Laundry is the procedure to do certain that fabrics are washed and cleaned once more after it being used and become dirty. A merchandise that included of wash is normally similar detergents, bleaches, builders, and metal chelating agents. Laundry effluent contain in sewerage. It releases big sums of chemicals into effluent. Toxic chemicals in this substance are wetting agents, Cl, organic peroxides, phosphates, base, and ethanediol quintessences.

2.1.1 Detergents

Detergent is one of substance that contributes big sums of laundry effluent. Detergent is substance that comfy to rinsing fabrics as active cleansing agent. It is rather effectual for the procedure of rinsing when set it in signifier of aqueous solution. There is two group contain in detergent which that hydrophobic ( non polar in signifier of tail ) and hydrophilic molecule ( as polar caput ) which means they will assail a dirty on fabrics during the

procedure of rinsing. The hydrophobic group is unable base with stable construction and it is unfriendly with H2O molecule while hydrophilic is to like be concerted with H2O. In this instance, polar caput is interact with H bonds and hydrophobic dress suits aggregate ensuing in extremely organized will organize spherical construction that being called as micelles. The detergents are existed as individual molecule at low concentration. The concentration additions micelles begin to organize. The concentration at which micelles Begin to organize is known as the Critical Micelle Concentration ( CMC ) ( a ‘ Hartmann, 2006 ) .

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Figure 2.1: A detergent micelle formed with Sodium Dodecyl Sulfate molecules in an aqueous solution ( left ) or a non-aqueous solution ( right ) ( Beginning: B ‘ Hartmann, 2006 ) .


In this position, two parametric quantities for H2O quality will be learned as follow the range of survey. There is turbidness and pH. In Malaysia, the authorities declared that two of the characteristic are including in the parametric quantities for standard H2O quality. They already stated at a graduated table based on categories.

Table 2.1: National Water Quality Standards for Malaysia based on two parametric quantities ( beginning: Department of Environment, 2001 ; 2002 ; 2003 )



Unit of measurement


















2.2.1 Turbidity

Turbidity is one of a chief physical feature in belongingss of H2O quality. As the simple account, it is the step of comparative lucidity of liquid. It is an look of the optical belongings that causes visible radiation to be scattered and absorbed by atoms and molecules instead than transmitted in consecutive lines through a H2O sample ( EPA Guidance Manual Turbidity Provisions, 1999 ) . This turbidness is occurred because a present of suspended affair or drosss that interfere with the lucidity of the H2O. These drosss that form the

turbidness likely include silt, whether organic or inorganic affair, clay, plankton and other microscopic beings.

2.2.2 pH

Distance is measure by Kilometre, the clip is measure by hr, the grade of sourness or basicity of a solution is measure by pH unit ( Frederick, 2003 ) . pH is the measuring of a H ion concentration, [ H+ ] where the ion is contain in an aqueous solution. The scope of step for pH is from 0 to 14 pH. If the solution is below than 7 pH, it will see as acidic belongingss while above than 7 pH really called basic belongingss which is besides known as acerb or alkalic belongingss. Since the value precisely at the Centre of measuring ( 7 pH ) , it is “ impersonal ” which means neither acidic nor basic. pH is genuinely defined as the negative logarithm of [ H+ ] .

pH is importance for aquatic beings to be within their H2O organic structure because a certain scope of pH is need for endurance and besides for optimum growing. Even each being has suited pH to populate, the scope of pH from 6.5 to 8.0 are being preferred for most aquatic beings. Outside of this scope, organisms become physiologically stressed ( Kelly et al. , 2004 ) . Other than that, reproduction can besides be impacted, and life of beings is opened to decease if the pH is non in the optimum scope. The lower of pH step can do a toxic elements and compound are released from deposits into the H2O. In this state of affairs, aquatic animate beings will take the toxic. The handiness of works foods are influence by the alteration of pH metre excessively.


Advanced Oxidation Processes ( AOPs ) is the chemical procedure by utilizing oxidization. It is utilizing hydroxyl extremist, OHaˆ? as oxidising agent for intervention H2O. To bring forth OHaˆ? , There are several method based on AOPs. There are such as Ozone method, Photocatalysis, and Fenton reaction. AOPs have ability to oxidising complex organic components that found in H2O which is to hard to biodegrade them ( a ‘ Metcalf and Eddy, 2004 ) .

Table 2.2: The potency of oxidising agents ( beginning: Ozonia, 1997 )

Oxidising agent

Electrochemical Oxidation Potential ( EOP ) , Volt

EOP that relative to Chlorine, Cl

Fluorine, Fl



hydroxyl extremist, OHaˆ?



Oxygen, ( atomic )



Ozone, O3



Hydrogen Peroxide, H2O2






Chlorine, Cl



Chlorine dioxide, CO2



Oxygen, O2



Based on Table 2.2, there are few assorted oxidising agent that normally used in the debasement ‘s procedure of H2O ( B ‘ Metcalf and Eddy, 2004 ) . Hydroxyl extremist is 2nd highest of powerful oxidising agent after Fluorine, Fl. Even though Fluorine is the powerful than hydroxyl extremist, the cost is high and non commercial to be used in handling effluent.


