220
A. Z. Yaser and N. N. Safie
Multimedium filtration has been done by Deshmukh et al. (2017) by using three
layers that comprised of activated charcoal (~75 µ), sand (1–1.36 mm) and aggregate (10–12.5 mm). The activated charcoal functions to increase the surface area for
removal of contaminants and aggregate or filter gravel has been used as a support
media to sand filter that has slower break down. This method can remove about
85%–90% and 60%–70% COD and BOD removal, respectively. During the experimental study, it is observed that for finer particles, efficiency of filter is high and for
larger size particles, efficiency of filter is less.
3.1.2 Chemical Treatment
Coagulation–Flocculation
Coagulation–flocculation process is regarded as one of the most important and widely
used treatment processes of industrial wastewaters due to its simplicity and effectiveness (Teh et al. 2016). Hydrolyzing Al (III) salts and Fe (III) salts are the most
common metal coagulants used in the coagulation/flocculation process (Teh et al.
2016). This is due to the availability of strong trivalent electrolytes which is excellent
in coagulation process. These metal coagulants are known to produce acidic effect
on the treated wastewater in which neutralization is needed prior to discharge to the
water bodies (Tamrin and Zahrim 2017). This has led to the usage of other types of
coagulants such as organic polymer and synthetic polymer. Organic polymers are
typically classified as long-chain organic molecules with molecular weights varying from 10
4 to 10
6 and it can be cationic (positively charged), anionic (negatively
charged) or nonionic (no charge) (Metcalf and Eddy 2003).
Coagulation–flocculation method has been used to treat campus sewage of Universidad Autonoma Metropolitana-Unidad Azcapotzalco (UAM-A) in Mexico City
which originated from sources such as laboratories, toilets, kitchens, and general
services (Torres et al. 2015). This study investigated the usage of metal and polymer
coagulants such as ferric chloride, guar gum, HPTAC-guar, LBG Prosopislaevigata,
and Annonamuricata. Highest COD removals were assessed using Annonamuricata
seed gum (66.05%), and ferric chloride (65.81%). Regarding the turbidity removal,
the best results were achieved for ferric chloride (54.08%) and guar gum (45.92%).
Significant variations in sludge generation were observed. The largest amount of
sludge was obtained using ferric chloride (26 mL/L), followed by Annona muricata
seed gum (10 mL/L). Higher rate of COD and turbidity removal was recorded at the
highest polymer coagulant concentration being used.
Commercial synthetic polymer based coagulants and metal coagulants reported
to cause fouling effect or cloth blinding on surface of membrane during nanofiltration process due to the formation of sticky or gelatinous cake layer that block the
mechanical pore of the filter (Genter et al. 2018). According to Liu et al. (2012),
the performance of coagulation is effective when metal salts is used in low dosage
of coagulants. According to Zahrim et al. (2017), employing dual coagulants can
also improve the coagulation rates. Zahrim et al. (2010) stated that best polymer
A. Z. Yaser and N. N. Safie
Multimedium filtration has been done by Deshmukh et al. (2017) by using three
layers that comprised of activated charcoal (~75 µ), sand (1–1.36 mm) and aggregate (10–12.5 mm). The activated charcoal functions to increase the surface area for
removal of contaminants and aggregate or filter gravel has been used as a support
media to sand filter that has slower break down. This method can remove about
85%–90% and 60%–70% COD and BOD removal, respectively. During the experimental study, it is observed that for finer particles, efficiency of filter is high and for
larger size particles, efficiency of filter is less.
3.1.2 Chemical Treatment
Coagulation–Flocculation
Coagulation–flocculation process is regarded as one of the most important and widely
used treatment processes of industrial wastewaters due to its simplicity and effectiveness (Teh et al. 2016). Hydrolyzing Al (III) salts and Fe (III) salts are the most
common metal coagulants used in the coagulation/flocculation process (Teh et al.
2016). This is due to the availability of strong trivalent electrolytes which is excellent
in coagulation process. These metal coagulants are known to produce acidic effect
on the treated wastewater in which neutralization is needed prior to discharge to the
water bodies (Tamrin and Zahrim 2017). This has led to the usage of other types of
coagulants such as organic polymer and synthetic polymer. Organic polymers are
typically classified as long-chain organic molecules with molecular weights varying from 10
4 to 10
6 and it can be cationic (positively charged), anionic (negatively
charged) or nonionic (no charge) (Metcalf and Eddy 2003).
Coagulation–flocculation method has been used to treat campus sewage of Universidad Autonoma Metropolitana-Unidad Azcapotzalco (UAM-A) in Mexico City
which originated from sources such as laboratories, toilets, kitchens, and general
services (Torres et al. 2015). This study investigated the usage of metal and polymer
coagulants such as ferric chloride, guar gum, HPTAC-guar, LBG Prosopislaevigata,
and Annonamuricata. Highest COD removals were assessed using Annonamuricata
seed gum (66.05%), and ferric chloride (65.81%). Regarding the turbidity removal,
the best results were achieved for ferric chloride (54.08%) and guar gum (45.92%).
Significant variations in sludge generation were observed. The largest amount of
sludge was obtained using ferric chloride (26 mL/L), followed by Annona muricata
seed gum (10 mL/L). Higher rate of COD and turbidity removal was recorded at the
highest polymer coagulant concentration being used.
Commercial synthetic polymer based coagulants and metal coagulants reported
to cause fouling effect or cloth blinding on surface of membrane during nanofiltration process due to the formation of sticky or gelatinous cake layer that block the
mechanical pore of the filter (Genter et al. 2018). According to Liu et al. (2012),
the performance of coagulation is effective when metal salts is used in low dosage
of coagulants. According to Zahrim et al. (2017), employing dual coagulants can
also improve the coagulation rates. Zahrim et al. (2010) stated that best polymer