Physicochemical Wastewater Treatment Research Articles

Physicochemical wastewater treatment improvement by hydrodynamic cavitation nanobubbles

Hydrodynamic nanobubble aeration is proposed as an innovative approach to enhancing physicochemical wastewater treatment. Integrating a novel cavitation system to replace conventional aeration significantly improves standard oxygen transfer efficiency and energy consumption. The changes in size and surface charge of air, oxygen (O2), ozone (O3), and chitosan nanobubbles were studied as a function of the reactor diameter. Interestingly, it was found that increasing the radial dispersion length had no significant effect on the measured parameters. Flotation, Coagulation-flocculation (CF), and Advanced Oxidation (AOPs) processes of municipal wastewater comparing convective air and O3 NBs aeration were carried out at pilot plant scale. The use of O3 NBs in the flotation process improves 160 % the suspended solids removal compared to the air-NBs- process. The CF process was evaluated by adding a chitosan dose to the convective processes and monitoring the water quality parameters in real-time. The results demonstrated that the interaction of chitosan with O3 NBs eliminates more than 80 % of the initial chemical oxygen demand (COD). Finally, the AOP carried out with O3 NBs reaches a removal efficiency of 99.8 % total suspended solids and 90 % COD. This modular system presents a practical and efficient alternative for removing municipal and industrial wastewater contaminants.

Leaching behavior and kinetics of beryllium in beryllium-containing sludge (BCS)

Beryllium-containing sludge (BCS) is a byproduct of the physicochemical treatment of beryllium smelting wastewater. The pollutant element beryllium within BCS is highly unstable and extremely toxic, characterized by its small ionic radius and low charge density, resulting in a high risk of leaching and migration. This study is the first to investigate the leaching behavior, influencing mechanisms, and kinetic processes of beryllium in BCS under various environmental conditions. The results indicate that, under national standard conditions, beryllium exhibits a rapid leaching phase within the first 5 h, which then stabilizes after 10 h, with the total leached content significantly exceeding the leaching toxicity identification standards. Under mildly acidic (pH ≤ 5) or highly alkaline (pH = 14) conditions, beryllium demonstrates pronounced leaching and migration behaviors. Notably, in acidic conditions, the leaching rate exceeds 80% within 5 h. Combining the treatment process of beryllium-containing wastewater with analytical methods such as SEM, XPS, ToF-SIMS, and FTIR, it is revealed that due to the heterogeneous nature of BCS, the particle aggregates dissociate over time under acidic conditions. The particle surfaces become increasingly rough, leading to dissolution and the emergence of more reactive sites, resulting in a high proportion of beryllium leaching. Under these conditions, the gradual reaction of Be(OH)2 in BCS to form soluble Be2+ and its hydrolytic complexes is identified as the primary mechanism for extensive beryllium migration. The process encounters minimal diffusion resistance and is classified as reaction-controlled. In acidic conditions with pH = 4, the leaching rate of beryllium significantly increases with rising temperature. The leaching kinetics equation is [(1−x)−0.44]=e(18.26−53050RT)·t, with an apparent activation energy of 53.05 kJ mol−1.

Mineralization of Poly(vinyl alcohol) by Ozone Microbubbles under a Wide Range of pH Conditions.

Poly(vinyl alcohol) (PVA) is a well-known recalcitrant pollutant that threatens ecological systems and human health. In this study, ozone-microbubble treatment was evaluated as a physicochemical method to mineralize PVA in solution for wastewater treatment. Microbubbles are very small bubbles (<50 μm in diameter) and shrink in water because of the rapid dissolution of the interior gas. Ozone microbubbles were generated by a hybrid microbubble generator in PVA solutions with pH conditions of 2, 7, and 10. Ordinary ozone bubbling was also performed as control tests. The change in the total-organic-carbon content was measured to evaluate the efficiency of the system for wastewater treatment. Ordinary ozone bubbling was not able to mineralize aqueous PVA solutions under nonalkaline conditions, and approximately 30% of the total organic carbon remained at pH 2 and 7. Conversely, ozone microbubbles effectively mineralized PVA in aqueous solution to almost 0% in total organic carbon regardless of the pH condition. Effective mineralization of PVA, a recalcitrant organic chemical, demonstrates the potential of ozone-microbubble systems for physicochemical wastewater treatment.

