Microbial Community Shift and Role of Bacteria in Rapid Granulation By Using Diatomite

Aerobic granular sludge (AGS) technology is a promising biological method for modern wastewater treatment. However, granulation time have become a major issue for the application of AGS technology especially in low strength wastewater. Recent studies on granulation are focusing towards rapid start-up granulation process. Diatomite, a friable light-coloured sedimentary rock was introduces in this study to enhanced the granules formation. This study highlight the effect of diatomite towards the microbial community during the transformation of seed sludge until development of granules. DNA extraction and Metagenomic analysis was conducted with three samples (seed sludge, control AGS, AGS diatomite) to compare the microbial community. The microbial community analysis revealed the alpha diversity, phylum and class level, and the abundance of EPS producing bacteria of each bacteria samples respectively. Diatomite has a significant influence towards the microbial diversity (High Shannon index alpha diversity). Also, diatomite promotes the abundance of functional bacteria especially EPS producing bacteria, which seen as a crucial elements in granulation process.

Analysis of Biogas Production from Biomass Residue of Palm Oil Mills using an Anaerobic Batch Test

The Malaysian palm oil industry has grown rapidly due to Malaysia’s tropical weather and suitable terrain. Palm oil production is now categorized as the most significant agriculture-based industry in the country. Along with strong economic returns, the palm oil industry also generates an abundance of waste products, including empty fruit bunches (EFB) (23%), mesocarp fibre (12%), shells (5%) and palm oil mill effluent (POME) (60%) for every batch of fresh fruit bunches (FFB) processed in the mills. This study is meant to fill the gap from previous studies in terms of biogas productions from the POME or the combination of POME and EFB which normally been conducted under the thermophilic conditions. The appropriate mixture ratios between POME and EFB in anaerobic digestion will reduce time of treatment and space if been conducted in the low temperature (mesophilic conditions). Thus, this paper is focuses on the analysis of batch test design which consist of low temperature (mesophilic, 20-40 °C) conditions for evaluating the performance of biogas production from the combination of POME and EFB in anaerobic digestion. The aim was to determine the amount of biogas production based on different ratios of POME and EFB mixtures. Biogas 1, containing 160 mL of fresh POME mixed with 40 g of EFB, was shredded and blended with 1800 mL seed sludge. Biogas 2, containing 120 mL of fresh POME mixed with 80 g of EFB, was shredded and blended with 1800 mL seed sludge. Based on the analysis of the results, the total production of Biogas 1 was greater than that of Biogas 2. The findings also show that the ratio of POME and 20% EFB (Biogas 1) was more efficient in producing the biogas compared to the ratio POME and 40% EFB (Biogas 2) under the mesophilic conditions. Thus, the mesophilic conditions required energy saving and low-cost process, compared to the previous studies which used the high temperature (thermophilic, 41-122 °C) that definitely was costly and require more energy consumption. This study will serve as preliminary results for enhancing the treatment methods use in Malaysia and form the early basis for the development of a new technology incorporating a combination of POME and EFB.

Enhancement of Bioreactor Performance Using Acclimatised Seed Sludge in Anaerobic Treatment of Chicken Slaughterhouse Wastewater: Laboratory Achievement, Energy Recovery, and Its Commercial-Scale Potential

Lack of good management practice of chicken slaughterhouse wastewater (CSWW) has caused pollution into water bodies. In this study, the potential of seed sludge acclimatised modified synthetic wastewater (MSWW) on bioreactor performance and energy recovery of CSWW treatment was investigated. Two sets of upflow anaerobic sludge blanket (UASB) reactors were employed. The seed sludge in UASB 2 was acclimatised with MSWW for 30 days. In UASB 1, no acclimatisation process was undertaken on seed sludge for control purposes. After the acclimatisation process of UASB 2, both reactors were supplied with CSWW under the same condition of organic loading rate (OLR = 0.5 to 6 gCOD/L/d) and mesophilic condition (37 °C). COD removal efficiencies of UASB 2 were >80% all through the steady-state of the OLR applied. Meanwhile, a drastic decrease in overall performance was observed in UASB 1 when the OLR was increased to 3, 4, 5, and 6 gCOD/L/d. Energy recovery from laboratory scale and projected value from commercial-scale bioreactor were 0.056 kWh and 790.49 kWh per day, respectively. Preliminary design of an on-site commercial-scale anaerobic reactor was proposed at a capacity of 60 m3.

Enhanced CH4 Production from Corn Stover by Simultaneous Lime Treatment

Calcium hydroxide (lime) treatment and solid-state anaerobic digestion (SSAD) of corn stover (CS) were carried out simultaneously with different lime doses (0, 2, 3.5, and 5%) and feedstock to seed sludge (F/S) ratios (6, 8, and 10). It was found that the addition of 3.5% lime improved CH4 yield from 118 mL/g VS to 182 mL/g VS (54% increase) during SSAD of CS when F/S ratio was at 6. The improved CH4 production is consistent with increased relative abundance of several microbes that might play important roles in biomass degradation and CH4 generation. At higher F/S ratios (8 and 10), SSADs with different lime doses (0–5%) were all upset with accumulation of volatile fatty acids. Addition of 3.5% lime can obtain a net benefit of $18.4/tonne TS which are 44% of the gross benefit of power production ($41.5/tonne TS) via SSAD of CS and combined heat and power system.

Powdered Ceramsite and Powdered Limestone Use in Aerobic Granular Sludge Technology

The effects of two powdered mineral materials (powdered ceramsite and powdered limestone) on aerobic granulation of sludge were evaluated. The experiment was conducted on a laboratory scale bioreactors treating wastewater for 89 days. Three granular sequencing batch reactors (GSBRs) were operated at the lowest optimal organic loading rate (OLR) of 2.55 g COD/(L∙d). In the control reactor (R1), the mean diameter (d) of the biomass ranged from 124.0 to 210.0 µm, and complete granulation was not achieved. However, complete granulation did occur in reactors to which either ceramsite (251.9 µm < d < 783.1 µm) or limestone (246.0 µm < d < 518.9 µm) was added. Both powdered materials served as a ballast for the sludge flocs making up the seed sludge. Ceramsite particles also acted as microcarriers of granule-forming biomass. The granules in the reactors with added powdered materials had nonfibrous and smoother surfaces. The reactor with ceramsite exhibited the highest average efficiencies for COD, total nitrogen, and total phosphorus removal (85.4 ± 5.4%, 56.6 ± 10.2%, and 56.8 ± 9.9%, respectively). By contrast, the average nitrification efficiency was 95.1 ± 12.8%.