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Global water provision challenges have promoted decentralized water supply alternatives such as rainwater harvesting systems (RWHS). RWHS sustainability demands involve social, technical, and economic criteria in planning. Generally, in rural areas, water provision is more complex due to multiple uses of water, scattering of households, and low economies of scale. This research proposes a multicriteria tool for selecting RWHS in rural areas, considering social, technical, and economic criteria. The tool was developed by systematically identifying subcriteria and their hierarchization through the analytical hierarchy process (AHP), the technique for order of preference by similarity to ideal solution (TOPSIS), and a case study validation. Seven subcriteria were identified. The hierarchy of criteria was social (49.7%), technical (26.4%), and economic (23.9%). The tool involved: (i) users' consultation about the perceived ease of use and availability of water sources other than rainwater; (ii) system dimensioning to establish supply size, maintenance requirements, and required water quality; and (iii) costs and benefits estimation. Tool validation in a rural area included the evaluation of the alternatives proposed: (a) alternative 1: potable domestic uses (PD) and non-potable (NPD); (b) alternative 2: PD and NPD, irrigation of crops and chicken farming for self-consumption; and alternative 3: PD and NPD and chicken farming for profit sale. The sensitivity analysis showed the tool's consistency and robustness. Tool validation highlights the importance of integrating the three dimensions in selecting RWHS. The study provides a systematic methodology to assess and prioritize RWHS, appealing to policymakers, engineers, and practitioners facilitating water management and supply processes in rural areas. [ABSTRACT FROM AUTHOR]

Landslides represent geological hazards wherein a part of a slope loses its static equilibrium and initiates movement. Once this movement begins, it becomes crucial to evaluate the land-slide runout distance (LRD). Currently, there exist numerous tools for estimating LRD, among which geometrical approximations stand as one of the most popular. These empirical models are particularly useful for wide-scale studies, aiding in the scale-down of the problem by identifying the critical areas. This study examines the application of geometrical approximations in the Colombian north–east Andean region. Within this area, a sampling of 49 was conducted using photogrammetric techniques, enabling the morphometrical characterization of each study unit. The results showcase the relationship between geometrical characteristics and LRD in the studied area, considering both land use and geomorphological settings. By exploiting these relationships, the study compares the estimation of LRD using various empirical models, many of which are already employed by practitioners within the studied region. For instance, the relationships in literature display a relative error in the estimation ranging around −50% and 100%. Furthermore, this research proposes new relationships for estimating LRD, enhancing the error estimations in a range between 0% and 50%, highlighting both the advantages and limitations of such empirical estimations. Consequently, it contributes new data to enrich the field of LRD studies. [ABSTRACT FROM AUTHOR]

Composting is a sustainable alternative for green waste (GW) valorization contributing to the circular bioeconomy. However, the processing time must be reduced and the end-product quality must be improved. This study determined the effect of the incorporation of processed food waste (PFW), unprocessed food (UPFW), sawdust (SW), phosphate rock (PR) and a specific bacterial inoculum on GW-composting process parameters and product quality. Three treatments were evaluated in 120 kg piles: (i) TA: (GW + UPFW + PFW + inoculum), (ii) TB (GW + UPFW + PFW), and (iii) TC (GW). An inoculum of Bacillus sp. and Paenibacillus sp. was incorporated in the cooling phase for TA. On the other hand, the effect of the inoculum at the laboratory scale (20 kg reactors) was compared with that found at the pilot scale (120 kg piles). The incorporation of FW, SW, PR and the inoculum increased the amount of lignocellulose biodegradation (TA: 29.1%; TB: 22.7%; TC: 18.2%), which allowed for a reduction of up to 14 days of processing time. The product obtained for TA had a similar quality to the other two treatments, although a lower phytotoxicity was determined according to the germination index (TA: 95%; TB: 85%; and TC: 83%). The final product of TA showed the best agricultural characteristics with pH 8.3, TOC of 24.8%, TN of 1.32%, and GI of 98.8%. Finally, the scaling effect with the bacterial inoculum was shown to affect parameters such as the TOC, TN, GI, and, to a lesser extent, temperature and pH. The results obtained in this paper highlight the importance of optimizing the composting of GW, specifically with the use of co-substrates and specific inocula, which can be of interest for composting materials with a high content of lignocellulose such as GW. [ABSTRACT FROM AUTHOR]

