 28% and 31. 89% for oil and COD, respectively. Besides,BOD 5 / COD of the effluent is improved. In contrast with conventional dissolved air floatation,the inert gas- N 2 prevents the formation of cyclopentenone, pyridine derivatives, and other heterocyclic aromatic hydrocarbons,thus improving the biodegradability of influent for the subsequent biological processes.

Synergistic coagulation of bauxite residue-based polyaluminum ferric chloride for dyeing wastewater treatment

Considering that Fe,Al elements in bauxite residue are active components for water purification,an effective polyaluminum ferric chloride(PAFC)coagulant derived from bauxite residue,with Fe2O3 content>5.1%,Al2O3%>6.5%,basicity>65%,was successfully prepared.The effect of as-prepared PAFC on the zeta potential for printing and dyeing wastewater was investigated.Comparing with polyferric chloride(PFC)and polyferric sulfate(PFS)for printing and dyeing wastewater treatment,prepared bauxite residue-based PAFC exhibited the optimal performance in the aspects of chromaticity and chemical oxygen demand(COD)removal rate.Furthermore,the combination of bauxite residue-based PAFC and PFS for synergy coagulation of such wastewater demonstrated an obvious positive effect.With the proportion between as-prepared PAFC and PFS to be 2.5:1,the COD of treated wastewater could be further reduced to meet the national level A standard of China,providing a promising route to solve the problem of substandard printing and dyeing sewage outfall by a simple coagulation strategy.

Treatment of Intestinal Lavage Wastewater by Coagulation-ASBR-SBR Process

[ Objective] The study aimed to discuss the optimal conditions for the treatment of intestinal lavage wastewater by coagulation-ASBR- SBR process. [ Method] According to the water-quality characteristics of wastewater from a heparin sodium production factory of Jiangsu Province, intestinal lavage wastewater was segregated from enzymolysis wastewater and treated using coagulation-ASBR-SBR process, and the effects of PFS dosage, HRT of ASBR and SBR reactor on the removal rate of COD and NH4＊ -N were analyzed. [ Result] The best dosage of PFS was 0.15 g/L, and the optimal HRT of ASBR reactor was 36 h, while the best HRT of SBR reactor was 15 h. Under the optimal conditions above, the removal rate of COD and NH,＊ -N reached 99.1% and 97.3% respectively, and the quality of the effluent water could reach the first standard of Comprehensive Discharge Standard of Sewage （GB8978-1996）. [ Conclusion ] The research could provide a new process for the treatment of intestinal lavage westewater.

Treatment of phosphate-containing oily wastewater by coagulation and microfiltration

The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitigate the membrane fouling, coagulation for ceramic membrane microfiltration of oily wastewater was performed. The results of filtration tests show that the membrane fouling decreased and the permeate flux and quality increased with coagulation as pretreatment. At the coagulant Ca （OH）2 dosage of 900 mg/L, the removal efficiency of phosphate was increased from 46.4% without coagulation to 99.6%; the removal of COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was about 70% greater than that when Ca（OH）2 was not used. The permeate obtained from coagulation and microfiltration can be reused as make-up water, and the recommended operation conditions for pilot and industrial application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5 m/s. The comparison results show that 0.2 μm ZrO2 microfilter with coagulation could be used to perform the filtration rather than conventional ultrafilter, with very substantial gain in flux and removal efficiency of phosphate.

Enhancement of Quality of Secondary Industrial Wastewater Effluent by Coagulation Process: A Case Study

The local wastewater treatment facility in Yanbu Industrial City receives 24,000 m3/day of industrial wastewater. This wastewater, mostly from refineries and petrochemical industries, goes through physical, biological and chemical stages of treatment. However, the treated water still fails to pass some of the permissible levels set by governmental agencies. This research paper investigated the enhancement of the treatment processes to reduce the turbidity of the effluent treated water. Ferric chloride, ferrous sulfate, alum and commercial synthetic cationic polymer were tried as coagulants. Different conditions (i.e., pH, temperature, dose, stirring rate) were searched. Ferrous sulfate and polymer reduced the final turbidity to acceptable values with very low doses compared with other coagulant.

Assessment of Endotoxin Removal from Reclaimed Wastewater Using Coagulation-Flocculation

Following biological treatment, wastewater continues to have endotoxic active materials. However, because there is a trend of potable reuse and because endotoxic active materials potentially have harmful effects on human health, their removal from water is crucial. Lipopolysaccharide endotoxin has hydrophobic groups, and their removal using a coagulation-flocculation alternative is believed to be efficient. Thus, their removal from reclaimed wastewater using the coagulation-flocculation process was assessed. Secondary effluent samples from a wastewater treatment plant located in Sapporo, Japan, were investigated. It was found that this process gave satisfactory results in removing endotoxins, with an optimum removal rate of up to 40.5%. The endotoxin removal was maximized by adjusting the pH at the low range 4 - 5.5, with an aluminum sulfate dose of 80 mg/L. Further increases of the coagulant dose did not improve the removal efficiency. DOC and turbidity removal were at their optimum at higher pH range 5.5 - 6.5. Thus coagulation and flocculation could be considered as the first barrier and should be followed by other treatments to safely reuse reclaimed wastewater.