Marble sludges as environmentally friendly catalyst in olive pomace pyrolysis: Effect of sludge composition on pyrolysis product distribution and biochars

Waste management of olive pomace is difficult because of the high production amount and nonbiodegradable organic substances. Catalytic pyrolysis process is one of the effective methods for olive pomace (OP) management and for obtaining valuable organic substances from it. Therefore, in this study, different types of marble sludge were used as catalyst in the olive pomace pyrolysis process at 500°C temperature and 40% catalyst dose. While K1, K2, K3 are the sludges obtained from physicochemical treatment of travertine type marble processing wastewater with alum, FeCl3 and PEL, respectively, K4, K5 and K6 are the corresponding physicochemical treatment sludges of natural stone type marble processing wastewater. Pyrolysis product yields and characteristics of pyrolysis biochars were investigated. The highest product yield for biochar liquid and gas fractions was obtained with the K1 catalyst. The biochar obtained for OP+K1 pyrolysis has the highest initial decomposition temperature. Biochar obtained by using K6 was more granular. Biochar having the highest calorific value (1193 cal/g) was obtained with the catalytic pyrolysis of OP with K4 catalyst. Biochars obtained with the K1 and K6 catalysts has similar calorific values. Besides calorific values, the characteristics of biochars indicated that these biochars can be used diverse purposes either as additive or feedstock. Consequently, K1 catalyst can be recommended for olive pomace catalytic pyrolysis when biochars are evaluated in terms of product yield and biochar characteristics.

Toxic metals and the risks of sludge from the treatment of wastewater from beryllium smelting

The release of highly toxic beryllium in sludge (BCS) produced by physico-chemical treatment of beryllium-containing wastewater from Be smelting production has become a growing concern with the widespread use of Be in the defense industry. This work investigated the potential mobility of Be in BCS. The toxicity characteristic leaching procedure (TCLP) of BCS showed that the amount of leached Be was up to 202 mg L−1, which exceeded the regulated limit by nearly 10,000 times. The chemical fractionation analysis further revealed that the excessive amount of Be leached from BCS was contributed to the high content of acid-soluble fraction and reducible fraction of Be, which accounted for over 70% of the Be content. The results obtained from mineralogical automatic analyzer (MLA) showed that gypsum (23.23%) and epidote (19.55%) were the two major mineralogical phases of BCS. Both were small and loosely structured agglomerated particles with a D50 of 6.61 μm and 3.31 μm. ToF-SIMS results revealed that the Be distribution on the surface of BCS particles was relatively dispersed, with no aggregation or encapsulation. Be co-precipitated with gypsum and chlorite in the form of unstable Be(OH)2, which attached to the surface of these small particles. The unstable state of Be and the small size, loose structure and high liberation of the host material phases are the main reasons for the high leaching mobility of Be. The results of the risk assessment indicated that BCS posed an extremely high potential ecological risk, with Be being the most significant contributor.

Homogeneous ferrous iron oxidation in a pilot-scale electrocoagulation system treating municipal wastewater: a model validation and simulation study.