2.4.1 Fenton reagent

The Fenton reagent has two ions that can be react with organic to procedure of intervention. There is Ferric, Fe ( II ) and H peroxide, H2O2 that consist in the system of Fenton under acidic status. Fenton is the methods that effectual for the devastation of any sort of waste such toxic waste, laundry waste and non-biodegrable. This method is more effectual and besides more suited instead than secondary biological intervention ( Chen & A ; Pignatello, 1997 ) . Other than that, Fenton is besides usage to handle a assortment of wastes such as the fabric industry, chemical fabrication, and fuel terminuss ( Polish, 2005 ) .

Basically, Fenton is one of method intervention of advanced oxidization procedure ( AOP ) because it treats the H2O by Hydroxyl extremist through the oxidization procedure. There is another method of oxidization utilizing the Fenton but it is advanced measure of Fenton to handle the waste H2O. It is called Electro-Fenton Process ( EFP ) . This method is considers to be include in electrochemical method or electrolysis method. EFP likes to be the adding of electrochemical setup and cell to carry on this technique. The research about EFP has been done by Elodie ( 2003 ) which are to degrade azo dye, electro Fenton procedure is efficient for the procedure.

2.4.2 Hydroxyl extremist formation

Fenton ‘s reagent is known as a precursor of the hydroxyl extremist OHaˆ? a extremely oxidizing agent. Fenton that contain both of substances is reacted each other to organize hydroxyl extremist which means it should follow a certain mechanism. The mechanism is called hydroxyl mechanism. Two old ages after Fenton ‘s decease the hydroxyl mechanism was mentioned by Haber and Willstatter ( 1931 ) in a paper on extremist concatenation mechanism. This mechanism that be shown is a first measure reaction of Fenton chemical science. The measure reaction of this mechanism include in extremist mechanism. The other mechanism is non-radical mechanism. Following Barb et. Al ( 1951 ) , the stairss of free extremist mechanism following by these:

Fe2+ + H2O2 Fe3+ + OH- + OHaˆ? ( 1 )

Fe2+ as contact action reacts with H peroxide to bring forth hydroxyl groups.

OHaˆ? + H2O2 HO2aˆ? + H2O ( 2 )

The hydroxyl group has the inclination to respond with Hydrogen Peroxide to bring forth hydroperoxyl extremist. Hydroperoxyl extremist is weaker oxidising agent compared to hydroxyl groups ( a ‘ Mohajeri et Al, 2010 ) .

Fe3+ + HO2aˆ? Fe2+ + H+ + O2 ( 3 )

Fe2+ will renew through this reaction. By the manner, the other reaction for regeneration of Fe2+ will be discussed in item in following subdivision.

Fe2+ + HO2aˆ? Fe3+ + HO2- ( 4 )

Fe2+ perchance can respond with hydroperoxyl extremist to bring forth an sum of Fe3+ .

Fe2+ + OHaˆ? Fe3+ + OH- ( 5 )

Fe2+ will respond with hydroxyl groups which that sum of Fe3+ is produce once more.

Based on equation ( 1 ) , interaction between Fe2+ and H2O2 are bring forthing OHaˆ? groups. OHaˆ? group has a great oxidising ability to degrade toxic organic contaminations ( Walling, 1975 ) . OHaˆ? extremist will respond with organic substrates that contain in waste H2O. The debasement of organic compound are faster than usual if the sum of Fe2+ is present in big sums because it will bring forth more OHaˆ? group.

2.4.3 Regeneration of Fe ( II )

Fe ( II ) besides regenerated through the reaction of Fe ( III ) with H2O2 in the alleged Fenton-like-reaction. The procedure regeneration of Fe2+ is occurred when Fe3+ and HO2aˆ? extremist are react each other as the mentioned in equation ( 2 ) . By the manner, the to the full reactions to generated Fe2+ through Fenton-like-reaction follow by this:

H2O2 + Fe3+ FeOOH2+ + H+ ( 6 )

FeOOH2+ HO2aˆ? + Fe2+ ( 7 )

HO2aˆ? + Fe2+ HO2- + Fe3+ ( 8 )

HO2aˆ? + Fe3+ H+ + O2 + Fe2+ ( 9 )

Three reactions can renew Fe2+ . Actually, the equation ( 9 ) and ( 3 ) are the same. And besides for equation ( 8 ) and ( 4 ) are similar equation. In this instance, Fe2+ will oxidise to Fe3+ through any reaction can be occurred such as in equation ( 1 ) , equation ( 4 ) or ( 8 ) and equation ( 5 ) . But, to regeneration of Fe2+ , it can go on when the sum of Fe3+ reacts with Hydroperoxyl group.

2.4.4 Chemical reaction between hydroxyl groups and organic affair.

After the procedure to bring forth hydroxyl groups, the group will degrade organic affair in laundry effluent:

RH + OHaˆ? Raˆ? + H2O ( 10 )

Raˆ? + Fe3+ R+ + Fe2+ ( 11 )

Based on all the equations, the Fenton procedure is efficient if the hydroxyl extremist that produce in big sum. By the manner, to bring forth the extremist, it is demands and requires a high concentration Fe2+ because one molecule of Fe2+ is consumed to bring forth the each of hydroxyl extremist ( Rein, 2001 ) .


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