Small-scale water reuse for urban agriculture in Namibia: Modeling water flows and productivity

AbstractThroughout the USA, urban agriculture is expanding as a manifestation of an emerging American food politics. Through a case study of Brooklyn, New York, I used mixed qualitative research methods to investigate the political possibilities of urban agriculture for fostering food justice. My findings build on the existing alternative food network (AFN) literature by indicating that problematic contradictions rooted in the neoliberalization of urban agriculture limit the transformative possibilities of farming the city as currently practiced in Brooklyn. I suggest that longstanding agrarian questions—concerns over the relationship between agriculture and capitalism and the politics of small-scale producers—are informative for critical interrogation of urban agriculture as a politicization of food.

Download Full-text

Impact assessment of water and nutrient reuse in hydroponic systems using Bayesian Belief Networks

Journal of Water Reuse and Desalination ◽

10.2166/wrd.2020.026 ◽

2020 ◽

Vol 10 (4) ◽

pp. 431-442 ◽

Cited By ~ 2

Author(s):

Martin Zimmermann ◽

Michaela Fischer

Keyword(s):

Water Reuse ◽

Crop Production ◽

Municipal Wastewater ◽

Expert Knowledge ◽

Research Question ◽

Agricultural Practices ◽

Bayesian Belief Networks ◽

Ecological Impacts ◽

Small Scale ◽

Hydroponic Systems

Abstract Water-saving agricultural practices can reduce negative environmental impacts in water-scarce regions all over the world. This study deals with an innovation that combines hydroponic crop production and municipal wastewater reuse for irrigation purposes. The research question was what impacts such hydroponic water reuse systems have on product confidence, economic viability, groundwater recharge, biodiversity and landscape quality. It should also be clarified under which conditions and with which measures these systems can be sustainable. To answer these questions, a number of generic hydroponic water reuse systems were modeled and assessed using a Bayesian Belief Network that included both numerical values and expert knowledge. The hydroponic water reuse systems with the most positive overall impacts are small-scale food production systems (tomatoes) equipped with lighting and heating whose products are marked with a quality label or with a label for regional products. The systems are located in a former industrial area. In addition, a wetland system and landscape integration are implemented as landscaping measures. Hydroponic systems can be operated economically viable, their products have a high level of product confidence and their ecological impacts can be positive. No tradeoffs have to be accepted between economic, social and ecological goals.

Download Full-text

Light or Dark Greywater for Water Reuse? Economic Assessment of On-Site Greywater Treatment Systems in Rural Areas

Water ◽

10.3390/w13243637 ◽

2021 ◽

Vol 13 (24) ◽

pp. 3637

Author(s):

Eduardo Leiva ◽

Carolina Rodríguez ◽

Rafael Sánchez ◽

Jennyfer Serrano

Keyword(s):

Public Schools ◽

Rural Areas ◽

Water Reuse ◽

Central Zone ◽

Economic Assessment ◽

Economic Feasibility ◽

Operating Costs ◽

Small Scale ◽

Capital Costs ◽

The Impact

Water scarcity is causing a great impact on the population. Rural areas are most affected by often lacking a stable water supply, being more susceptible to the impact of drought events, and with greater risk of contamination due to the lack of appropriate water treatment systems. Decentralized greywater treatment systems for water reuse in rural areas can be a powerful alternative to alleviate these impacts. However, the economic feasibility of these systems must be thoroughly evaluated. This study reports an economic analysis carried out on the viability of greywater reuse considering scenarios with light greywater or dark greywater to be treated. For this, data obtained from the assembly and monitoring of greywater treatment systems located in the north-central zone of Chile, supplemented with data obtained from the literature were used. The results showed that both scenarios are not economically viable, since the investment and operating costs are not amortized by the savings in water. In both evaluated cases (public schools), the economic indicators were less negative when treating light greywater compared with the sum of light greywater and dark greywater as the inlet water to be treated. The investment and operating costs restrict the implementation of these water reuse systems, since in the evaluation period (20 years) a return on the initial investment is not achieved. Even so, our results suggest that the best alternative to reuse greywater in small-scale decentralized systems is to treat light greywater, but it is necessary to consider a state subsidy that not only supports capital costs but also reduces operating and maintenance costs. These findings support the idea that the type of water to be treated is a factor to consider in the implementation of decentralized greywater treatment systems for the reuse of water in rural areas and can help decision-making on the design and configuration of these systems.