During an iron-electrocoagulation (Fe-EC) process, floc formation is essential for achieving high contaminants removal. Thus, the complete oxidation of the Fe2+ dosed as coagulant is a critical step for ferric oxides flocs formation. Since the fluctuation in the quality of the influent wastewater affects the kinetics of Fe2+ oxidation, the estimation of optimal operating conditions (i.e. the retention time, dissolved oxygen (DO) concentration, etc.) for high Fe2+ oxidation is required. In this study, the kinetics of Fe2+ oxidation was simulated using PHREEQC software by theoretically optimizing, validating and improving the previously published kinetic models. During model simulation, the process parameters were varied from low to high ranges: Fe2+ dosage (10-100 mg/L) and retention times under the influence of changing pH (7.5-8.2), temperature (12-22 °C), alkalinity (5-10 mEq/L) and initial DO (8.6-10.5 mg/L). Fe2+ oxidation rate was more affected by pH variations in the influent than by temperature variations. A pH increase (+0.4 to +1.7 pH units) was observed due to the low wastewater alkalinity, promoting high Fe2+ oxidation rates. To ensure optimum Fe2+ oxidation levels (≥98%), a minimum retention time of 20 minutes was estimated. Finally, the residual DO concentration should be >3.5 mg/L to avoid a decrease in the oxidation rate. This study contributes to the ongoing research in the field of physico-chemical wastewater treatment with EC by establishing the optimal process parameters required for system optimization and process scalability.

Bio-coagulation using Cicer arietinum combined with pyrolyzed residual sludge-based adsorption for carwash wastewater treatment: A techno-economic and sustainable approach

The physico-chemical treatment of automobile service station wastewater (ASSW) generates large amounts of sludge with toxic compounds, requiring sustainable management practices to protect the environment. To the best of our knowledge, this is the first attempt to maintain the dual benefit of pollution reduction and biochar production via treating ASSW with an integrated coagulation/flocculation/adsorption and sludge pyrolysis system. Using Cicer arietinum powder as bio-coagulant, the optimum coagulation/flocculation factors were pH = 4, flash mixing speed = 170 rpm, and coagulant dosage = 2.26 g/L. This condition provided removal efficiencies of 88.35 ± 4.10 %, 60.30 ± 3.10 %, and 54.25 ± 2.81 % for turbidity, surfactant, and chemical oxygen demand (COD), respectively. Adsorption and inter-particle bridging were the main removal mechanisms involved in treating ASSW using C. arietinum, compared with sweep flocculation using alum. Sludge containing the C. arietinum bio-coagulant was subjected to thermal treatment by pyrolysis to synthesize biochar. This sludge-derived biochar showed promising pore size distribution, and surface morphology and functional groups. Biochar was used as an adsorbent to post-treat ASSW in a fixed-bed column with continuous feed, and the Thomas model exhibited a breakthrough time of 533 min for a designed flow rate of 30 m3/d. The overall removal efficiencies of turbidity, surfactants, and COD for the combined system reached almost 100 %, 99.93 ± 4.31 %, and 93.35 ± 3.88 %, respectively. The integrated physico-chemical and pyrolysis process showed a profitability scenario through wastewater reuse in carwash bays and biochar selling, maintaining a payback period of 5.8 yr.

Development of humic acid based adsorbents for fast and efficient removal of ammonia and organic nitrogen from super magnetic separation treated wastewater

Although super magnetic separation technology (SMS) displayed great potential in removing pollutants from wastewater, the effluent was failed to meet wastewater discharge standard due to relatively high ammonia (AN) and organic nitrogen (ON). In this study, the carbonated and sulfonated humic acid (SCHA) adsorbent was optimally prepared for removing AN from wastewater. Then, based on the carbonated HA with iron loading (CHA-Fe) in our previous study, HA based mixed adsorbent, combining SCHA with CHA-Fe was directly used to simultaneously adsorb AN and ON in wastewater. The optimally prepared SCHA showed fast and efficient adsorption of AN with removal efficiency of around 60% within 40 min, which was ascribed to the function of strong electrostatic interaction by the successfully introduced –SO3-, but cations like Ca2+, Mg2+ and Al3+ significantly reduced AN adsorption. The adsorption data were adjacent with the Langmuir adsorption model with monolayer coverage and pseudo-second-order kinetic model. The calculated maximum adsorption capacity on AN was 12.84 mg/g at 298 K, which was higher than most of the other forms of materials. The thermodynamics of AN adsorption was found to be a spontaneous and exothermic process. In addition, the mixed adsorbent could simultaneously and efficiently adsorb AN and ON from wastewater with the removal efficiency of more than 75% under a wide pH range from 6 to10. It was mainly because the mixed adsorbent could automatically regulate solution pH to neutral range, in which electrostatic adsorption of AN by SCHA and coordinated adsorption of ON by CHA-Fe was intensified. When applied in treating actual wastewater after SMS, the mixed adsorbent could fast and effectively make the wastewater meet the discharge standard (level A) in China (GB18918-2002) through regulating mixed adsorbent dosage. This work provided theoretical and technical basis for physicochemical wastewater treatment processes and developed a new strategy for treating wastewater containing AN and various organics.

