Moringa Oleifera seeds and Chitosan as alternatives to conventional coagulation agents

IOP Con e ence Se ies: Ma e ials Science and Enginee ing PAPER • OPEN ACCESS Mo inga Olei e a seeds and Chi osan as al e na i es o con en ional coagula ion agen s To ci e his a icle: T Kue a and L Ho mano á 2020 IOP Con . Se .: Ma e . Sci. Eng. 800 012032 View he a icle online o upda es and enhancemen s. This con en was downloaded om IP add ess 147.229.25.109 on 18/06/2020 a 13:31 Con en om his wo k may be used unde he e ms o heC ea i eCommonsA ibu ion 3.0 licence. Any u he dis ibu ion o his wo k mus main ain a ibu ion o he au ho (s) and he i le o he wo k, jou nal ci a ion and DOI. Published unde licence by IOP Publishing L d 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 1 Mo inga Olei e a seeds and Chi osan as al e na i es o con en ional coagula ion agen s T Kuče a1*, L Ho mano á1 1B no Uni e si y o Technology, Facul y o Ci il Enginee ing, Ins i u e o Municipal Wa e Managemen , Žižko a 17, B no, 602 00, Czech Republic. *Email: omas.kuce a@ u .cz Abs ac . This a icle discusses he possibili ies o using na u al polyme s in he wa e ea men p ocess o eplace con en ional chemical-based eagen s. Mainly pa o a icle p esen ed he esul s o a labo a o y-scale esea ch ocused on he use o al e na i e coagulan s in wa e ea men . A en ion was pa icula ly paid o na u al ca ion coagulan s de i ed om Mo inga olei e a seeds and chi in. These wo coagulan agen s we e used in labo a o y esea ch o ea ing eal aw wa e . Se e al se ies o labo a o y ja es s we e pe o med o iden i y he e ec i eness o he selec ed coagulan s in emo ing u bidi y om wa e . 1. In oduc ion The in oduc ion o a coagula ion p ocess is o en equi ed o ea ing wa e om su ace sou ces o dec ease u bidi y and colo , as well as he olume o pa hogenic o ganisms. The p ocess may also be op imized o he emo al o na u al o ganic ma e (NOM) and hea y me als [6]. Va ious coagulan agen s a e used o he p ocess and he selec ion o a sui able coagulan depends upon he ype o subs ance emo ed, as well as he o e all wa e ea men p ocess [8]. Coagula ion may be combined wi h o he physical, chemical o biological p ocesses. Coagulan s a e p ima ily di ided in o he o ganic and ino ganic. Ino ganic coagulan s a e me al sal s, o possibly in a hyd olyzed polyme o m. O ganic coagulan s a e a ailable in many ypes o subs ances and c ea e long chains. Coagulan s may u he be di ided based on hei cha ge in o ca ion and anion and, acco ding o hei o igin, di ided in o syn he ic o na u al. Sal s o aluminum and i on appea o be mos comme cially success ul. Howe e , in ecen yea s, polyme coagulan s a e also used [25], mos o en as auxilia y agen s used o inc ease he e iciency o wa e ea men on he one hand and dec ease cos s on he o he . Va ious coagulan s display di e ing e iciency in des abilizing indi idual pollu an s [18]. The e o e, he p ope ies o he aw wa e mus be known in o de o es ablish he ype and olume o he necessa y coagulan . The deg ee o concen a ion also a ec s he po ency o hei coagula ion. Choice o coagulan s p ima ily depends upon he composi ion o he wa e ea ed, including i s pH, empe a u e, oxida ion- educ ion po en ial, olume o subs ances suspended in he wa e , e c. The choice o an op imal des abiliza ion agen mus always be made based on labo a o y es s, ideally by es ing unde pa ial ope a ing condi ions. The size o loccules is he majo physical pa ame e a ec ing he ea men p ocess. Ano he impo an p ope y is he esis ance o hese loccules o decomposi ion in o smalle pa s. Smalle pa s dec ease he e ec i eness o he subsequen sepa a ion, as hey se le mo e slowly han la ge pa icles o simila densi y [18]. 