Páramos are high mountain ecosystems strategic for water provision in South America. Currently, páramos are under threat due to agricultural intensification that impairs surface water sources. This research analyzed the effect of agriculture (spring onion—Allium fistulosum, potato—Solanum tuberosum, and livestock farming) on water quality in páramo ecosystems. A Hydrographic Unit upstream of the Jordan river catchment (Colombia) was selected and monitored in two different rainfall regimes, following the paired catchments and upstream-downstream approaches to compare water quality from natural and anthropic areas. Twenty-two parameters related to agricultural activities were analyzed (nutrients, salts, organic matter, sediments, and pathogens). The studied agricultural activities increased loads of surface water in quality in nitrates (0.02 to 2.56 mg N-NO3/L), potassium (0.13 to 1.24 mg K/L), and Escherichia coli (63 to 2718 FCU/100 mL), generating risks on the human health and promoting eutrophication. Total nitrogen and organic matter in the rainy season were higher than dry. BOD5, COD, turbidity, and E. coli were above international standards for direct human consumption. However, water could be used for irrigation, livestock watering, and aquatic life ambient freshwater. The results show that a small land-use change of almost 15% from natural páramo vegetation to agricultural uses in these ecosystems impairs water quality, limiting its uses, and the need to harmonize small-scale livelihoods in the páramo with the sustainability of ecosystem service provision. [ABSTRACT FROM AUTHOR]

Composting is a promising process for green waste (GW) management. However, reducing the processing time and increasing end-product quality are aspects to be improved. A strategy to optimize GW composting is using bacterial strains and microbial consortia that stimulate lignocellulose degradation. This work systematically analyses the research trends on the use of those bacterial inoculants and microbial consortia. The information was analyzed according to three topics: (i) microbial role in the process; (ii) process optimization; and (iii) end-product quality. Research needs identified by our research include: (i) selection of bacterial consortia and optimization of inoculum concentration; (ii) correlation between enzymatic activity of indigenous and exogenous bacteria and nitrogen availability during the process; and (iii) stimulation of lignocellulose degradation and formation of humic substances considering end-product quality. This research contributes to planning future research endeavors related to the use of microbial inoculants to optimize GW composting. [ABSTRACT FROM AUTHOR]

Composting is an adequate method for treating and valorizing agricultural waste such as those from spring onion (SO) cultivation and chicken breeding (chicken manure–CM). However, the low content of Total Organic Carbon in the waste from SO and the high concentration of total nitrogen in CM are limitations for the composting process. This research studied the co-composting of SO and CM in a moorland ecosystem, together with locally available co-substrates such as biowaste (BW) and woodchips (WC), focusing on the effect of co-composting in process development and end-product quality. A pilot-scale experiment was carried out using three treatments in triplicated composting piles: (i) Treatment A: 43% CM + 41% BW + 16% WC; (ii) Treatment B: 52% CM + 32% SO + 16% WC, and (iii) Treatment C: 70% SO + 30% WC. Treatments A and B reached thermophilic temperatures after two days of the process start and remained at that level for 17 days. However, treatment B reached environmental temperature during curing in a shorter time (43 days) than treatment A (53 days). Treatment C did not achieve thermophilic temperatures. Tests carried out at the end of the process showed end-product stability and non-phytotoxic characteristics (germination indexes 80%). The fertility index of the products showed that treatments A and B presented values of 4.3 (over 5.0) while treatment C obtained a value of 2.5. From the perspective of agricultural use, products from the three treatments had limitations due to deficiencies in essential nutrients like phosphorus. Still, they had potential as a soil amendment for restoration processes. In summary, we have demonstrated that this waste, in combination with other organic materials, could be a good amendment for the composting process and the end product. [ABSTRACT FROM AUTHOR]