A comparison of adsorption of organic micropollutants onto activated carbon following chemically enhanced primary treatment with microsieving, direct membrane filtration and tertiary treatment of municipal wastewater

The adsorption of organic micropollutants onto powdered activated carbon (PAC) was investigated in laboratory scale based on samples from four wastewater process streams (matrices); three from a pilot-scale plant with different degrees of physicochemical treatment of municipal wastewater and one from a full-scale activated sludge plant with post-precipitation. The pilot-scale treatment consisted of chemically enhanced primary treatment with microsieving followed by direct membrane filtration as microfiltration or ultrafiltration. The results showed highest adsorption of micropollutants in the tertiary (biologically and chemically) treated wastewater and lowest adsorption in the microsieve filtrate. Adsorption of micropollutants in the direct membrane microfiltration (200 nm) permeate was generally similar to that in the direct membrane ultrafiltration (3 nm) permeate. The higher adsorption of micropollutants in the tertiary treated wastewater could be related to a lower concentration of dissolved organic carbon (DOC) and lower affinity of DOC for PAC at low dosage (<15 mg PAC/L) in this matrix. At a PAC dose of 10 mg/L, sulfamethoxazole was removed by 33% in the tertiary treated wastewater and 7% in the direct membrane microfiltration permeate. In addition to the PAC experiments, a pilot scale sand filter and a proceeding GAC filter was operated on tertiary treated wastewater from the full-scale treatment plant. Similar removal trends in the PAC and GAC experiments were observed when studying a weighted average micropollutant removal in the GAC filter and a similar dose of activated carbon for both PAC and GAC. Positively charged micropollutants were removed to a higher extent than negatively charged ones by both PAC and GAC.

Очистка поверхностных сточных вод аэропортов

Nowadays the problem of pollution of surface wastewater from the territory of airports with aircraft anti-icing products (ethylene glycol) and products of anti-icing treatment of solid surfaces (formates and acetates) is gaining more and more publicity. The damage to water resourсes can no longer be hidden, since the residents of residential area close to the airport pay attention to dying flora and fauna, changes in the color and smell of the rivers receiving discharged raw wastewater. The lack of understanding among engineering companies of how this problem can be solved gives no way to the airports to do this. An analysis of the world experience of airports related to the treatment of surface wastewater contaminated with ethylene glycol is given. The process flow scheme of biological and physicochemical wastewater treatment developed by the process engineers of «ECOS» JSC, taking into account the regulatory requirements accepted in the Russian Federation, is presented.