Download Full-text

Analysis of Alternatives for Sustainable Stormwater Management in Small Developments of Polish Urban Catchments

Sustainability ◽

10.3390/su122310189 ◽

2020 ◽

Vol 12 (23) ◽

pp. 10189

Author(s):

Joanna Boguniewicz-Zabłocka ◽

Andrea G. Capodaglio

Keyword(s):

Stormwater Management ◽

Water Reuse ◽

Financial Incentive ◽

Local Level ◽

Green Roofs ◽

Source Control ◽

Small Scale ◽

Management Approach ◽

Urban Catchments ◽

Sustainable Stormwater Management

Sustainable stormwater management approaches in accordance with the EU Water Framework Directive (WFD) allow a source control to handle the quality and quantity of the runoff at local level or near the source. The most popular technologies applied in Europe are green roofs, porous pavements, retention basins and bioswales/raingardens. In this article, two of these solutions (retention tank with reuse, and rain garden, respectively), applied to single dwelling case studies in a suburban area in the Silesia Region (Poland), are illustrated and analyzed. The selected cases consider technical and economic aspects as the most important factors for decision on the selection of onsite stormwater management approach. Both systems have been operational for approximately two years. The retention tank proved a good solution, reducing stormwater overflows and allowing local water reuse for lawn irrigation; however, investment and maintenance costs in this case are relatively higher. The raingarden proved to work efficiently in this small scale implementation and implied much lower initial investment and costs. The economic sustainability of these interventions at single dwelling scale was analyzed, showing interesting returns, with outcome depending on the degree of possible water reuse (lower water bills) and availability of fiscal or fee incentives. Introduction of financial incentive schemes will encourage homeowners and developers to implement stormwater control solutions, allowing rapid amortization of investment costs with additional benefits to the community, such as reduced environmental impact of stormwater overflows and possible economies in the construction and management of stormwater systems.

Download Full-text

Comparison of ultraviolet light emitting diodes with traditional UV for greywater disinfection

Journal of Water Reuse and Desalination ◽

10.2166/wrd.2014.022 ◽

2014 ◽

Vol 5 (1) ◽

pp. 17-27 ◽

Cited By ~ 6

Author(s):

M. J. Crook ◽

B. Jefferson ◽

O. Autin ◽

J. MacAdam ◽

A. Nocker

Keyword(s):

Particle Size ◽

Ultraviolet Light ◽

Water Reuse ◽

Light Emitting Diodes ◽

Microbial Inactivation ◽

Small Scale ◽

Light Emitting ◽

Uv Leds ◽

The Impact ◽

Ultraviolet Light Emitting Diodes

The current technological status of ultraviolet light emitting diodes (UV-LEDs) has reached a point where small-scale ultraviolet (UV) water disinfection applications, that is, for greywater reuse appear increasingly promising. This study compares the germicidal and economical aspects of UV-LEDs with traditional UV. Pure cultures and environmental greywater samples were exposed to different radiation doses from both UV sources with the germicidal effect comparative at equivalent doses. The impact of particle size on disinfection efficiency was investigated in two greywater fractions of varying mean particle size. Disinfection efficiency was found to be dependent on particle size with larger particles reducing microbial inactivation for both UV sources. Post-UV blending to detach particle-associated coliforms resulted in higher bacterial counts for both UV sources although to a lesser extent for UV-LEDs suggesting that it might be less affected by the presence of particles than traditional UV sources, possibly due to the UV radiation being emitted by multiple diodes at different angles compared to the traditional UV collimated beam setup. Nevertheless, removal of particles prior to UV disinfection is necessary to meet strict water reuse standards. Although UV-LEDs are currently prohibitively expensive, improvements in performance indicators might make this technology economically competitive within the next few years.