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 2 2. Ino ganic coagulan s, hei p ope ies and use 2.1. Me al coagulan s Me al sal s a e p obably he mos equen ly used coagulan s in p ac ical wa e ea men . These a e mos o en i alen compounds o aluminum and i on [8]. The e ec i eness o hei coagula ion is a ec ed by dosage, he me hod o homogeniza ion, pH and he p ope ies o he subs ance emo ed [29]. Wa e empe a u e is also an essen ial ac o o hei unc ion [9], pa icula ly in he case o aluminum- based coagulan s. Sa is ac o y coagula ion e ec i eness will no be achie ed a low empe a u es du ing he colde pa o he yea , e en by inc eased doses o he agen . Ino ganic coagulan s a e ypically dosed in highe concen a ions, esul ing in he p oduc ion o a la ge olume o sedimen . A ce ain amoun o he me al ca ion o he espec i e sal emains in such ea ed wa e . Me al coagulan esidues alone pose ce ain heal h and/o en i onmen al isks. The disad an ages o ino ganic sal s, along wi h hei sensi i i y o seasonal changes in he physical p ope ies o aw wa e (pH and empe a u e) as well as hei minimal e ec i eness in emo ing ine pa icles, b ough a demand o di e en ypes o coagulan s. E ec i eness is imp o ed by polyme iza ion o ino ganic coagulan s and hei use in wa e ea men [29]. Examples o me al coagulan s used in wa e ea men a e i on(III) sul a e, aluminum sul a e, aluminum chlo ide, i on(III) chlo ide, as well as i anium disul ide and zi conyl chlo ide oc ahyd a e [11]. 2.1.1. P e-hyd olyzed me al coagulan s To minimize he disad an ages o ino ganic coagulan s, hey may be hyd olyzed, c ea ing an ino ganic polyme wi h imp o ed coagula ion p ope ies. Bu gene ally, we could say ha hey a e much mo e e ec i e han he monome s o sal s om which hey a e p oduced. Among hei mos equen ly men ioned bene i is a highe e ec i eness a lowe dosage. Because a smalle amoun o he coagulan is used du ing he wa e ea men , a a lowe olume o sludge is p oduced [12], no do hey lea e as many esidual ca ions in he ea ed wa e . Unlike hei monome s, hey unc ion wi hin la ge anges o pH and a e less sensi i e o empe a u e [21]. These g oups o coagulan s include he equen ly used polyaluminium chlo ide (PAC), as well as polyme s o i on(III) sul a e, polyaluminium silica e-chlo ide and polyaluminium silica e sul a e. 3. O ganic polyme s as coagula ion agen s Na u al o syn he ic mac omolecula wa e -soluble subs ances a e p ima ily used as des abilizing o auxilia y agg ega ion agen s ( locculan s). The use o polyme s enables as e loccule sedimen a ion ( he o ma ion o loccules wi h s onge , dense s uc u e) and imp o ed il e abili y o he o med suspension. Fu he , polyme locculan s dec ease he con en o o ganic subs ances, including u bidi y as well as esidual coagulan , hus imp o ing he ul ima e quali y o he ea ed wa e . The use o hese subs ances also enables a dec ease in dosage o ino ganic coagulan s. Unlike me al coagulan s, o ganic polyme s unc ion wi hin a la ge pH ange, while ha ing no e ec on he pH o he ea ed wa e . Thei use p oduces o ma ions ha a e la ge, compac , hick and display good sedimen a ion p ope ies. Unlike me al coagulan s, o ganic polyme s lea e no me al ca ions in he ea ed wa e . High e ec i eness is achie ed e en a ela i ely small doses o he coagulan agen , educing he p oduc ion o sludge [21]. The addi ion o an app op ia e polyme o an ino ganic coagulan may signi ican ly imp o e i s e ec i eness in emo ing