PROBLEMS OF SOAPSTOCK TREATMENT OF VEGETABLE OIL PRODUCTIONS AND THEIR SOLUTIONS

Wastewater generated during vegetable oil production contains various pollutants that enter it during soapstock processing: fats and fatty acids and their salts (aqueous soap solutions), glycerin, phosphoglycerates, neutral fat, phosphatides, proteins, carbohydrates, dyes, unsaponifiable and waxy substances, salts, mechanical impurities, etc. Aim. The purpose of the work was to study the processes of purification of industrial wastewater from oil production and to propose an effective technology for their treatment, taking into account the regulatory requirements for the discharge of treated wastewater into the city sewage system. Methods. Chemical oxygen demand (COD) was determined by the dichromate method. The concentration of suspended solids was determined by gravimetric method. Results. As a result of research, calcium carbonate was chosen as an alkaline reagent. After treatment of soapstock with calcium carbonate followed by flotation, the effect of removing the suspended particles was 70–75%, and COD decreased by 60%. On the basis of the research, a technology for processing soapstock was proposed, including sequential processes of physicochemical wastewater treatment —averaging, alkalization with calcium carbonate, stage I of flotation, coagulation, stage II of flotation, oxidation with hydrogen peroxide, filtration through quartz filters and adsorption on carbon filters. Conclusion. An effective technology for preliminary cleaning of the soapstocks oil production has been developed. This will significantly reduce the concentration of organic matter and other pollutants in soapstocks, which will significantly reduce the impact of such effluents on the processes of biological wastewater treatment of urban wastewater treatment plants.

Physicochemical treatment of waste water from complex organic substances

This paper considers with the issues of extracting polycyclic hydrocarbons from wastewaters by using physicochemical technology, including the use of flotation, settling, filtration, adsorption, ozonation. The usage of this technology could significantly reduce the concentration of such hazardous substances as benzopyrene in the treated wastewaters. Under certain regimes of wastewaters treatment using physicochemical technology, the concentration of benzopyrene does not exceed the standard values. The prospects for the usage of bio-flotation harvesters for the treatment of wastewaters, which contains complex organic substances are indicated.

Phosphate removal from food industry wastewater by chemical precipitation treatment with biocalcium eggshell

The physicochemical treatment (PT) of food industry wastewater was investigated. In the first stage, calcium magnesium acetate (CaMgAc4) was synthesized using eggshell (biocalcium), magnesium oxide and acetic acid in a 1:1:1 stoichiometric ratio. In the synthesis process, the thermodynamic parameters (ΔH, ΔS and ΔG) indicated that the reaction was endothermic and spontaneous. The samples were characterized by infrared spectroscopy (IR), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and electron X-ray dispersive spectroscopy (EDS). CaMgAc4 was used to precipitate the phosphate matter. IR analysis revealed that the main functional groups were representative of the acetate compounds and the presence of OH− groups and carbonates. In the physicochemical treatment, a response surface design was used to determine the variables that influence the process (pH, t, and concentration), and the response variable was phosphorus removal. The treatments were carried out in the wastewater industry with an initial concentration of 658 mg/L TP. The optimal conditions of the precipitation treatment were pH 12, time 12 min, and a CaMgAc4 concentration of 13.18 mg/L. These conditions allowed the total elimination (100%) of total phosphorus and phosphates, 81.43% BOD5 and 81.0% COD, 98.9% turbidity, 95.01% color, and 92% nitrogen matter.

Physicochemical and electrocoagulation treatment of wastewater from a cardboard packaging company

The diagnostics of the physicochemical treatment and electrocoagulation plant of the cardboard packaging company showed that currently, the wastewater has a COD of 18,000 mg/L and suspended solids of 2425 mg/L, therefore, it does not comply with the maximum permissible limits stipulated in nom-001-semarnat-1996. It was found that the physicochemical treatment has a removal efficiency of 33% for COD and 58% of total solids; while the electrocoagulation stage has a negligible effect. In the physicochemical treatment tests, a removal of 92% of the COD was obtained and in the treatment by electrocoagulation, a removal of 37.5% of the residual COD from the previous stage was achieved. This information shows that both treatments can be viable alone or in combination. Objectives: Evaluate the physicochemical treatment and electrocoagulation of wastewater of a company that produces cardboard packaging. Methodology: 1. Develop characterization of wastewater, 2. Develop treatability tests through physicochemical treatment, 3. Develop treatability tests by electrocoagulation treatment, 3. Analyze results. Contribution: This project allowed to know the efficiencies of COD removal, which can be had with the physicochemical treatment, with the treatment by electrocoagulation and with the combined treatment; as well as their optimal conditions in each case. This made it possible to generate operating proposals, which allow reducing operating costs and increasing treatment efficiency.

