Greenhouse gas emissions and carbon footprint of maize-based feed products for animal farming in Thailand.

Due to the growing demand for livestock products both within the country and in foreign markets, there is a need to boost the production of maize-based animal feed in Thailand. However, greenhouse gas (GHG) emissions and the potential for reducing these emissions through the production of various types of animal feed remain ambiguous. Thus, this study is aimed at estimating GHG emissions from broiler, layer, and swine feed production in Thailand and identifying economic advantages of alternative methods to mitigate those emissions. Field surveys were carried out to quantify the input and output of energy and materials in 10 commercial feed mills so as to determine greenhouse gas emissions using proper emission factors. The scope of this study is based on the cradle-to-gate approach. The functional unit used for greenhouse gas evaluation was kg CO2-eq/t of feed. Total greenhouse gas emissions from broiler, layer, and swine feed production were found to be 650 ± 20, 706 ± 20, and 466 ± 20 kg CO2-eq/t of feed, respectively. Layer feed production created the highest greenhouse gas emissions, 1.09 and 1.52 times that of broiler and swine feed production, respectively. This is because layer feed required intensive fish meal (FM) as protein sources for improving egg quality. In broiler and swine feed production, the most significant emissions are attributed to the use of maize grain (MG) and soybean meal (SBM) as sources of carbohydrate and protein in those feeds. However, animal feed production operation at the existing condition still emits CO2 to the atmosphere as CO2 fixation efficiencies of 69.3, 67.5, and 75.9% for broiler, layer, and swine feed, respectively. From the sustainable resource consumption scenarios in broiler, layer, and swine feed production, approximately 39.6, 49.6, and 43.3% reduced carbon emissions could be achieved by using MG rotated with SB in the maize plantation phase and substituting FM, wheat grain and fossil fuel needed in the manufacturing process with SBM, locally-produced tapioca chips and biomass energy. Consequently, the potential cost savings of such replacements were determined to be 54.0, 62.5, and 29.7 USD/t of feed, respectively.

Enhancing chemical phosphorus precipitation from tapioca starch anaerobic digestion effluent in a modified pilot-scale fluidized bed reactor.

This study aimed to evaluate the possibility of P precipitation as struvite from real anaerobic digestion (AD) effluent of tapioca starch processing. The results showed that at a pH of 9, and without Mg:P molar adjustment, P recovery was at 85%. The percentage of P recovery was increased to 90% and P contained in precipitates was at 11.80-14.70 wt% P, which is higher than commercial single superphosphate fertilizer (SSP, 18-22 wt% P2O5). This was achieved by controlling mixing at 200-400 rpm and upflow velocity at 50-200 cm min-1 inside a fluidized bed reactor (FBR). Based on SEM-EDX, powder XRD, phase identification by profile matching, and FT-IR analysis, the results demonstrated that recovered precipitates formed struvite predominantly. In addition, results of the woodchip ash additions and the one-way ANOVA based-RSM analysis revealed that mixing, the solution pH, and the woodchip ash intensely affected P recovery with the optimum condition found at 400 rpm, pH9, 4 g L-1, respectively. Ash addition enhanced P recovery efficiency but decreased the product's purity. Total costs of P recovery varied considerably from 0.28 to 7.82 USD∙(kg P)-1 depending on chemical consumption and %P content in recovered products. Moreover, the total cost was reduced by 57% from 7.82 USD∙(kg P)-1 (profit margin: -4.30 to -2.82) by a single mixing operation to 3.35 USD∙(kg P)-1 (profit margin: +0.17 to +1.65) employing coupling effect of mixing and Vup. The results indicate that P recovery from tapioca starch AD effluent not only provides a good-quality alternative slow-release P fertilizer, but also helps to curtail environmental problems due to excessive P and nitrogen discharge. These findings also demonstrate the ways of recovering nutrients from an abundant renewable resource that are relevant to simultaneous waste utilization during pollution controls.

Enhancing anaerobic co-digestion of primary settled-nightsoil sludge and food waste for phosphorus extraction and biogas production: effect of operating parameters and determining phosphorus transformation.