impu i ies, because i o ms la ge hicke loccules wi h be e sedimen a ion p ope ies [4]. O ganic polyme s a e also e ec i e in emo ing small-size pa icles. They ha e a double e ec on coagula ion – aside om cha ge neu aliza ion, hey also ha e a b idging e ec [7]. B idging is speci ically mos no able in long molecules wi h la ge molecula weigh . Du ing he eac ion, he polyme is bound o he pollu ing pa icle in se e al places and he loops o loose ends o he polyme loa in space, eady o bind o ano he pa icle. Among o he ac o s, he e ec i eness o coagula ion is de e mined by he dosage o he agen . Should he dose be oo low, a ce ain a io o impu i ies emain 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 3 in he wa e . To he con a y, should he dose be oo high, he pollu an s a e dispe sed again and he polyme s subsequen ly plug he il e s [3]. O ganic polyme s a e cu en ly used p ima ily as auxilia y coagula ion and loccula ion agen s [15], al hough hey may also be used as p ima y coagulan s. Wide use o o ganic polyme s is p e en ed by hei highe cos . Cu en ly, hey a e also a cen e o ocus ega ding possible heal h isks [30]. O ganic polyme s may p ima ily be di ided in o ei he syn he ic o na u al. Depending upon hei o e all cha ge hey u he di ide in o ca ion, anion, and cha ge neu al. Syn he ic o ganic polyme s (such as ca ion polyac ylamides) a e usually e y e icien coagulan s, bu unlike na u al polyme s, hey end o be mo e cos ly, a e no biodeg adable and show ce ain dange ous p ope ies ( oxici y, ca cinogenic p ope ies). Na u al o ganic polyme s a e somewha less e ec i e, bu a e biodeg adable, no oxic and do no p oduce any seconda y pollu ion [21]. 4. Na u al polyme s O e ime, he e has been an e o o eplace classic coagulan s wi h na u al non- oxic and en i onmen ally- iendly subs ances. The eason may be he high cos o limi ed a ailabili y o commonly used coagulan s (aluminum sul a e, i on(III) sul a e, syn he ic polyme s e c.), he equi emen o highly e ec i e doses o hese agen s, p oduc ion o an no able olume o sludge [12] and he undesi able oxici y o he esidual coagulan s ha emain in he ea ed wa e . The use o seeds o ce ain plan s ( o example Lens esculen a, Tama indus indica, Cyamoppsis pso aloides) p esen s a cos -e ec i e, p ac ical and sui able solu ion o wa e ea men in de eloping coun ies and beyond. A ce ain p epa a ion is necessa y in o de o use hese seeds, including d ying, g inding and dilu ion wi h wa e . 4.1. Ca ion polyelec oly es S ong ca ion polyelec oly es ha e a posi i e cha ge ega dless o he pH o he solu ion. To he con a y, weak ca ion polyelec oly es ha e a posi i e cha ge only in an acidic en i onmen , as co e ed [4]. Na u al coagulan s we e used long be o e chemical sal s. Bu in he end hey we e pushed o he backg ound, as he use o sal s appea ed o be an easie and be e solu ion o ea ing d inking wa e . In his ega d, wi h he inc easing necessi y o ea wa e in de eloping coun ies, na u al polyme s a e e u ning o he cen e o a en ion [23]. Na u al polyme s a e easily a ailable, cos -e ec i e and easy o handle. Among he common na u al ca ion polyme s a e he polysaccha ides. The main ad an age o polysaccha ides is ha hey a e biodeg adable, al hough hey a e he leas e ec i e and mus be used in high concen a ions. A combina ion o syn he ic polyme s on o polysaccha ides o ms a b anched polyme wi h imp o ed e ec i eness [4]. The mos equen ly used na u al ca ion polyme is chi osan. Chi osan is no wa e -soluble and mus he e o e be dissol ed in a solu ion o a ca boxylic acid, such as ace ic acid [22]. Among o he na u al ca ion polyme s a e bo h s a ch and annins [23]. Tannins include many seconda y me aboli es o plan o igins. They a e ound in ba k, lea es o seeds o plan s. A e y p omising ca ion polyme among he annins is an ex ac ob ained om he seeds o he Mo inga olei e a ee, con aining a ca ion p o ein. The main ad an age o his ex ac is ha i is no oxic o ei he humans o animals, while se ing as a a he e ec i e coagulan . Fu he , i does no cause p oblems wi h co osion and p oduces less sludge. Compa ed wi h aluminum o i on sal , he ex ac shows a lesse e ec in emo ing u bidi y. T ea men o wa e wi h his ex ac inc eases he con en o o ganic subs ances (pa icula ly o hophospha es and ni a es) in he ea ed wa e . These esidue subs ances may wo sen he o ganolep ic p ope ies o wa e , such as colo , as e and odo [4, 16, 19]. O he op ions o wa e ea men use ex ac s om he seeds o he Eu opean ho se-ches nu (Aesculus hippocas anum), English oak (Que cus obu ), Aus alian oak (Que cus ce is), No he n ed oak (Que cus ub a) and swee ches nu (Cas anea sa i a). The concen a ion o he ob ained ca ion p o eins a e app oxima ely en- imes less han in he case o Mo inga olei e a, ye , despi e his, good coagula ion p ope ies we e con i med [5, 24]. 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 4 O ganic ca ion polyme s may be used bo h as auxilia y coagula ion- loccula ion agen s and as p ima y coagulan s. Coagula ion p ope ies o ca ion polyme s used as p ima y coagulan s may addi ionally be imp o ed by he addi ion o insoluble solid subs ances such as clay o me al oxides (i on, aluminum and manganese oxides). Fo example, chi osan alone has a low e iciency in emo ing u bidi y and colo , bu when mixed wi h ben oni e, i s e ec i eness imp o es syne gically. Solid pa icles unc ion as so ben s o NOM and, simul aneously, as a co e o condensing a NOM-polyme complex. 4.1.1. Mo inga olei e a ee seeds Mo inga olei e a is an oil-p oducing ee o iginally om No he n India (Himalayas), cu en ly sp ead ac oss opical egions wo ldwide. The plan is no able o i s high esis ance o d ough . Mo inga seeds a e composed o app oxima ely 31% p o ein, 18% saccha ides and 37% a s. Powde om g ound seeds con ains soluble p o eins capable o loccula ing u bidi y con ained in wa e . The solubili y o hese p o eins is inc eased wi h he con en o sal s in wa e . Sodium chlo ide (NaCl) is hus some imes used du ing labo a o y p epa a ions o he coagula ion agen . The coagula ion e ec o he ex ac p epa ed wi h he use o sal shows g ea e e ec i eness han agen s p epa ed using only ap o dis illed wa e . S udies p o e ha , in he case o Mo inga olei e a, adso p ion, cha ge neu aliza ion and o ma ion o polyme b idges be ween pa icles a e he p edominan mechanisms o emo ing u bidi y [13, 26]. The p ocesses o p epa ing a coagula ion agen om Mo inga olei e a seeds may di e . None heless, he polyelec oly e used o wa e ea men is in mos cases ob ained by g inding d ied seeds om he ee and mixing hem wi h wa e . The p o eins wi h p edominan ly posi i e cha ge on hei su ace a e hus ans e ed in o he wa e solu ion. A ypical dose o p epa a ion anges om 10 o 50 g ams o g ound seeds pe li e o wa e . The suspension o seeds wi h wa e is shaken in ensi ely o allow he de elopmen o molecules, ollowed by il a ion. The dosage o coagula ion agen anges om 75-200 mg·l-1 depending on he p ope ies (pa icula ly u bidi y) o ea ed wa e [16]. In case cooling o he suspension is possible, i s e ec is ex ended by up o one week. O he wise i is necessa y o p epa e a esh suspension daily. The e ec o Mo inga olei e a ex ac in emo ing u bidi y om wa e dec eases by ex ending he s o age pe iod o he p epa ed coagula ion agen [26]. 