Treatment of Palm Oil Mill Effluent (POME) using Cassia obtusifolia Seed Gum Through Coagulation-Flocculation Process
Creators: name: Shak, Katrina Pui Yee
Publisher: name: Figshare
Year: 2016
Subjects: subject: 90403 Chemical Engineering Design
subject: FOS: Chemical engineering

description: With the economic
upsurge and continuous industrial development of Southeast Asia’s palm oil
sector, Malaysia alone produced an estimated 19 million tonnes of crude palm
oil (CPO) in 2015. However, CPO production is in tandem with the high
generations of both solid waste and effluent. Environmental issues related to
the wellbeing of watercourses became a concern due to the discharge of palm oil
mill effluent (POME). Governmental and international bodies have acknowledged
the need to develop and implement sustainable effluent management strategies,
especially concerns relating to the implementation of suitable treatment
technologies with realistic pricing. Noted for its potential to treat
organically polluted water and wastewater in major water utilities, coagulation
and flocculation treatment using natural polymers can be an ecological and
environmentally-friendly alternative to treat POME. In this study, the
feasibility of applying natural seed gum and its derivative was investigated to
treat POME by means of coagulation and flocculation processes as a sustainable
alternative to ponding systems. <br>
    <br>
   The works which were conducted in the initial stage of
research (Chapters 3 and 4) established and optimized the treatment of POME via
coagulation-flocculation process using natural Cassia obtusifolia seed gum.
Chapter 3 investigated the potential of C. obtusifolia seed gum as a natural
coagulant in comparison with aluminium sulphate (alum) in treatment of POME. A
series of batch experiments were performed under various factors: wastewater
concentration, dosage of coagulant, initial pH of wastewater, settling time,
slow stirring speed, and temperature. The removal of total suspended solids
(TSS) and chemical oxygen demand (COD) were measured and used to assess the
treatment efficiency. The findings of this study highlighted the negligible
effect of wastewater temperature on the treatment efficiency when C.
obtusifolia seed gum was used in comparison with alum. Based on the results,
the recommended conditions to treat POME (TSS: 7500 mg/L) using C. obtusifolia
seed gum were dosage, initial pH, and settling time of 1.0 g/L, pH 3, and 45
min, respectively. These treatment conditions enabled removals of TSS and COD
up to 87 and 55%, respectively. After determining the key effects of the
treatment process in Chapter 3, the influence of coagulant dosage and settling
time on TSS and COD removals were optimized via response surface methodology.
The treatment of POME using C. obtusifolia seed gum showed higher TSS (93.9%)
and COD (61.2%) removals after undergoing optimization. In addition, the
combined treatment using alum plus C. obtusifolia seed gum was examined and
optimized to explore its synergistic effect on treatment of POME at natural pH
(pH 4.8 – 5.0). The combined treatment using alum plus C. obtusifolia seed gum
yielded high TSS and COD removals up to 81.58 and 48.22%, respectively using
the following optimum conditions: alum dosage of 1.15 g/L, C. obtusifolia seed
gum dosage of 2.47 g/L, and settling time of 35.16 min. <br>
    <br>
   To further improve the potential application of C.
obtusifolia seed gum in the treatment of POME, a new derivative of the natural
seed gum was developed in the following study (Chapter 5). Since POME contains
countless colloidal particles which are negatively charged, the study was aimed
towards developing a cationic C. obtusifolia seed gum with enhanced treatment
capability. The natural seed gum was modified through an etherification process
which leads to the substitution of reactive hydroxyl groups with cationic
moieties from N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride
(CHPTAC). The influence of cationic monomer concentration, catalyst
concentration, reaction temperature, and reaction time were studied for the
synthesis based on TSS and COD removals. The study showed that cationic C.
obtusifolia seed gum, which was synthesized (at 50 °C and 5 h) using 19×10-3 mol of CHPTAC and 6×10-2 mol of sodium
hydroxide (NaOH), removed 87% of TSS and 52% of COD from the POME. C.
obtusifolia seed gum exhibited enhanced viscosity, higher magnitude of zeta
potential (+6.41 mV) and changes in composition, thermal behaviour, and surface
morphology after undergoing etherification. <br>
    <br>
   The final stage of this research (Chapter 6) optimized the
treatment of POME using cationic C. obtusifolia seed gum. In addition, an
integrated approach was investigated by employing ultrasonic technology to
further assist coagulation-flocculation treatment of POME. The first stage of
optimized coagulation-flocculation treatment required 0.4 g/L of cationic seed
gum and 48 min of settling time. The performance of a subsequent
coagulation-flocculation treatment using 0.22 g/L of cationic seed gum and 49
min of settling time was enhanced by the introduction of an ultrasound
treatment lasting for 47 min at intensity of 49% prior to the subsequent
treatment. Ultrasonic irradiation was found to improve subsequent
coagulation-flocculation treatment by 27 and 3% in TSS and COD removals in
comparison with unassisted and continuous coagulation-flocculation treatment.
The overall study demonstrated the simple and effective use of modified natural
polymers and ultrasonic-assisted coagulation-flocculation treatment systems to
facilitate solid-liquid separation of POME.