The study aimed to comprehensively determine P extraction efficiency and co-digestion of food waste (FW) and primary settled-nightsoil sludge (PSNS) process performance influenced by different hydraulic retention times (4, 7, 10, and 15 days) and mixture ratios of FW:PSNS in substrates (100:0, 75:25, 50:50, 25:75, and 0:100). P-transformation was evaluated to identify P fractionation in both supernatant and sludge accumulated in reactors. The results showed that anaerobic co-digestion was inhibited by the accumulation of undigested feedstock due to higher %PSNS found in AD4 (25FW:75PSNS) and AD5 (100PSNS). A more stable process was found in AD2 (75FW:25PSNS) under hydraulic retention time (HRT) 15 days in which COD removal efficiency and P release were 97.2 and 80.2%, respectively. This recommended condition allowed a high organic loading rate (OLR) at 12 gVS/L/day resulting in the highest biogas yield of 0.93 L/L/day. Distribution of P data demonstrated that most of P in feedstock was deposited and accumulated in sediment up to 97.8%. Poor biodegradability resulting from using shortened HRT led to high increased P-solid content in effluent. In addition, available P in effluents and accumulated P-solids in sediment obtained from the AcoD process has the potential to serve as sources for P recovery.

Product and cost perspectives of phosphorus recovery from human urine using solid waste ash and sea salt addition - A case of Thailand.

Phosphorus (P) recovery from human urine was evaluated using the addition of MgCl2, sea salt and solid-waste (SW) incinerated ashes. The study objectives were to assess and compare their efficiency for P recovery, costs of chemicals added and relevant crystal characteristics. Results from the experiments conducted between pH range of 7-11 revealed that P precipitation efficiency was increased to 89-97% and 72-88% when MgCl2 and sea salt were added, respectively. Precipitates obtained from both cases were found to contain 10.8-17.1% P dry weight which is superior to commercial fertilizer (8.80% P). Based on SEM-EDS examination and chemical equilibrium thermodynamics, about 83% and 68% of precipitates were in the form of struvite for the addition of MgCl2 and sea salt, respectively. Although 18% less struvite was formed with sea salt added, cost was found to be reduced from 4.07 USD·(kg P)-1 for MgCl2 addition to 2.91 USD·(kg P)-1 using sea salt addition, representing a 28% cost reduction. Furthermore, SW ashes added into the urine increased P recovery efficiency about 6-17%. Addition also lowered the costs to 1.75 and 1.68 USD·(kg P)-1 for SW fly ash and bottom ash, respectively. Thus, ash addition reduced cost and provided an alternative to landfill disposal. However, addition of SW bottom ash might result in recovered P solids with lead concentration exceeding the EC limit for inorganic fertilizer. In summary, results of this study have demonstrated a pragmatic way to recover P from human urine with the use of sea salt and ash as alternative Mg source and seed. Results indicate that this practice not only produces a good-quality fertilizer as struvite for sustainable P management, but also helps protect the water environment, and support circular economy of P in human ecosystem.

Green residues from Bangkok green space for renewable energy recovery, phosphorus recycling and greenhouse gases emission reduction.

Effective ways to integrate human life quality, environmental pollution mitigation and efficient waste management strategies are becoming a crisis challenge for sustainable urban development. The aims of this study are: (1) to evaluate and recommend an optimum Urban Green Space (UGS) area for the Bangkok Metropolitan Administration (BMA); and (2) to quantify potential renewable resources including electricity generation and potential nutrient recovery from generated ash. Green House Gases (GHGs) emissions from the management of Green Residues (GR) produced in a recommended UGS expansion are estimated and compared with those from the existing BMA waste management practice. Results obtained from this study indicate that an increase in UGS from its current 2.02% to 22.4% of the BMA urban area is recommended. This optimum value is primarily due to the area needed as living space for its population. At this scale, GR produced of about 334kt·y-1 may be used to generate electricity at the rate of 206GWh·y-1 by employing incineration technology. Additionally, instead of going to landfill, phosphorus (P) contained in the ash of 1077 t P·y-1 could be recovered to produce P fertilizer to be recycled for agricultural cultivation. Income earned from selling these products is found to offset all of the operational cost of the proposed GR management methodology itself plus 7% of the cost of BMA's Municipal Solid Waste (MSW) operations. About 70% of the current GHGs emission may be reduced based on incineration simulation.

Phosphorus leakage from fisheries sector - A case study in Thailand.

