Phosphate removal from phosphorus containing wastewater by coagulation/flocculation process using Gossypium spp. (GS) as coagulant

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1 Phosphate removal from phosphorus containing wastewater by coagulation/flocculation process using Gossypium spp. (GS) as coagulant K.A Babayemi* 1, O.D. Onukwuli 1 Department of chemical Engineering, Anambra State University, Nigeria Department of chemical Engineering, Nnamdi Azikiwe University, Nigeria Corresponding author; K.A Babayemi; akinbabs@yahoo.com Abstract: Phosphate removal from phosphorus containing effluent was carried out using bio-coagulant. Gossypium Spp (cotton seed) an ecofriendly biomass was used as a coagulant in this work for the wastewater treatment through Nephelometric method. The study evaluates the coagulation/flocculation efficiency of GS. Parameters such as ph levels of the effluent, dosages of GS and settling time were varied. Statistical (via 3 Central Composite Design, CCD) modeling for process optimization was carried out. The results obtained showed that, maximum coagulation performance E(%) >7 was obtained at mg/l GS concentration and ph=6.the most significant main effect for performance of GS as a coagulant is its dosage (P value =.6) while ph (P value =.7) is the least significant. Keyword:Phosphate;Coagulation/Flocculation; Biomass; Gossypium Spp.; Phosphorus; Effluent I. INTRODUCTION Coagulation and flocculation provide the water treatment process by which finely divided suspended and colloidal matter in the water is made to agglomerate and form flocs. This enables their removal in subsequent sedimentation and filtration stages.[1].coag-flocculation of wastewater may be accomplished with any of the common water coagulants including lime, iron and aluminum salts and synthetic polymers. However, the search for a better alternative to conventional coagulants has become an important challenge in the water treatment process with the aim of minimizing the detrimental effects associated with the use of such coagulants. The use of coagulants of biological origin has become essential. Some of the coagulants and flocculants of biological origin that have been used include chitosan [] tannins [3], aqueous extract of the seed of Moringa Oleifera [], extracts of Okra, nirmali seed[5] and cotton seed (Gosspium Spp) which is the subject of the study. Cotton is currently the leading plant fibre crop worldwide and is grown commercially in the temperate and tropical regions of more than fifty countries [6] Cotton is primarily grown as fibre crop. It is harvested as seed cotton which is then ginned to separate the seed and lint. The delinted cotton seed can be processed to produce oil, meal and hulls. Oil produced from the seeds has achieved GRAS (Generally Recognized As Safe) status under the United States Federal Food Drug and Cosmetic Act [7]. They are also used as a viscosity enhancer (thickener) in ice cream, salad dressing and tooth paste [8]. TABLE1: CHARACTERIZATION RESULT OF WASTE WATER EFFLUENT BEFORE AND AFTER TREATMENT Parameter S.I. Unit Before coagulation After coagulation Colour Hazen 18. ph 8. Conductivity µ/ cm Turbidity Not clear Mil clear Total solid mg/l Acidity mg/l Alkalinity mg/l 85 5 manganese mg/l potassium mg/l 1.8 Chloride mg/l nitrogen % Chemical oxygen demand mg/l Dissolved Oxygen mg/l Biochemical oxygen demand mg/l Sulphate mg/l Nitrate mg/l.1 - copper mg/l 1 - Phosphorus mg/l Total Hardness mg/l lead mg/l.9 - magnesium mg/l Iron mg/l.75 - Volume 3 Issue 1, Feb.15 PP American V-King Scientific Publishing 1