4.1.2. Chi osan Chi osan is a subs ance insoluble in mos o ganic sol en s. Howe e , i dissol es in bo h o ganic and ino ganic acids (such as ace ic acid, o mic acid, e c.). This polysaccha ide is p oduced h ough an alkaline deace yla ion o chi in, which is ound in he ou e shells o c us aceans, insec s and gas opods, as well as wi hin he cellula walls o yeas and ce ain ungi. Chi in and chi osan may be p oduced om he was e p oduc s o p ocessing ma ine animals [28]. Chi osan p oduced o he pu poses o wa e ea men is ypically p epa ed using ace ic acid whe e i is a subjec o hyd olysis. Chi osan is a ca ion polyelec oly e used o he educ ion o wa e u bidi y [20], so p ion o me al i ons, as well as emo al o o ganic pollu ion. Des abiliza ion p ima ily akes place h ough he mechanism o cha ge neu aliza ion. Chi osan is a biodeg adable subs ance and i s use in wa e ea men is he e o e mo e en i onmen ally iendly han commonly used coagulan s. The equen use o chi osan is inc easing in ecen yea s. This subs ance is used o example in No way, whe e i was selec ed as a coagulan in se e al wa e ea men acili ies, used ei he exclusi ely o in a combina ion wi h me al- based coagulan s [20]. Chi osan has many ad an ages in compa ison wi h adi ional coagulan s ( locculan s). Among hem a e e ec i eness in low doses, success in he educ ion o chemical oxygen demand (COD), he abili y o emo e me al ions, he o ma ion o la ge ( oluminous) loccules wi h highe sedimen a ion a es, biological deg adabili y, majo e ec in he emo al o algae and suspended pa icles, an i-bac e ial e ec s and ze o o ma ion o seconda y pollu ion [1]. Chi osan is capable o binding bo h a s and me als, including a senic, molybdenum, cadmium, ch omium, lead and cobal [14]. Many s udies ha e been conduc ed ega ding he use o chi osan as a single coagulan o in combina ion wi h o he agen s in emo ing u bidi y [2, 20]. 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 5 Chi osan, as a posi i ely cha ged polyme wi h long chains, is able o coagula e nega i ely cha ged and inely dispe sed colloidal pa icles h ough adso p ion, cha ge neu aliza ion, hyd ophobic e ec o h ough he o ma ion o polyme b idges. Conside able sa ings in e ms o he olume o agen s used may be achie ed by using such na u al coagulan s in combina ion wi h he mo e classic o ms, esul ing in addi ional cos educ ions o sludge emo al, as i is p oduced in smalle quan i ies [1]. A coagula ion ja es was [20] pe o med using aw wa e om he E ans Lake in Cali o nia, compa ing he e ec s o chi osan, aluminum sul a e and i on(III) chlo ide. Upon pe o ming he coagula ion, sedimen a ion and il a ion using il a ion pape , he esul ing alues o u bidi y educ ion we e 98.8% (aluminum sul a e), 96.9% (chi osan) and 98.9% (i on(III) chlo ide). The emo al o coli o m bac e ia was mos e ec i e wi h i on(III) chlo ide and leas e ec i e using chi osan (upon op imal doses o coagulan s and pH alues). Chi osan was he mos e ec i e o all agen s used in emo ing colo and also caused only mino wa e so ening (by 22 %). In he case o chi osan, excessi e doses caused e-s abiliza ion o he dispe sion. Op imum pH mus be kep in mind when ea ing aw wa e in o d inking wa e . 5. Me hods Ou labo a o y esea ch ocused on es ablishing he e ec o selec ed na u al polyme coagulan s o igina ing om he seeds o he Mo inga olei e a ee and chi osan. The e ec i eness o bo h hese agen s was compa ed o a con en ional coagulan – aluminum sul a e (50% solu ion). 