Anaerobic digestion is widely considered as an environmentally friendly technology for various organic waste including sewage sludge. Although the implementation of anaerobic digestion as an alternative treatment method for sewage sludge can be seen in many countries, its status in Malaysia is not clear. This study reviewed the current state of sewage sludge treatment in Malaysia and discussed the challenges to promote anaerobic digestion in sewage sludge treatment. Other than the common constraints faced, namely technical, political and economic, the characteristics of sewage sludge in Malaysia are considered to be a factor regarding feasibility. Anaerobic co-digestion is the simultaneous anaerobic digestion of two or more substrates which is a promising possible option to overcome the disadvantages of mono-digestion, and improve the economic viability due to higher methane production. There are a variety of biomasses as co-substrates in Malaysia. However, the anaerobic co-digestion of food waste and sewage sludge might be the most feasible method to overcome such constraints. Adding food waste as co-substrate is suggested as the possible approach to not only improve the process's performance but also help to handle the increasing volume of food waste in Malaysia. This study aims to highlight the potential as well as to provide a starting point for further studies regarding the treatment of sewage sludge using anaerobic digestion in Malaysia.

IJTech International Journal of Technology

Methane production characteristics of anaerobic co-digestion of pig manure (PM) and fermented liquid feed (FLF) were investigated in a continuous digester under mesophilic conditions. The experiment followed three phases. PM alone was digested in phase I. In phases II and III, PM and FLF were mixed in a ratio of 95:5 and 90:10 (% v/v), respectively. The specific methane yields (SMYs) during phases I, II, and III were 238, 278, and 326.8 mLCH₄·gVS⁻¹-added, respectively. It was due to the effect of balancing the feedstock carbon-to-nitrogen ratio by adding FLF. This improvement can also be attributed to the readily biodegradable compounds in the FLF. The higher SMY obtained in this study showed a positive synergistic effect in the anaerobic co-digestion of PM and FLF. The results also indicate that adding the FLF positively affected and maintained a constant pH level, avoiding volatile fatty acid accumulation and ammonia inhibition in the anaerobic digestion (AD). Thus, this study provides valuable information regarding the usage of unused or wasted FLF as a co-substrate for the practical AD of PM. The production of fermented liquid additives such as FLF to improve the methane production from the AD of PM is a potential novel alternative to food waste recycling in Japan, besides compost and animal feeding.

The solid phase microextraction (SPME) method was applied to drug monitoring of β-blockers in human urine and plasma. Six β-blockers (alprenolol, atenolol, oxprenolol, pindolol, β-propranolol, and timolol) were extracted from urine and plasma samples by SPME fiber coated with 85-μm polyacrylate for 2 h at 30°C. The β-blockers extracted were separated by Capcell PackTM SG120 (4.6 × 150 mm, 5 μm) with 0.05 M phospholic acid-methanol (55 + 45, v/v) and detected by photometric detection (280 nm) and fluorometric detection (excitation wavelength 220 nm, emission wavelength at 360 nm). The recoveries of β-blockers (500 μg/ml) from urine were 84.3 to 88.4%, and from plasma they were 86.4 to 90.2%. The detection limits were 2 to 25 μg/ml by the photometric detection, 0.4 μg/ml of β-propranolol by fluorescence detection. The relative standard deviations were 10.1 to 15.3% for 500 μg/ml β-blockers in urine, 9.9 to 13.2% for 5 μg/ml of β-blockers in plasma, respectively.