2 Current Advances in Environmental Science Therefore, biodegradability, non-toxicity supported by thickening properties present the organic derived coagulant with extensive application in water treatment technology. Although GS is available in large quantities in Nigeria, no work has been reported on its coagulation/flocculation application particularly to the removal of phosphates from wastewater. This work therefore, attempts to utilize the potentiality of GS as a coagulant. 7 7 mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l Fig. 1: Coagulation efficiency profile for varying GS dosage at ph= Fig.11: Coagulation efficiency profile for varying GS dosage at ph= Fig. : Coagulation efficiency profile for varying GS dosage at ph= Fig.119: Coagulation efficiency profile for varying GS dosage at ph= 7 7 mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l Fig. 3: Coagulation efficiency profile for varying GS dosage at ph=6 7 Fig.1: Coagulation efficiency profile for varying GS dosage at ph=6 Fig. : Coagulation efficiency profile for varying GS dosage at ph=8 Fig.19: Coagulation efficiency profile for varying GS dosage at ph=8 mg/l mg/l mg/l mg/l mg/l 1 Dosage (mg/l) ph Fig.13: Coagulation efficiency profile for varying GS dosage at ph= Fig. 5: Coagulation efficiency profile for varying GS dosage at ph= Fig.6: 3-D Surface Plot for GS Showing Turbidity, Dosage and ph Volume 3 Issue 1, Feb.15 PP American V-King Scientific Publishing

3 Current Advances in Environmental Science Time (mins) ph Time (mins) Dosage (mg/l) 1 Fig. 7: 3-D Surface Plot for GS Showing Turbidity, Time and ph Fig. 8: 3-D Surface Plot for GS Showing Turbidity, Time and Dosage Model Predictions Experimental Results Experimental Results Fig. 9: Experimental vs. Model Predictions for Coagulation using GS II. MATERIALS AND METHODS The sample of seed cotton was sourced from a community market at Molete Ibadan, in Oyo State. The seeds were ginned and the linters removed before drying to reduce the moisture content. The dried seeds were ground and processed into a coagulant using standard method [9, ]. The jar test was conducted based on standard Bench scale Nephelometric method for the examination of water and waste water [11, 1] using model WZS 185MC Turbid meter, Gulenhamp magnetic stirrer and Delta 3 ph meter. The percentage of turbidity removal was calculated using equation (1) Removal efficiency E(%) = C C 1 x. (1) C Where C and C 1 are the initial and residual concentration of phosphorus in the waste water effluent respectively(mg/l).statistical Central Composite Design (CCD) with a 3 full factorial design is employed. The standard CCD is constructed from a m- designs for the cube portion, which is augmented with centre points and star points. Number of experimental points (N) for CCD is N= m-t +m+n o.where, m is the number of variables (here m=3; x 1,x,x 3 ), t is the degree of fractionality (t=, since m is not greater than ), N o is the centre point (N o is chosen to be 3), ph, dosage and settling time are independent variables while the output response is the Turbidity removal. III. RESULTS AND DISCUSSION Volume 3 Issue 1, Feb.15 PP American V-King Scientific Publishing 3