5.1. Raw wa e Raw su ace wa e sampled om he S a ka Ri e was used in he labo a o y es . The esea ch used a olume o app oxima ely 30 li e s. A he ime o es ing, he aw wa e had a empe a u e o 18.2° C, u bidi y 8.92 (NTU) and a pH alue o 7.85. The pH alue was adjus ed using sul u ic acid o a alue o 7.5. This alue was s ipula ed wi h ega d o p e ious es s wi h aluminum sul a e. Ou esea ch was pe o med wi h a s anda d ja es using a blending column wi h a paddle blende . Tu bidi y was used as he indica o o e ec i eness. Aside om u bidi y, he pa ame e s o wa e empe a u e and pH we e also moni o ed. P ocess pa ame e s we e iden ically main ained o all h ee agen s wi h he pa icula goal o e i ying whe he o he condi ions o an ac ual applica ion p ocess would equi e adjus men upon changing he coagulan . Fas blending was i s pe o med o a du a ion o 2 minu es a he a e o 150 pm, ollowed by slow blending a 40 pm o 20 minu es. Subsequen ly, a 60-minu e undis u bed sedimen a ion comple ed he p ocess. 5.2. Mo inga olei e a seeds A coagulan was ob ained by p ocessing 9 pieces o Mo inga olei e a seeds and used in a se ies o es s. The whi e ounded co es unde he peel we e pul e ized in a mo a and pes le o powde o m. The amoun ob ained was ans e ed o a po celain bowl and weighed. The weigh o he agen amoun ed o 1.262 g. A coagulan was p epa ed by mixing he powde om he seeds wi h 306 ml o d inking wa e ( he addi ional 6 ml we e added due o loss o wa e in he subsequen il a ion by being abso bed by he clo h). The suspension was in ensi ely shaken o he du a ion o 5 minu es and subsequen ly il e ed h ough a clean co on clo h o sepa a e la ge pa icles. A dose anging om 2.5 o 42.5 ml o he solu ion was added o he indi idual essels, ep esen ing 20.6 o 350.9 mg o powde . 5.3. Chi osan The e ec o chi osan in emo ing u bidi y was examined las . The agen was used in he o m o 25 g o whi e powde – chi osan o igina ing om sh imp shells. Chi osan was dissol ed in ace ic acid (99%), ha was subsequen ly mixed wi h 32.6 ml o d inking wa e and used in he o m o a solu ion a he concen a ion CH3COOH 1 mol·dm-3. Subsequen ly, 0.1 g o chi osan was added o he acid solu ion. This o med a liquid o a a he hick consis ency ha was u he dilu ed wi h d inking wa e o a 100 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 6 ml olume. This coagulan (100 mg o chi osan in 100 ml o he agen ) was dosed o he essels in an op imiza ion ja es . 6. Resul s Ou esea ch ocused on he compa ison o e ec i eness in educing u bidi y a e applying h ee coagulan s used in wa e ea men . The selec ed coagulan s we e aluminum sul a e commonly used as a con en ional coagulan , as well as chi osan and Mo inga olei e a as al e na i es. An op imiza ion ja es was pe o med wi h he es ed aspec being u bidi y. The esea ch was ca ied ou in he labo a o y o ma as a se ies o ja es s. 6.1. Aluminum sul a e Aluminum sul a e was selec ed as ep esen a i e o con en ional agen s used in wa e ea men . The pu pose o i s use in his esea ch s udy is p ima ily as a compa ison wi h he o he wo agen s ha a e no as equen ly used and p ac ically ne e in he Czech Republic. The au ho s o his a icle ha e ex ensi e p e ious expe ience wi h his coagulan in ela ion o aw wa e used in his esea ch. As is appa en om p e ious ja es s, he op imum pH o u bidi y emo al is 7.5, he a e o he i s phase o mixing is 150 pm ( o he du a ion o 2 minu es) and he a e o he second phase o coagula ion is 40 pm ( o 20 minu es). The same alues we e also used o he