Investigation of the direct utilization possibility of methane fermentation residue sludge as liquid fertilizer by micronization.

For establishing a sustainable society, it is crucial to reuse the organic waste as a material resource. Therefore, herein, we aim to pulverize the methane fermentation residue sludge by ball milling and high-speed agitation to directly utilize it as a liquid fertilizer. The solid particles in the sludge can be below 100 µm, corresponding to the nozzle diameter of the boom sprayer by both ball milling and high-speed agitation; when ball milling was carried out for at least 1 h, the ratio of coarse particles larger than 100 µm decreased by less than 10%. In addition, the phosphate-ion concentration in the sludge increased with a decrease in the particle size of solid in the sludge mainly due to increase in its specific surface area. Furthermore, we investigated the effects of various experimental conditions for ball milling on the pulverization efficiency. Results suggests that for grinding the soft solid particles in the sludge by ball milling, the volume ratio of the total medium balls and sludge, total volumes of the balls and sludge, and inner pot volume should be larger, while the ratio of the rotation speed to the critical rotation speed should be almost the same as those reported previously in the reports on grinding of inorganic particles to attain an effective pulverization.

Manure management and pollution levels of contract and non-contract livestock farming in Vietnam.

In analyzing contract farming of livestock production, many studies have focused on the economic aspect. This paper offers the environmental issue by investigating manure management and pollution levels of contract farming (CF) and non-contract farming (NCF) livestock producers in Vietnam. By surveying 270 pig farms and applying logit model, we found that commercial pigpen type of CF reduces the probability of manure separation, while larger garden area and knowledge of composting increase it. By analyzing the wastewater samples collected from 59 farms and employing nearest neighbor matching technique, this paper indicated that CF reduces the pollutants' concentrations in effluents. Using OLS regression models, we found out that manure separation contributes to a reduction in nutrient matters, while biogas plant or combination of biogas plant and stabilization ponds helps to diminish organic matters. The study results suggest that the government should regulate the minimum required land area for installation of the combined manure treatment plants (MTPs). Additionally, to recycle manure and improve nutrient matters in effluent, advanced technologies for separating solid manure are extremely necessary for CF producers. Furthermore, we recommend the government to build mechanisms to compel agribusiness firms engaging in their liability for the environmental side effects caused by their CF producers.

Contaminants in Liquid Organic Fertilizers Used for Agriculture in Japan.

To provide an overview of anthropogenic contaminants in liquid organic fertilizers (LOFs), products from four biogas plants in Kyushu, Japan, were analyzed for a wide range of contaminants, including copper, cadmium, tributyltin (TBT), dibutyltin (DBT), perfluorooctane sulfonate, 952 semi-volatile organic compounds, and 89 antibiotics. The highest concentrations of copper (31.1 mg/L) and cadmium (0.08 mg/L) were found in LOFs from the Hita biogas plant. Only ofloxacin and sulfapyridine were detected in total 89 antibiotics screened. TBT, DBT, and perfluorooctane sulfonate were present at low concentrations in the LOFs from all four locations. Among the 952 semi-volatile organic compounds, 78 compounds were detected in at least one sample and were present at concentrations between 1.2 and 139.6 mg/L. On the basis of comparisons with previous studies and quality standards for the use of organic fertilizers, the concentrations of contaminants in the studied LOFs indicate that they might be safe for agricultural purposes.

Using discrete choice modeling to evaluate the preferences and willingness to pay for leptospirosis vaccine.

