Energy recovery potential in coupling of sanitation and agriculture: Techno-economic analysis on resource-oriented sanitation.

The coupling of sanitation system and agriculture production is essential to mitigate the environmental burden and offset unsustainable fertilizer utilization by employing resource-oriented sanitation. Yet, the economic feasibility and energy recovery potential from domestic waste have rarely been investigated. To assess four scenarios (whether with kitchen waste separation; whether with energy recovery) in the resource-oriented sanitation system, an integrated assessment framework based on energy analysis and techno-economic analysis is employed to investigate the comprehensive sanitation system including both wastewater treatment and solid waste disposal. The results show that energy recovery from human excreta and kitchen waste can offset the energy consumption of the sanitation system and the energy surplus can even be 1067.70 kJ·PE-1·day-1. The optimum covering range of the regional recovery center was quantified from the balance between scale effect and spatial distribution, and the serving inhabitants need to be more than 2800.

Assessment of tear film stability in dry eye with a newly developed keratograph.

PURPOSE: To investigate the applicability of a newly developed corneal topographer in assessing tear film stability. METHODS: This is a prospective, case-control study. Forty-four Chinese dry eye patients and 41 normal subjects were recruited. Noninvasive tear film break-up time (NI-BUT) was measured using a new method based on a corneal topographer equipped with modified scan software. The reliability of the measurements was determined. Then, the correlations between the NI-BUT and the traditional fluorescein tear film break-up time, Schirmer I test values, and inferior tear meniscus height measurements were determined. The receiver operating characteristic curve technique was used to evaluate the NI-BUT examination in the diagnosis of dry eye. RESULTS: In total, a significant difference between the NI-BUT and the fluorescein tear film break-up time was found (3.2 ± 2.3 seconds vs. 5.2 ± 3.4 seconds; P < 0.001). The coefficient of variation and intraclass correlation coefficient values of NI-BUT were 12.8% and 0.93, respectively, for NI-BUT for intraobserver repeatability and 15.4% and 0.88, respectively for interobserver repeatability. The NI-BUT showed a good correlation with other dry eye examinations (all P < 0.05). In addition, the NI-BUT was significantly shorter in dry eye patients (2.0 ± 0.2 seconds) than in normal subjects (4.3 ± 0.3 seconds; P < 0.001). When the cutoff value was set at <2.65 seconds, the sensitivity and specificity of the test were 84.1% and 75.6%, respectively. CONCLUSIONS: Measurements of NI-BUT obtained with the newly developed corneal topographer may provide a simple, noninvasive screening test for dry eyes with acceptable sensitivity, specificity, and repeatability.