compa ison es s wi h he o he agen s. The esul s a e appa en om Table 1 and Figu e 1. Table 1. Tu bidi y emo al – aluminum sul a e Sample Dosage Tu bidi y Tu bidi y emo al Aluminum sul a e Al @ 60 min [ml] [mg] [mg] [NTU] [%] 1 0.050 65.5 2.6 3.56 60.09 2 0.075 98.3 3.9 2.13 76.12 3 0.100 131.0 5.2 0.94 89.46 4 0.115 150.7 6.0 0.46 94.84 5 0.130 170.3 6.8 0.65 92.71 6 0.175 229.3 9.2 0.85 90.47 7 0.220 288.2 11.5 1.00 88.79 8 0.265 347.2 13.9 1.26 85.87 The lowes measu ed alue o u bidi y a e six y minu es o sedimen a ion was 0.46 NTU in case o 0.115 ml dose o aluminum sul a e. The dec ease o NTU by 8.46 shows emo al o u bidi y a 94.84 %. The wo s esul was eco ded a doses o 0.050 ml – he alue o he u bidi y 3.56 ZF and u bidi y emo al a only 60.09 %. 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 7 Figu e 1. Tu bidi y emo al – aluminum sul a e A la ge numbe o disce nable loccules o med when using aluminum sul a e, e en in he ea ly s age o as blending. The mos agg ega es we e o med in he wa e o which mos o he agen was dosed. Upon 60 minu es o sedimen a ion he loccules se led a he bo om, whe e hey o med sludge o a ligh b own colo . The op imal dose o aluminum sul a e 150.7 mg·l-1 managed o educe he u bidi y by 94.84 % o a alue o 0.46 NTU. 6.2. Mo inga olei e a The coagulan ob ained om Mo inga olei e a seeds by he me hod desc ibed abo e was used o ea wa e o iden ical quali y as abo e and also wi hin a labo a o y-scale es . The same pa ame e s we e se o he coagula ion es . The o ma ion o small ligh -colo ed loccules in he ea ed wa e was eco ded as ea ly as he slow blending s age. The amoun o hese small obse ed clus e s g ew wi h inc eased amoun s o he coagula ion agen . Howe e , he loccules emained suspended in he olume o he essels h oughou he en i e phase and we e only pa ly sedimen ed. Only a po ion o he loccules se led on he bo om, along wi h sedimen . Despi e his, lowe le els o u bidi y we e measu ed han p io o wa e ea men . Resul s a e shown in Figu e 2. 5 h In e na ional Con e ence on New Ad ances in Ci il Enginee ing (ICNACE 2019) IOP Con . Se ies: Ma e ials Science and Enginee ing 800 (2020) 012032 IOP Publishing doi:10.1088/1757-899X/800/1/012032 8 Figu e 2. Tu bidi y emo al – Mo inga olei e a As is appa en om he abo e esul s, he mos e ec i e dose o Mo inga olei e a o u bidi y emo al was 164.6 mg. The ini ial u bidi y alue was educed o 1.60 NTU, ep esen ing he emo al o 82.04% o u bidi y. The lowes alue o u bidi y emo al was measu ed a he dose o 20.6 mg o Mo inga olei e a. He e, he u bidi y alue only dec eased by 0.01 NTU. When using Mo inga olei e a, he loccules o med du ing coagula ion we e o pale colo . They we e isible o he naked eye only in he second phase o blending. The sedimen a ion o he agg ega es ook place e y slowly. E en a e one hou o sedimen a ion, he e we e no appa en changes. The op imum dose was 164.6 mg·l-1, which is he la ges in compa ison wi h bo h aluminum sul a e and chi osan. Be e esul s o u bidi y emo al could appa en ly be achie ed by p olonging he sedimen a ion pe iod o using il a ion. 6.3. Chi osan The nex coagula ion es s we e using chi osan as an agen – also unde he same condi ions. The o ma ion o loccules in aw wa e was isible om app oxima ely he middle o he slow blending phase. The smallagg ega es had a ligh b own colo and se led mo e quickly han he agg ega es using Mo inga olei e a. Al hough mos loccules se led a e 60 minu es o sedimen a ion, a po ion o he loccules emained suspended. As ega ds u bidi y emo al, he esul ing alues a e shown in Figu e 3.