Leptospirosis is highly endemic in the Philippines and a serious concern to public health. Local research on candidate vaccine is moving through the development pipeline. The availability of vaccines alone does not guarantee acceptance because individuals' vaccination choice decision is influenced by several factors. This study assessed how vaccine attributes and socio-demographic factors affect the acceptability of leptospirosis vaccine; and estimated individuals' willingness to pay for leptospirosis vaccine. A discrete choice experiment was conducted among leptospirosis and non-leptospirosis case respondents (n = 342) living in Metro Manila. Random Parameters Logit model was used to estimate the relative importance of vaccine attributes and socio-demographic variables on respondents' leptospirosis vaccination choice decision. The estimated model coefficients were used to derive implicit prices and willingness to pay for leptospirosis vaccine. Both case respondents preferred leptospirosis vaccine with 70-100% efficacy, mild to moderate risk of side-effects, given in a single shot, and at a lower price. Non-leptospirosis case respondents preferred a vaccine with 7 to 10 y of protection, while leptospirosis case respondents preferred a vaccine with 10 y protection. The probability of leptospirosis vaccination acceptance was affected by respondents' age, education, family size and income, proximity of home to rivers and sewers, and leptospirosis awareness level. Respondents' willingness to pay for leptospirosis vaccine (US$ 31.14-US$ 65.89) was higher than the Japanese retail price (US$ 21.60-US$ 24.00). Our findings indicated significant potential for introducing leptospirosis vaccine in the Philippine vaccine market. Delivery strategies to ensure equitable access to future leptospirosis vaccine are recommended.

Residents' preferences for household kitchen waste source separation services in Beijing: a choice experiment approach.

A source separation program for household kitchen waste has been in place in Beijing since 2010. However, the participation rate of residents is far from satisfactory. This study was carried out to identify residents' preferences based on an improved management strategy for household kitchen waste source separation. We determine the preferences of residents in an ad hoc sample, according to their age level, for source separation services and their marginal willingness to accept compensation for the service attributes. We used a multinomial logit model to analyze the data, collected from 394 residents in Haidian and Dongcheng districts of Beijing City through a choice experiment. The results show there are differences of preferences on the services attributes between young, middle, and old age residents. Low compensation is not a major factor to promote young and middle age residents accept the proposed separation services. However, on average, most of them prefer services with frequent, evening, plastic bag attributes and without instructor. This study indicates that there is a potential for local government to improve the current separation services accordingly.

Valuing human leptospirosis prevention using the opportunity cost of labor.

Leptospirosis is a serious public health concern in the Philippines, not only because of its increasing incidence rate, but also because of its significant health and economic impacts. Despite its relatively high seroprevalence, knowledge on the economic burden of disease, particularly on the value that the society places on disease prevention remains limited. Obtaining such information is important within the context of public health policy. This study was conducted in Metro Manila to determine the economic burden of leptospirosis, by asking respondents about their willingness to contribute to labor (WTCL) for the prevention of leptospirosis. The respondents pledged an average labor contribution of 10.66 h/month. The average WTCL corresponded to a monetary value of US$4.01 per month when valued using the opportunity cost of labor (leisure rate of time). From the monetized labor contribution, the total economic value of preventing leptospirosis was estimated at US$124.97 million per annum, which represents 1.13% of Metro Manila's gross domestic product (GDP). Estimates from a Tobit regression model identified the respondents' knowledge regarding leptospirosis, the susceptibility of their homes to flooding, and the proximity of their homes to sewers as significant factors to consider when developing resource contribution programs for leptospirosis prevention. More efforts need to be made in developing community level preventive programs, and in improving public's knowledge and awareness about leptospirosis.

Comparison of feeding systems: feed cost, palatability and environmental impact among hay-fattened beef, consistent grass-only-fed beef and conventional marbled beef in Wagyu (Japanese Black cattle).

The objective of this article is to compare feed cost, palatability and environmental impacts among feeding systems of high concentrate (HC), high hay (HH) and grass-only-fed (Gof) groups. Feed cost was the sum of costs paid for feed intake times the price of feed per kilogram. Palatability was measured by a panel taste test using HH and Gof beef and analyzed for differences. Environmental impacts were calculated based on 1 kg of Japanese beef yield of CO(2) equivalents (eq) and animal end weights at each feeding stage. Results showed that the HH and Gof feeding systems could significantly reduce feed costs by approximately 60% and 78%, respectively, from the HC. In the panel taste test, 50% and 47.50% of panelists indicated that HH beef was 'extremely delicious' and 'acceptable,' respectively, while 15% indicated that Gof beef was 'extremely delicious'; 62.50% indicated that Gof beef was 'acceptable.' Environmental impacts of each feeding system in terms of CO(2) equivalents (eq) were 9.32, 6.10 and 2.04 tonnes of eq for the HC, HH and Gof, respectively. The HH was an economical system that produced moderate impacts on the environment and had impressive taste.