Physico-chemical Wastewater Treatment from Complex Organic Substances Using Flotocombs

The issues of extraction of complex organic substances from wastewater using physico-chemical methods of coagulation, flotation, adsorption. At the same time, flotation combines of the KBS type are used at the flotation stage, which make it possible to effectively treat wastewater from suspended pollutants and complex organic substances. At the stage of sorption treatment, a deep extraction of complex organic substances occurs up to trace amounts, which allows to achieve the normative quality of water treatment with the possibility of discharge into an open reservoir.

Physico-chemical treatment of waste water contaminated with heavy metals in the industry of metallic coatings

AbstractThis investigation was undertaken to determine the optimum conditions for physical-chemical treatment of waste water contaminated with heavy metals in the industry of metallic coatings. The industry uses substances such as: inorganic acids, alkalis, acidic and alkaline metal salts, that has a high water demand in the processes of flushing and cleaning the parts to be coated. According to the preliminary characterization of samples and reported in the literature theory, physico-chemical process was implemented for the removal of contaminants that consisted in chemical oxidation of CN-ions, followed by chemical precipitation made next to a coagulation/flocculation and subsequent adsorption on activated coal. Laboratory scale tests showed the optimal conditions of treatment including chemical oxidation by the addition of 4.15 cm3 of H2O2 (30%) per gram of CN, chemical precipitation with NaOH to a pH of 12, followed by coagulation/flocculation with Fe2(SO4)3 at a speed of 135 rpm for 3 min and 20 rpm for 20 min and finally the addition of 1.0 g of adsorbent previously activated at 700°C. From this study, it is clear that the adsorption on activated carbon is highly efficient in the removal of heavy metals from industrial waste water from electroplating. However, it is also clear that the parallel application of the treatments, shown here, is more effective to completely remove contaminants such as lead, nickel, silver, and copper at laboratory scale, so it is recommended the simultaneous use of these physico-chemical processes.

Removal of inorganic chemical species and organic matter from slaughterhouse wastewater via calcium acetate synthesized from eggshell

The physicochemical treatment (PT) of slaughterhouse wastewater (SWW) was investigated. In the first stage, calcium acetate (Ca(Ac)2) was synthesized in five different ways: (1) acetic acid (HAc) and chicken eggshell (CaAc1), (2) lime (CaAc2), (3) a 1:1 eggshell and lime mixture (CaAc3), (4) a 1:2 eggshell and lime mixture (CaAc4), and (5) calcium oxide via the calcination of eggshell (CaAc5). The synthesized Ca(Ac)2 samples were characterized by IR, SEM, XRD, and EDS. Subsequently, the samples were used to precipitate oxyanions and organic matter. The experiments were carried out at pH 4 and 12. For the treatment with CaAc1 at pH 4, an acid (HCl, H2SO4, or HAc) was also added. The best results for CaAc1 in acid media were attained with HCl, where removal efficiencies of 82.23% total suspended solids, 76% turbidity, 81.43% color, 53.86% Fe, 69.74% Cu, and 14.64% Na were observed. This treatment also removed ∼99% fecal and total coliforms, 26.49% COD, and 78.39% TOC. The experiments were also performed at pH 12 using CaAc1. These afforded removal efficiencies of 92.7% turbidity, 84.7% color, 40.5% phosphates (PO43–), and 64.7% sulfates (SO42–). In addition, this method removed metals, 35.37% COD and 99% fecal and total coliforms.

