Conditioning and dewatering of anaerobically digested sludge from municipal wastewater treatment processes

This thesis presented the dewatering performance improvement of anaerobically digested sludge with novel application and assessment of conditioning aids. The effectiveness of sludge conditioning was evaluated by batch experiments using a series of 250-mL jar test beakers. The optimal dosage was found at 15–20 g/kg chitosan with enhanced dewaterability and rheological behaviour. The dual-chemical conditioning results indicate a higher rate of water removal at the expense of dry solids content compared to single conditioning

Dual-conditioning of Sludge using Chitosan and Metal Cations

Sludge dewatering is important in sludge management and disposal. In practice, chemical conditioners are often introduced to aid sludge dewatering. This study investigated the simultaneous application of chitosan and metal cations as dual-conditioners to improve sludge dewaterability. The dewatering performance of sludge was evaluated using three common measurements, i.e. capillary suction time, specific resistance to filtration, and moisture content of the filtered sludge cake. The effectiveness of metal cations in sludge conditioning and dewatering was found, in ascending order, to be Na+ < K+ ≈ Mg2+ < Ca2+ < Al3+ < Fe3+. Dual-conditioning using chitosan and metal cations further enhanced dewaterability. Cations may have significant effects on sludge conditioning by neutralization of negative surface charges, bridging of floc components, and the salting out effect, leading to improved dewaterability when used in conjunction with chitosan

Effect of Ethrel as a Flower Induction Agent on the Growth and Quality of Fresh Golden Pineapple (MD2) in Malaysia

Ethrel was proposed as a good flowering agent to induce the flowering of various fresh pineapples. However, very limited research studies have been carried out on the effect of this inducing agent on the growth of the golden pineapple or Millie Dillard (MD2) in Malaysia, with none in Sarawak. To address this research gap, this study aims to investigate the effect of ethrel on the growth and fruit quality of MD2 pineapples growth in Miri, Sarawak. In this study, ethrel acts as an induction agent that was applied to induce the pineapples at maturity around 11 months after planting (MAP). Moreover, these induced pineapples were harvested 15 MAPs, whereas no pineapples were available for harvesting from the control group that was induced by natural flowering. These results showed that ethrel provided a higher yield in the number of pineapples compared to natural flowering, classifying them as Grade B pineapples. For the growth and fruit quality of the MD2 pineapples, it was found that the average values for the total soluble solids (TSS), total titratable acidity (TTA), pH, diameter, height with a crown, and whole fruit fresh weights with the crown of the pineapples were 16.48 Brix, 0.54 %, pH 3.89, 11.7 cm, 40.3 cm, and 1.4 kg, respectively. Furthermore, the average TSS to TTA ratio was 32.52, which was within the range of 5.5 to 66.4, indicating that the pineapples were sweet with prospects for commercial selling. Hence, it can be concluded that using ethrel as an induction agent is significant in Malaysia

Teaching Engineering Ethics using BLOCKS Game

The aim of this study was to investigate the use of a newly developed design game called BLOCKS to stimulate awareness of ethical responsibilities amongst engineering students. The design game was played by seventeen teams of chemical engineering students, with each team having to arrange pieces of colored paper to produce two letters each. Before the end of the game, additional constraints were introduced to the teams such that they faced similar ambiguity in the technical facts that the engineers involved in the Challenger disaster had faced prior to the space shuttle launch. At this stage, the teams had to decide whether to continue with their original design or to develop alternative solutions. After the teams had made their decisions, a video of the Challenger explosion was shown followed by a post-game discussion. The students’ opinion on five Statements on ethics was tracked via a Five-Item Likert survey which was administered three times, before and after the ethical scenario was introduced, and after the video and post-game discussion. The results from this study indicated that the combination of the game and the real-life incident from the video had generally strengthened the students’ opinions of the Statements

Reverse micelle extraction of antibiotics

Many biomolecules such as proteins, enzymes and metal ions could be solubilised effectively into the reverse micelle organic solvents. Therefore, this opens the possibility of using the existing liquid-liquid extraction technology and utilizing reverse micelles for large-scale extraction in downstream processing. So far, there has been very limited research on the use of reverse micelle for antibiotics extraction. Thus, an attempt was made to use dioleylphosphoric acid (DOLPA) reverse micelle to extract antibiotics. It was found that pH, surfactant concentration, as well as antibiotic types and concentration have a significant effect on the solubilizing capacity of antibiotics in the DOLPA reverse micelles system. At optimum conditions, about 63 % of penicillin G could be extracted during forward extraction, and 54 % in backward extraction

Dewatering of Anaerobic Digested Sludge with Oil Palm Biomass as Novel Physical Conditioner

This study investigated the use of oil palm biomass, namely empty fruit bunch (EFB), palm kernel shell (PKS), and the biomass residue, palm ash (PA), as physical conditioner, to improve the dewaterability of anaerobic digested sludge. The dewatering performance of the conditioned sludge in this work was evaluated with four common measurements i.e. the capillary suction time (CST), specific resistance to filtration (SRF), net sludge solids yield (YN), and moisture content of the sludge cake. Amongst all the biomass samples, the ground EFB passing through a 0.6-mm mesh sieve indicated the highest reduction in SRF and the highest gain in YN at solids mass ratio of conditioner to sludge of 1.6. When the conditioned sludge was subjected to filtration dewatering, the presence of oil palm biomass in sludge may act as a skeleton builder to provide a porous, permeable and rigid lattice sludge cake structure which allows the passage of water and consequently enhances water removal from sludge

Assessment of Chitosan Conditioning in a Synthetic Anaerobic Digested Sludge System

Effects of dosage and pH in chitosan conditioning were investigated for studying the anaerobic digested sludge dewatering characteristics using a modified synthetic sludge system. A comparison was made with the conditioning results using inorganic metal cations. Capillary suction time, turbidity and filtered cake solids content were measured to assess sludge dewaterability. Floc sizes and the Fourier Transform Infrared spectrums were also examined for the conditioned sludge properties. Experimental results indicate that sludge conditioned with chitosan showed remarkable dewaterability with close resemblance to real sludge system. A strong correlation between floc size and dewaterability was observed with increasing chitosan dosage. The optimum dewaterability was found in the acidic region. The synthetic sludge conditioned with chitosan showed comparable dewaterability with the one conditioned with trivalent cation. This proposed synthetic sludge behaves similar to a typical anaerobic digested sludge when conditioned with chitosan