Planning hydrological restoration of peatlands in Indonesia to mitigate carbon dioxide emissions

Extensive degradation of Indonesian peatlands by deforestation, drainage and recurrent fires causes release of huge amounts of peat soil carbon to the atmosphere. Construction of drainage canals is associated with conversion to other land uses, especially plantations of oil palm and pulpwood trees, and with widespread illegal logging to facilitate timber transport. A lowering of the groundwater level leads to an increase in oxidation and subsidence of peat. Therefore, the groundwater level is the main control on carbon dioxide emissions from peatlands. Restoring the peatland hydrology is the only way to prevent peat oxidation and mitigate CO₂ emissions. In this study we present a strategy for improved planning of rewetting measures by dam constructions. The study area is a vast peatland with limited accessibility in Central Kalimantan, Indonesia. Field inventory and remote sensing data are used to generate a detailed 3D model of the peat dome and a hydrological model predicts the rise in groundwater levels once dams have been constructed. Successful rewetting of a 590 km2 large area of drained peat swamp forest could result in mitigated emissions of 1.4–1.6 Mt CO₂ yearly. This equates to 6% of the carbon dioxide emissions by civil aviation in the European Union in 2006 and can be achieved with relatively small efforts and at low costs. The proposed methodology allows a detailed planning of hydrological restoration of peatlands with interesting impacts on carbon trading for the voluntary carbon market.     

Reusing colored industrial wastewaters in a photofermentation for enhancing biohydrogen production by using ultrasound stimulated <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis>

One-time ultrasonication pre-treatment of Rhodobacter sphaeroides was evaluated for improving biohydrogen production via photofermentation. Batch experiments were performed by varying ultrasonication amplitude (15, 30, and 45%) and duration (5, 10, and 15 min) using combined effluents from palm oil as well as pulp and paper mill as a single substrate. Experimental data showed that ultrasonication at amplitude 30% for 10 min (256.33 J/mL) achieved the highest biohydrogen yield of 9.982 mL H₂/mL_medium with 5.125% of light efficiency. A maximum COD_total removal of 44.7% was also obtained. However, when higher ultrasonication energy inputs (>256.33 J/mL) were transmitted to the cells, biohydrogen production did not improve further. In fact, 20.6% decrease of biohydrogen yield (as compared to the highest biohydrogen yield) was observed using the most intense ultrasonicated inoculum (472.59 J/mL). Field emission scanning electron microscope images revealed the occurrence of cell damages and biomass losses if ultrasonication at 472.59 J/mL was used. The present results suggested that moderate ultrasonication pre-treatment was an effective technique to improve biohydrogen production performances of R. sphaeroides.     

The complexity of barriers to biogas digester dissemination in Indonesia: challenges for agriculture waste management

In the global south, the use of firewood and LPG as dominant energy sources for cooking contributes to socio-ecological issues. Alternatively, biogas is considered a clean energy source generated from organic waste. However, in Indonesia, until 2018, only less than 2% of households utilized biogas for cooking fuel. This research aims to explore the landscape of biogas governance in Indonesia, its fragmentation, and its relation with biodigester dissemination. This study found that there is fragmentation within small-medium scale national biogas programs in Indonesia. Seven national government biogas programs have similar governance arrangements and characteristics; scattered in different departments within the ministry, using the grant approach with two main vendors, often overlapping with local government programs, and not providing proper monitoring and evaluation mechanism, as well as proper training for users. Meanwhile, the biogas program by a non-government organization utilizes a semi-commercial approach; collaborating with multiple stakeholders (governments, local construction partner organizations, cooperatives, and private sectors-companies and banks); and has standardized training and after-sale services. Within those biogas programs, there are multiple barriers along the supply chain process of biodigester dissemination. These barriers relate to the governance aspect of biogas programs. Fragmented governance affected the capability of each program to tackle barriers in biogas digester dissemination. Besides, heavy subsidy on LPG by the government reduced attraction to biogas. This study shows technology adoption barriers beyond the user/individual aspects. It shows interaction among different factors such as policy, the governance of technology transfer, technical production issues, and socio-cultural problems.

     

Kriging method evaluation for assessing the spatial distribution of urban soil lead contamination

Describing contaminant spatial distribution is an integral component of risk assessment. Application of geostatistical techniques for this purpose has been demonstrated previously. These techniques may provide both an estimate of the concentration at a given unsampled location, as well as the probability that the concentration at that location will exceed a critical threshold concentration. This research is a comparative study between multiple indicator kriging and kriging with the cumulative distribution function of order statistics, with both local and global variograms. The aim was to determine which of the four methods is best able to delineate between "contaminated" and "clean" soil. The four methods were validated with a subset of data values that were not used in the prediction. Method performance was assessed by calculating the root mean square error (RMSE), analysis of variance, the proportion of sites misclassified by each method as either "clean" when they were actually "contaminated" or vice versa, and the expected loss for each misclassification type. The data used for the comparison were 807 topsoil Pb concentrations from the inner-Sydney suburbs of Glebe and Camperdown, Australia. While there was very little difference between the four methods, multiple indicator kriging was found to produce the most accurate predictions for delineating "clean" from "contaminated" soil.