To improve the financial sustainability and business management of composting facilities, mostly small-scale and manually operated facilities, the simultaneous optimization of the process and quality of the final product must be prioritized. This study used artificial neural networks (ANNs) and particle swarm optimization (PSO) as tools to evaluate the composting of biowaste (BW) with different cosubstrates (i. star grass (SG) and ii. a SG and sugarcane filter cake (SFC) mixture). The simulation aimed to maximize product quality in the shortest processing time by varying the mixing ratio and turning frequency. The simulation showed optimal conditions with a turning frequency of twice per week with the following mixtures: (i) BW:SG (72.9:27.1), 76 days of processing; and (ii) BW:SFC:SG (60:16:24), 88 days of processing. The results showed the effect of the type of carbon source in the cosubstrates on the retention time, which may imply the need for a larger area in composting facilities. On the other hand, the findings show that a minimum time is required to achieve a product that meets quality standards, although a longer processing time reduces the agricultural value of the compost. This model can be used to define design criteria and operating conditions and select a cosubstrate that can contribute to improving the agricultural quality of the final product. [ABSTRACT FROM AUTHOR]

Green waste (GW) management is a key issue due to its high production rate and its variety of physical properties and chemical composition. Composting is a promising alternative for GW treatment and valorization. However, the presence of recalcitrant components such as lignin and cellulose increase the processing time. Strategies such as addition of co-substrates and operative modifications have improved the processing time and compost quality. Therefore, in this study, three strategies have been implemented (i) addition of unprocessed food (UF) and processed foods (PF) as co-substrates for GW to improve the nutrients composition of the substrates at the beginning of the process, (ii) addition of phosphate rock (PR) to improve product quality, and (iii) the use of two-stage composting (TSC) to accelerate the degradation. For this purpose, three treatments with the same mixture (48% GW + 21% UF + 18% PF + 13% sawdust (SW)) were conducted: (i) TA (TSC + 15% PR), (ii) TB (traditional composting +15% PR), and (iii) TC (traditional composting). TSC did not show significant differences compared with TC regarding the process and compost quality, while the addition of PR increased the phosphorus content of the product. However, TC produced the compost with the highest quality according to the Colombian legislation for soil amendment. [ABSTRACT FROM AUTHOR]

A novel approach to optimize the composting process of biowaste (BW) mixed with sugarcane filter cake (SFC) and the product quality was attempted in the present study by adopting Artificial Neuronal Network (ANN) and the particle swarm optimization (PSO) algorithm. The effectiveness of the co-composting process depends on operational parameters such as Mixing Ratio (MR) and Turning Frequency (TF). Using the optimization of these factors, the process time can be reduced while product quality can be maximized. This study includes the simultaneous evaluation of both operational parameters, with SFC being the amendment material (BW:SFC MR of 90:10, 80:20 and 70:30) and a TF of 1, 2 and 3 turnings per week. The simultaneous effect of the two operational parameters was evaluated using a central composite design. ANN was used to predict the behaviour of the response parameters, and the PSO algorithm was used to optimize the process and the final product quality. The results of the simulations with ANN suggest that the BW:SFC ratios of 81:19 and 75:25, with a TF of two times/week and an estimated operation time of 76–94 days, correspond to a final product with the most adequate physicochemical quality for agricultural use. The optimization with PSO showed the optimal local at a BW:SFC MR of 76.9:23.1 with a turning frequency of two times weekly. An 80-day process is recommended to optimize the final product quality. The model can be useful to define design criteria and operational conditions during biowaste composting. [ABSTRACT FROM AUTHOR]