Treatment of Wastewater from Dairy Farm by Coagulation Sedimentation

In order to evaluate the processing efficiency of coagulation sedimentation on wastewater from dairy farm and to provide reference for wastewater treat- ment, an experimental study was carried out to investigate effects of coagulant dosage, types, pH, dosage of coagulant aids PAM on removal rate of COD, turbidity and SS in wastewater from dairy farm. The results showed that PAC displayed higher effectiveness in treatment; the removal rates of COD, turbidity and SS were 61.4%, 86.6% and 94.5% respectively when pH was 11.0, PAC dosage was 150 mg/L, and PAM dosage was 4 mg/L. The results indicated that coagulation sedimentation could reduce organic content of wastewater effectively and alleviate the load of subsequent biochemical treatment.

Feasibility Study on the Treatment of Wastewater Containing High-concentration Hg by Coagulation Sedimentation-Adsorption

For the wastewater containing high-concentration Hg,the feasibility of high-concentration Hg in wastewater treated by coagulation sedimentation,adsorption and the combined process was studied. Research results showed that if using the single coagulation sedimentation process,when FeSO_4·7H_2O dosage was 1. 39 g / L,and NaOH dosage was 0. 40 g / L,it could meet discharge requirement,but the reagent cost was 13. 1yuan / t,which was high. Because that there was subsequent adsorption process,it was selected 0. 28 g / L of FeSO_4·7H_2O and 0. 36 g / L of NaOH,and the estimated reagent cost was 2. 62 yuan / t. In selection process of adsorption materials,powdered activated carbon,granular activated carbon and diatomite all could effectively adsorb Hg,and the technology was feasible. When using the combined process of coagulation sedimentation + adsorption to treat the wastewater containing high-concentration Hg( 800 μg / L),removal rate could reach 99%,and operation cost was 2. 71 yuan. It could meet the requirement of sewage discharged into sewer( 20 μg / L) at the technology,and was acceptable at the economy.Therefore,treatment of wastewater containing high-concentration Hg by the combined process was feasible at the aspects of technology and economy.

Recycling of Mud Derived from Backwash Wastewater Coagulation as Magnetic Sodalite Sphere for Zn^(2+) Adsorption

Herein,we reported a method to prepare magnetic sodalite sphere by using the mud from backwash wastewater after polyaluminum chloride(PAC)coagulation.The results showed that approximately 100%of Fe in the wastewater was precipitated as flocculent iron mud(FM)by adding PAC.FM was converted to spherical magnetic sodalite(FMP)with a diameter of 3μm via a facile alkali hydrothermal method without adding Al/Si resources or reductant.The product FMP had the saturated magnetization of 10.9 emu g^(-1) and high Zn^(2+)adsorption capacity of 50.6 mg g^(-1).Without coagulation with PAC,the removal rate of Fe from the wastewater was only 92.7%,and the precipitated mud(RM)was converted to irregular particles(RMP),which had weak magnetic response and low capacity of Zn^(2+)adsorption comparing with FMP.With the method,the Fe in backwash wastewater was effectively recycled,and the generated sludge was converted to well-formed sodalite sphere without generating any secondary waste.

Laboratory Experiments for Arsenic and Ammonium Removal The Combination of Breakpoint Chlorination and Iron（Ⅲ）-Coagulation

Currently, 15% of the total Hungarian population is affected by either the elevated arsenic or ammonium concentration of drinking water, and 8% is affected by both compounds. The break-point chlorination is a well-known method for ammonium removal, however, during the ammonium-removal process carcinogenic and mutagenic by-products （e.g., THM （trihalogenmethane） and AOX （absorbable organically bound halogens）） may be formed. In order to remove these harmful organic by-products, activated carbon adsorption has to be applied in the technology. The break-point chlorine dose is capable of oxidizing the As3＋ to As5＋. The oxidized form of arsenic can be easily converted to solid phase by adding coagulant （Fe（Ⅲ） or AI（Ⅲ） salt） to the water, and the formed iron/aluminium flocs can be removed by simple rapid sand filtration. Laboratory experiments were performed with raw water from two Hungarian settlements, where the water originated from a deep confined aquifer. In the studied settlements, six wells were in operation, and the supplied drinking water contained ammonium above the maximum allowable concentration, and the arsenic content was around the 10 μg/L standard value. It was found that higher chlorine dose （- 10 Cl2：NH4-N） was needed to achieve the breakpoint than the theoretical value （7.6）. The amount of by-products was also measured during the experiments. The AOX concentrations were significantly higher （21.6 μg/L to 143μg/L） in all cases than the THM concentrations （9-18 μg/L）. The needed coagulant doses were also studied in order to achieve the required arsenic concentrations. Fe（Ⅲ） coagulant was applied in all cases, and it was found that 1-1.5 mg/L Fe（Ⅲ） dose was sufficient to achieve 2-5 μg/L arsenic concentration in the treated water. Based on the results, it can be stated that the breakpoint chlorination combined with Fe（Ⅲ） coagulation is a potential technology to achieve the required ammonium and arsenic concentration at the studied settlements. However, activated carbon has to be installed in order to remove the harmful AOX compounds.