Applicability of water-spray electric arc furnace steel slag for removal of Cd and Mn ions from aqueous solutions and industrial wastewaters

Adsorption is a fundamental process in the physicochemical treatment of wastewaters which industries employ to reduce hazardous organic and inorganic wastes in effluents. The main objective of this study is to find a suitable application of the water-spray electric arc furnace (WS-EAF) slag which is a by-product of the steelmaking process. This material was collected, crushed, milled and characterized in terms of chemical composition, morphology and phases. The results showed that the main phases of the WS-EAF slag were magnetite (Fe3O4), wustite (Fe0.94O), beta-calcium silicate (Ca2SiO4) and mayenite (Ca12Al14O33). Several parameters were applied to evaluate the performance of WS-EAF slag for removal of Cd (II) and Mn(II) from aqueous solutions and wastewaters. Adsorption kinetics of Cd and Mn ions has been discussed. The applicability of WS-EAF slag for removal of other heavy metals (Zn, Fe, Ni, Pb and Co) from wastewaters has also been examined. The best parameters to achieve 99.99 and 99.96 (%) removal for Cd and Mn ions from aqueous solutions were found to be 10 μm adsorbent particle size, 0.5 g adsorbent weight, 8 solution pH, 90 min contact time, and 10 mg/L initial metal ions concentration at room temperature. Pseudo second-order model fits well with data of Cd and Mn adsorption. The WS-EAF slag appears to be a promising material for removal of competitive heavy metals from industrial wastewater via adsorption.

Physicochemical treatment of industrial wastewater using &lt;i&gt;Moringa peregrina&lt;/i&gt; as a coagulant for flocculation: a comparative study

Optimum conditions for applying M. peregrina as a natural coagulant to treat pharmaceutical wastewater are determined and compared with that of alum coagulation. In both cases, coagulation, flocculation, sedimentation, was followed by slow sand filtration and activated carbon adsorption treatment. Alum reduced COD, BOD5, TSS and turbidity by 48.6%, 34.8%, 79.6%, and 69.2% respectively. Alum coagulation followed by slow sand filtration reduces the studied parameters by 97.7%, 95.7%, 93.9% and 76.9% respectively. Activated carbon was used to further reduce these parameters to 99.9%, 99.1%, 94.3% and 81.3% respectively. While using M. peregrina excellent reduction in studied parameters was found as 81.7%, 83.2%, 78.6% and 94.2% respectively. Further physicochemical treatment reduced by 99.8%, 99.7%, 99.1%, and 92.3% respectively after SSF. The performance of M. peregrina found to be superior to that of alum coagulation and can bring wastewater quality up to the standard allowable limits for reuse.

Cost-effective physicochemical treatment of carpet industrial wastewater for reuse

The main objective of this study is to investigate the efficiency of the physicochemical treatment process for removal of hazardous refractory wastewater from carpet industry. Characteristics of carpet industry wastewater in terms of COD, BOD, TSS were 60000, 110, 9800 mg/L. Their complete biodegradation is usually very slow as indicated from the immensely low value of BOD/COD, 0.002.High TSS promote the coagulation/flocculation in which coagulants such as ferric chloride, ferrous sulfate and flocculent are added to wastewater in order to destabilize the colloidal materials, eliminate as much as possible of suspended solids and organic materials. The results showed that ferric chloride (1.2g/l), flocculent (2mg/L) at pH 8 achieved COD removal efficiencies of 97% whereas using ferrous sulfate (1.8 g/l), flocculent (2 mg/L) at pH 7 achieved 98% COD removal. Corresponding TSS removal values were 96 and 97%, respectively. Furthermore, lamellar sedimentation of the treated effluent followed by sand filtration upgrades the finally treated effluent for recycling inside the factory, the residual COD and TSS were70 and5mg/L respectively.The construction cost of the treatment unit (100 m3/d) is about US$ 26000 and the running cost is about US$ 3300/year, providing a saving of about US$ 8064/year.