Although composting is an effective option for the use of biowaste (BW), its physicochemical quality has limiting conditions (e.g., low C/N ratio, phosphorus and high moisture) that affect the process and the quality of the product. The incorporation of amendment materials (AM) and the variation in the turning frequency (TF) are two of the most widely used operational strategies to improve these limiting conditions. However, the effect of the simultaneous application of these two strategies on the BW composting process has been few studied. In this article, the inclusion of sugarcane filter-cake (SFC) as an AM in BW at several mixing ratios (BW:SFC (w/w); 100:00, 90:10, 80:20 and 70:30) and three TFs (1, 2 and 3 turnings/week) was evaluated at a pilot scale. A Box-Behnken experimental design was used to analyse the simultaneous effects of the two strategies. Results showed that the application of both operational strategies simultaneously has a significant effect (p ≤ 0.05) on process parameters [i.e., stabilization time, temperature, pH, oxygen concentration, Total Organic Carbon (TOC), Total Nitrogen (TN) and Total Phosphorus (TP)] and on product quality. A mixture ratio of 80:20% (BW:SFC) and a TF of 2 reduced processing time by 13 days compared to the control treatment, maintained temperatures above 65 °C and increased the TOC (> 15%), TN (2.4%) and TP (1.6%) contents at the end of the composting process, thus improving the quality of the final product. [ABSTRACT FROM AUTHOR]

Water availability pressures, competing end-uses and sewers at capacity are all drivers for change in urban water management. Rainwater harvesting (RWH) and greywater reuse (GWR) systems constitute alternatives to reduce drinking water usage and in the case of RWH, reduce roof runoff entering sewers. Despite the increasing popularity of installations in commercial buildings, RWH and GWR technologies at a household scale have proved less popular, across a range of global contexts. For systems designed from the top-down, this is often due to the lack of a favourable cost-benefit (where subsidies are unavailable), though few studies have focused on performing full capital and operational financial assessments, particularly in high water consumption households. Using a bottom-up design approach, based on a questionnaire survey with 35 households in a residential complex in Bucaramanga, Colombia, this article considers the initial financial feasibility of three RWH and GWR system configurations proposed for high water using households (equivalent to >203 L per capita per day). A full capital and operational financial assessment was performed at a more detailed level for the most viable design using historic rainfall data. For the selected configuration (‘Alt 2’), the estimated potable water saving was 44% (equivalent to 131 m3/year) with a rate of return on investment of 6.5% and an estimated payback period of 23 years. As an initial end-user-driven design exercise, these results are promising and constitute a starting point for facilitating such approaches to urban water management at the household scale. [ABSTRACT FROM AUTHOR]

The composting of green waste (GW) proceeds slowly due to the presence of slowly degradable compounds in that substrate. The introduction of amendments and bulking materials can improve organic matter degradation and end-product quality. However, additional strategies such as two-stage composting, can deal with the slow degradation of green waste. This paper evaluates the effect of two-stage composting on the process and end-product quality of the co-composting of green waste and food waste amended with sawdust and phosphate rock. A pilot-scale study was developed using two treatments (in triplicate each), one being a two-stage composting and the other being a traditional composting. The two treatments used the same mixture (wet weight): 46% green waste, 19% unprocessed food waste, 18% processed food waste, 13% sawdust, and 4% phosphate rock. The traditional composting observed a higher degradation rate of organic matter during the mesophilic and thermophilic phases and observed thermophilic temperatures were maintained for longer periods during these two phases compared to two-stage composting (i.e., six days). Nonetheless, during the cooling and maturation phases, the two treatments had similar behaviors with regard to temperature, pH, and electrical conductivity, and the end-products resulting from both treatments did not statistically differ. Therefore, from this study, it is concluded that other additional complementary strategies must be evaluated to further improve GW composting. [ABSTRACT FROM AUTHOR]

Rural water supply systems (RWSS) in developing countries typically have deficiencies that threaten their sustainability. This research used Multi-Criteria Analysis and the Analytical Hierarchy Process to identify indicators that can be used to assess the sustainability of RWSS. The assessment tool developed is composed of 17 attributes with 95 quantifiable indicators. The tool enables the assessment of the sustainability of RWSS, using data collected through semi-structured interviews, social cartography, technical inspection, household surveys, and water monitoring. The tool was applied in a case study of a RWSS in the Andean region of Colombia, illustrating a participatory, holistic, and structured assessment that provided a single sustainability measure for the system (3.0/5.0). The tool's completeness is represented by its extensive attributes and indicators that deliver a robust baseline on the state of a system, help identify improvement strategies, and monitor system performance over time that can assists rural community organizations with RWSS management. [ABSTRACT FROM AUTHOR]