Pretreatment of Wastewater Streams from Petroleum/Petrochemical Industries Using Coagulation

Coagulation-flocculation processes using different types of conventional coagulants, namely, ferric chloride (FeCl3), aluminum sulfate (AL2(SO4)3·18H2O), lime and ferrous sulfate (FeSO4) were investigated using the Jar-test technique. A further aim is to determine the optimum conditions for the treatment of industrial wastewater effluents i.e. coagulant dosage, mixing rate, temperature and pH control. Under optimal condition of process parameters, coagulation/flocculation process was able to lower the turbidity well below the permissible level (1.8 NTU). The results indicate that ferric chloride had superior efficiency compared with other coagulants with efficient dose of 800 mg/l. The optimal initial pH of the effluents that enhanced the turbidity removal was 8.6. The temperature showed no significant effect on the turbidity removal.

Bentonite Adsorption &Coagulation Treatment of Recycled Fiber Pulping Wastewater

A bentonite & PAM particle flocculation system was employed in recycled fiber pulp wastewater treatment in this paper. The optimum conditions of the adsorption & coagulation treatment was explored and optimized and effects of the treatment were focused on, especially stickies substances removal. Under the optimal conditions, the removal of MTBE extract and cationic demand reached 91.26% and 86.93%, and the average particle size in the treated wastewater pollutants is reduced from 40.95μm to 0.5μm. In this treatment the removal of CODcr, turbidity, SS and color were 89.67%, 99.56%, 95.58% and 93.08%, respectively. The results showed that the particle flocculation system was effective for the treatment of recycled fiber pulp wastewater, especially for controlling the stickies.

Use of Prosopis laevigata Seed Gum and Opuntia ficus-indica Mucilage for the Treatment of Municipal Wastewaters by Coagulation-Flocculation

Prosopis laevigata and Opuntia ficus-indica grow in arid and semiarid regions of Mexico and other countries. Both produce biopolymers with interesting characteristics from the rheological point of view as well as because of their coagulating-flocculating capabilities. Prosopis produce galactomannans inside the endosperm, very similar to those found in guar, locust bean, and tara gums. Opuntia sp. produces mucilage that contains polygalacturonic acid and five neutral sugars. Prosopis seed gum has not been proposed to be used as coagulant-flocculant before. In the case of Opuntia mucilage, some authors have suggested its use in the treatment of waters, using either the mucilage or the whole cladode powder. The use of these products in the treatment of municipal or even industrial wastewaters could give rise to diverse benefits. From the environmental point of view, treated waters with neither Fe nor Al, nor synthetic polymers would be obtained (with less toxicity risk). Besides, the produced sludges would be smaller in amount, with better biodegradability, and lower metals content. From the economical point of view, the use of these biopolymers would give an added value to the Opuntia and Prosopis culture in Mexico, helping small communities to enhance their incomes by producing environmental-friendly products. This work shows that both Prosopis galactomannan and Opuntia mucilage can be used to treat municipal wastewaters with an initial organic charge of about 827 mg/L as COD by the coagulation-flocculation process, with COD removals for the mesquite seed gum of up to 90% (pH 10, dose of 75 mg/L) and of 60% (pH 7, doses of 50 and 150 mg/L). In the case of mucilage, 65% of the initial COD was removed at pH 10 (dose of 50 mg/L). These figures are very promising for the treatment of wastewaters, with environmental-friendly products.