4 Table. shows the characterization results of the GS coagulant. In all the analyzed parameters (moisture content, ash content, lipid content, crude protein, carbohydrate and crude fibre) protein happens to be the active agent responsible for the coagulation in these substrates. The percentage protein content of GS is.31%. Wastewater effluent was characterized before and after treatment, and the results obtained are presented in Table.1. The result of the wastewater sample indicates that some heavy metals such as iron, lead and copper which are.75mg/l,.9mg/l and 1.mg/l before treatment respectively were totally removed during the coagulation process. Between 85% and 91% of magnesium, sulphates, chlorides, and phosphates were also removed during the process.fig.1 to 5 show the effect of the coagulant dosage on turbidity removal at various ph. It can be observed from the figures that the removal of turbidity increases with increase in coagulant dosage. Figs.1-3 show the removal efficiency as a function of time for various GS coagulant dosages at ph of, and 6 respectively. The main attribute to effective performance of GS as a coagulant is its dosage (P value =.6) while ph (P value =.7) is not that effective. Changes in dosage have a major impact on the effectiveness of a coagulant while ph has the least effect. The parameter of ph(x 1 ) and its quadratic effect (x 1 ) may be excluded from the model without having any major effect on the accuracy of the model. The model accuracy is validated by the values of R (.9363) and Adjusted R (.817) and closeness of the predicted values to the actual experimental values. The surface response plot revealed a higher quadratic profile for dosage and least for ph as presented in Fig.6. The model fits for coagulation using GS is given as; Y= x x +1.61x 3 +.7x 1 x +.687x 1 x x x x x -.3x 3. Where Y is the turbidity and represents the dependent variable in the model equation while the independent variablesx 1, x, x 3 are the coded values for ph, dosage and time respectively. TABLE : CHARACTERIZATION RESULTS OF COAGULANT Parameter GS Moisture content (%) 9.85 Ash content (%).15 Lipid content (%) 1. Crude protein (%).31 Carbohydrate (%) 5. Crude fibre (%) 18.9 IV. CONCLUSIONS The statistical modeling of the process has established that a change in dosage has the greatest effect in the effectiveness of GS coagulant while a change in ph has the least effect. The high removal efficiency of GS, E(%)>7, availability, biodegradability and non-toxic nature present the potential of GS as a source of organic derived coagulant applicable in large scale water treatment. NOMENCLATURE CCD: Central Composite Design x 1 : Coded value for ph x : Coded value for Dosage x 3 : Coded value for Time GS: Gossypium Spp C: Residual concentration of phosphorus in the waste effluent, mg/l C : Initial concentration of phosphorus in the waste water, mg/l REFERENCES [1] Jia-Qian Jiang, and Nigel; J.D Graham, 1998, Observations of the comparative hydrolysis/precipitation behavior of poly ferric sulphate and ferric sulphate, Water Res. (3) [] Ozacar, and Sengli A,, Effectiveness of tannins obtained from velunia as a coagulant aid for dewatering of sludge, Water Res. 3 (), Volume 3 Issue 1, Feb.15 PP American V-King Scientific Publishing

5 [3] Ndabigengesere, A. and Narasiah, K.S, 1998, Quality of water treated by coagulation using Moringa Oleifera seeds, Water Res. Vol. 3, No 3, pp [] Oladoja, M.A and Ahu Y.D, 8, Evaluation of Plantain peelings ash extract as coagulant of colloidal particle in low ph aqua system, Water Quality Research Journal, Canada. [5] Roberts G.A.F, 1997, Adv. Chitin Sci II, Proceedings of the 7 th International Conference on Chitin R Chitoson, Lyons. [6] Smith, A. 1, The use of sludge from mine drainage settling ponds containing different levels of phosphate as a substrate for the growth of barley, B.Sc Thesis, Institute of Ecology and Resource Management, Univ. of Edinburgh. [7] ANZFA,, Draft Assessment Report (Full assessment S15) Application A36; oil and linters derived from insect-protected cotton containing event 15985, Full assessment Application A36, Australia New Zealand food Authority, Canberra, Australia. [8] Gregory S.R, Hernandez E, Savoy B.R, 1999, Cotton seed Processing, In WC Smith, JT Cothren, eds Cotton: Origin, History, Technology and Production, pp [9] Fernandez-Kin,, Physio chemical and functional properties of craw fish chitosan as affected by different processing protocols, M.Sc Thesis, Louisiana State University and Agricultural and Mechanical College, U.S.A. [] Ani J.U, Menkiti M.C, and Onukwuli O.D, 9, Coagulation and flocculation behaviour of snail/shell coagulant in fibre-cement plant effluent, J. Eng. Appl. Sci. vol. 67,. [11] Water Specialist Technology (WST), 3, About coagulation and flocculation, Information Bulletins, U.S.A, pp 1-. [1] AWWA, 5, Standard Methods for the examination of water and waste water effluent, New York, U.S.A. Volume 3 Issue 1, Feb.15 PP American V-King Scientific Publishing 5