Download Full-text

Institutional challenges and stakeholder perception towards planned water reuse in peri-urban agriculture of the Bengal delta

Journal of Environmental Management ◽

10.1016/j.jenvman.2021.111974 ◽

2021 ◽

Vol 283 ◽

pp. 111974

Author(s):

Kamonashish Haldar ◽

Katarzyna Kujawa-Roeleveld ◽

Marco Schoenmakers ◽

Dilip Kumar Datta ◽

Huub Rijnaarts ◽

...

Keyword(s):

Urban Agriculture ◽

Water Reuse ◽

Bengal Delta ◽

Stakeholder Perception ◽

Institutional Challenges

Download Full-text

Evaporation-induced hydrodynamics promote conjugation-mediated plasmid transfer in microbial populations

ISME Communications ◽

10.1038/s43705-021-00057-5 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Chujin Ruan ◽

Josep Ramoneda ◽

Guowei Chen ◽

David R. Johnson ◽

Gang Wang

Keyword(s):

Antibiotic Resistance ◽

Microbial Communities ◽

Driving Forces ◽

Negative Relationship ◽

Water Evaporation ◽

Small Scale ◽

Surface Deposition ◽

Water Flows ◽

Hydrodynamic Processes ◽

Plasmid Conjugation

AbstractConjugative plasmids bestow important traits to microbial communities, such as virulence, antibiotic resistance, pollutant biotransformation, and biotechnology-relevant functions. While the biological mechanisms and determinants of plasmid conjugation are well established, the underlying physical and ecological driving forces remain unclear. Microbial communities often inhabit unsaturated environments, such as soils and host surfaces (e.g., skin, teeth, leaves, roots), where water evaporation and associated small-scale hydrodynamic processes frequently occur at numerous air-water and solid-water interfaces. Here, we hypothesized that evaporation can induce water flows with profound effects on the spatial distribution and surface deposition of cells, and consequently on the extent of plasmid conjugation. Using droplet experiments with an antibiotic resistance-encoding plasmid, we show that evaporation-induced water flows reduce cell-cell distances and significantly increase the extent of plasmid conjugation. Counterintuitively, we found that evaporation results in lower expression levels of conjugation-related genes. This negative relationship between the extent of plasmid conjugation and the expression of conjugation-related genes could be attributed to increased conjugation efficiency during evaporation. This study provides new insights into the physical and ecological determinants of plasmid conjugation, with important implications for understanding the spread and proliferation of plasmid-encoded traits.

Download Full-text

Non-biological methods for phosphorus and nitrogen removal from wastewater: A gap analysis of reinvented-toilet technologies with respect to ISO 30500

Gates Open Research ◽

10.12688/gatesopenres.12931.2 ◽

2020 ◽

Vol 3 ◽

pp. 559 ◽

Cited By ~ 1

Author(s):

Lena Trotochaud ◽

Brian T. Hawkins ◽

Brian R. Stoner

Keyword(s):

Nutrient Removal ◽

Water Reuse ◽

Emerging Technologies ◽

Gap Analysis ◽

Small Scale ◽

Nitrogen And Phosphorus ◽

Technological Advances ◽

Removal Technologies ◽

Sanitation Systems ◽

Biological Methods

The aims of the Reinvent the Toilet Challenge (RTTC) include creation of an off-the-grid sanitation system with operating costs of less than US$0.05 per user per day. Because of the small scale at which many reinvented toilets (RT) are intended to operate, non-biological treatment has been generally favored. The RTTC has already instigated notable technological advances in non-sewered sanitation systems (NSSS). However, increasingly stringent liquid effluent standards for N and P could limit the deployment of current RT in real-world scenarios, despite the urgent need for these systems. The newly adopted ISO 30500 standards for water reuse in NSSS dictate minimal use of chemical/biological additives, while at the same time requiring a 70% and 80% reduction in total nitrogen and phosphorus, respectively. This document provides a brief overview of the mature and emerging technologies for N and P (specifically ammonia/ammonium and orthophosphate) removal from wastewater. At present, the dearth of nutrient removal methods proven to be effective at small scales is a significant barrier to meeting ISO 30500 standards. Closing the gap between RTs and ISO 30500 will require significant investments in basic R&D of emerging technologies for non-biological N and P remediation and/or increased reliance on biological processes. Adaptation of existing nutrient-removal technologies to small-scale NSSS is a viable option that merits additional investigation.

Download Full-text