Sludge Density Prediction in a Wastewater Chemical Coagulation Process

This paper reports an approach to estimate the sludge density in a physicochemical treatment of municipal wastewater, experiments considered 4 coagulants (aluminum sulfate SAl, iron sulfate SFe, aluminum polychloride PAX, iron polychloride PIX), and 2 flocculant products (cationic CP and anionic AP polymers). Experimental approach is based on running a set of jar tests at different coagulant concentrations. After the stirring and resting times took place, pH and conductivity were registered finding that SAl and SFe either with or without polymers are the coagulants producing the higher pH drop. Conductivity measures also establish two kind of data since higher conductivity (about 2000 ) was observed for SAl, and PIX, PIX + CP, PIX + AP;otherwise a conductivity about 1300 was observed for SAl + PC, SFe and PAX alone and with CP or AP. Settleable solids (SST) determined with an Imhoff cone were similar for sulfates and polychlorides, but dry sludge (DS) clearly set up two groups the one with higher sludge content corresponds to sulfates group. The quotient of DS divided by the SST provided an estimation of the apparent sludge density, in this way it was observed that higher densities were obtained for sludge from sulfates at lower coagulant concentrations;also sludge from SFe was heavier than the one from SAl. Otherwise, polychlorides produced a lighter sludge in respect to the one obtained with sulfates, and between them the PIX coagulant provided a heavier sludge than the PAX coagulant.

Use of Natural Coagulants in Removing Organic Matter, Turbidity and Fecal Bacteria from Hospital Wastewater by Coagulation-Flocculation Process

Hospital wastewater represents an infectious and toxic risk to human health and the environment due to its contents. Most hospitals in developing countries, including Benin, do not have a wastewater treatment plant. In this study, the wastewater from two hospitals in northern Benin was characterized and then treated with Azadirachta indica leaves, Moringa oleifera and Luffa cylindrica seeds by coagulation/flocculation process. The wastewater characteristics showed that the collected samples are greatly polluted by organic matter and fecal bacteria such as Escherichia coli, Enterococcus fecal and Total coliforms. Jar-test results revealed that 95.74%, 78%, 49.19% of turbidity, 51.35%, 38.32%, 22.19% of COD, 93.16%, 85.26%, 83.30% against Escherichia coli, 92.11%, 90.93%, 94.60% against total Coliforms and 99.37%, 91%, 99%, 55.07% against Enterococcus were removed from hospital wastewater using Moringa oleifera, Luffa cylindrica seed and Azadirachta indica leaves respectively at dose of 100 mg/L. The results highlighted that the natural coagulants could be successfully used for the removal of turbidity and fecal bacteria from hospital wastewater.

Research on Treating Thallium by Enhanced Coagulation Oxidation Process

[Objective] The aim was to treat acidic wastewater containing thallium by enhanced coagulation oxidation process. [Method] Enhanced coagulation oxidation process was made use of to remove thallium in the acidic wastewater in the experiment under the condition of 0.05 kg/L of potassium permanganate, 30% hydrogen peroxide and 0.05 kg/L calcium hypochlorite as oxidant, together with 0.092 kg/L CaO as coagulation. [Result] The results showed that thallium removal efficiencies achieved 99.98%, 99.1% and 99.95% when dosages of KMnO4, H2O2and Ca（ClO）2were added at 20, 2.2 and 37 ml, respectively, under the condition of 30 ml 0.092kg/L CaO being dosed and 99.93%, 99.69% and 99.98% were achieved when different dosages of CaO were added at 25, 35 and 25 ml, under the condition of 20ml KMnO4, 2.2 ml H2O2and 37 ml Ca（ClO）2respectively. [Conclusion] The experiment demonstrates that good removal effects of removal thallium from the acidic wastewater would be achieved by enhanced coagulation oxidation process.

The effect of coupling coagulation and flocculation with membrane filtration in water treatment:A review

Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane separation technologies have been identified as one of the possible solutions to meet future demands. Application and implementation of membrane technology is expected both in production of potable water as well as in treatment of wastewater. In potable water production membranes are substituting conventional separation technologies due to the superior performance, potential for less chemical use and sludge production, as well as the potential to fulfill hygienic barrier requirements. Membrane bio-reactor （MBR） technology is probably the membrane process which has had most success and has the best prospects for the future in wastewater treatment. Trends and developments indicate that this technology is becoming accepted and is rapidly becoming the best available technology for many wastewater treatment applications. A major drawback of MBR systems is membrane fouling. Studies have shown that fouling mitigation in MBR systems can potentially be done by coupling coagulation and flocculation to the process.

Purification of AS-CMP effluent by combined photosynthetic bacteria and coagulation treatment

The effluent from the pulping of E. urophylla by alkali sodium sulfite chemi mechanical process(AS-CMP) was characterized for its biodegradability by photosynthetic bacteria (PSB). Chemical coagulation post treatment of biotreated wastewater was also studied. One month continuous treatment in the laboratory indicated that the COD Cr , BOD 5 and SS removals in biotreatment stages reached 56%, 83% and 89% respectively, and the CH 2Cl 2 extractives decreased from 10.7 mg/L to 7.7 mg/L. In chemical coagulation post treatment stage, the effects of process conditions, such as coagulant dosage, pH value and the coordinated coagulation flocculation treatment of three kinds of coagulants on coagulation effectiveness were discussed. The optimum operating conditions were given.