Although phosphorus (P) is an essential element needed for all lives, excess P can be harmful to the environment. The objective of this study aims to determine P flows in the fisheries sector of Thailand consisting of both sea and freshwater activities of captures and cultures. Currently, the annual fisheries catch averages 3.44 ± 0.50 Mt. Most comes from marine capture 1.95 ± 0.46 Mt, followed by coastal aquaculture 0.78 ± 0.09 Mt, freshwater aquaculture 0.49 ± 0.05 Mt, and inland capture 0.22 ± 0.01 Mt. Of this total, about 11% is contained in fresh products directly sold in local markets for consumption, while 89% is sent to processing factories prior to being sold in local markets and exported. The quantities of P entering the fisheries sector come from captures, import of fisheries products and feed produced from agriculture. This P input to the fisheries sector is found to average 28,506 t P.y-1 based on the past ten-year records. Of this total, P input from captures accounts for 76%; while, 11% represents aquatic feeds from agriculture and animal manures. About 13% is obtained from the imports of fishery products. Coastal and freshwater aquacultures are found to be P consumers because their feeds are almost all produced from agricultural crops grown inland. Moreover, these activities cause most of P losses, approximately 10,188 t P·y-1, which account for 89% of the total P loss from the fisheries sector. Overall, P in the fisheries sector is found to mobilize through three channels: (a) 44% is consumed within the country; (b) about 16% is exported; and, (c) 40% is lost from the ecosystem. Based on the results of this work it is recommended that future research be directed on ways to minimize P loss and maximize P recycle in Thailand's fisheries sector as to enhance its food security and curtail water pollution.

Quantification of phosphorus flows throughout the consumption system of Bangkok Metropolis, Thailand.

Due to unequal distribution of the world's Phosphorus (P) sources for fertilizer production, an evaluation of P flows throughout the consumption system of a city is needed. The prime objective of this paper is to assess and prioritize P recovery options as to bring about, as much as possible, a close-looped P-for-food system. Using the Bangkok Metropolitan Administration (BMA) as a case study, the aim of this work is to quantify the potential mass flow of P for four major types of urban wastes: domestic wastewater (DWW), septage sludge (SS), food waste (FW) and green garbage (GB) and to determine the recoverable stock of P available. The consumption of food and supplements such as cleansing products and fertilizer is estimated at a rate of 1146.4 g P·cap(-1)·year(-1). P contained in wastes being discarded from its average 7.9 million population plus 33.8 million Bangkok-visiting tourists per annum is determined to be 8.01 kt P annually. Only 4% of the above quantity is recycled and used internally for cultivating plants grown in public parks. An annual amount of 7.68 kt P was found to be disposed of in landfills (6.23 kt P) and in the river systems (1.45 kt P). From the findings of this study, therefore, it is recommended that P recovery efforts from BMA's urban wastes should be focused on wastes enrouted to landfills since these constitute 81% of P discarded. As a consequence, solid waste combustion coupled with energy recovery from P-binding organics may be an appropriate means of P recovery. This technology has the potential to reduce waste volume, generate electricity, and produce P-containing ash that can be used for further application on farm lands.

Carbon balance in municipal solid waste management--a case study of Nonthaburi municipality, Thailand.

OBJECTIVE: This research aimed to investigate the carbon equivalences associated with the unit processes of municipal solid waste management (MSWM) in Nonthaburi municipality. In addition, factors affecting MSWM's carbon-related activities were determined to find the reduction potential of carbon emissions into the atmosphere. MATERIAL AND METHOD: Afield survey was conducted to quantify the amount of resources used in MSWM. Then, they were evaluated in terms of carbon equivalences occurring in the process scheme and categorized into carbon emissions, fixation and reduction,following a carbon-balanced model. RESULTS: From carbon balance analysis of the base-line-scenario MSWM, the carbon emissions were found to be -2,374.56 MTCE/y, resulting in the average carbon unit of-22.98 kg CE/ton solid waste. The negative sign indicates a carbon reduction, instead of an emission,from this MSWM practice, which helps to reduce the concentration of carbon dioxide in the atmosphere. CONCLUSION: The results of the model reveal that the highest contribution to carbon reduction potential in MSWM is recycling. Accordingly, it is strongly recommended that a policy promoting reuse, recovery, and recycling be pursued in every step of MSWM to assist in, not only extending landfill service life span, but also alleviating the increasing global warming problems.

Biomass production of papyrus (Cyperus papyrus) in constructed wetland treating low-strength domestic wastewater.

In this study, the pilot-scale constructed wetlands were fed with low-strength domestic wastewater to investigate the energy-capturing efficiency and plant productivity. Papyrus was a selected emergent macrophyte planted in the systems. The wastewater was intermittently fed to the systems, corresponding to the organic loading rates of 10, 16, 31, and 63 kg BOD/ha-d. With abundant sunshine in the tropical-climate area, papyrus converted solar radiation to biomass of about 2200-3100 g dry weight/m(2) from the two-month period of the experiments. Furthermore, the energy contents of papyrus are 16.2, 17.2, and 16.8 MJ/kg for culms, umbels, and total above-ground parts, respectively. From the plant productivity and the energy contents of papyrus obtained from this study, the energy capturing efficiencies can be estimated to be in the range of 4.4-6.0%, which are relatively high, compared with those of other plants.