In order to sustain food production in a resource-scarce scenario it is vital that maximum utility is derived from available reserves while simultaneously promoting their recycling. Further, substantial value can be sourced if approaches are devised that utilize resources that were erstwhile considered wastes. To look towards alternative fertilization techniques, this study suggests a novel fertilizer combination of two waste products: low-grade Rock Phosphate (RP) tailing and human urine. It is demonstrated that the combined use of urine (nitrogen) and low-grade RP (phosphorous) can indeed act as a substitute to synthetic inorganic fertilizers. Crop trials were carried out for Cicer arietinum using RP enriched urine at various application rates on a red loamy soil (pH of 8.11). Observations made from plant growth response indicated that direct application of this fertilizer combination resulted in performance equivalent to mineral fertilizer Di-Ammonium Phosphate added in the same ratio. The use of RP enriched urine thus holds a lot of promise for simultaneous waste minimization, waste utilization, and improved resource-use efficiency. © 2016 The Institution of Chemical Engineers.

Mahesh Ganesapillai

Department of Chemical Engineering

School of Chemical Engineering

Vellore Campus

Simha P

Beknalkar S.S

Sekhar D.M.R.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Sustainable Production and Consumption

The present study argues that human excreta are vital, renewable biological resources (nutrients) which must be considered an important subset of a bio–based economy. A human excreta based bio–economy can be defined as a set of circular and sustainable approaches that promote closed–loop flows of resources and nutrients from sanitation to agriculture. To this effect, from a technological perspective, this study presents a pathway for recovering, concentrating, and reusing fertilizer products from human urine. The development and implementation of urine diversion technologies have facilitated large–scale separation and storage of human urine independent of the faeces; however, processes that help harness the fertilization potential of source–separated urine in an effective, simple, yet efficient manner remain to be found. Hence, this study demonstrates a simple approach to selectively strip urea (a value–added product) from human urine in a continuously operated column packed with activated carbon prepared from agricultural wastes (coconut shells). Investigations were performed to determine the effect of carbon bed height, urine flow rate and concentration on efficiency of urea recovery. In order to model the column breakthrough and understand interactive influence of process parameters, experimental data was modelled against four well–known breakthrough equations. Optimal operating conditions were identified through an objective of simultaneous maximization of column capacity and urea removal efficiency of the activated carbon as well as minimization of sorption time. An initial urea concentration of 60%, urine flow of 6 L h−1 and carbon bed height of 30 cm resulted in 80% urea removal and an equilibrium uptake capacity of 94.03 mg g−1. For quantitative recovery of the adsorbed urea and reuse of the saturated column, regeneration experiments were performed using deionised water as the desorption media pumped in up flow mode at 3 L h−1. Considering the average annual nutrient composition of human urine, this approach could allow production of ∼4.5 kg urea per person per year. The reutilization of human wastes through ecologically–conscious sanitation practices could therefore blur the difference in the cognition of two human constructs, ‘resources’ and ‘wastes’. © 2017 Elsevier Ltd

Journal of Cleaner Production

Continuous urea–nitrogen recycling from human urine: A step towards creating a human excreta based bio–economy

To address the shortcomings of modern wastewater treatment, Ecological Sanitation (EcoSan) has been advocated as a sustainable approach to promote closed-loop flows of resources and nutrients from sanitation to agriculture. In this study, we discuss the rationale behind its conception and provide a state-of-the-art review on the subject. Through an exhaustive literature analysis of EcoSan systems, its historical developments and programs implemented worldwide we (i) validate the potential applicability and feasibility of decentralized, source-based sanitation and (ii) depict fundamental problems in EcoSan systems design that have stalled its adoption and proliferation. Specifically, we focus on urine diversion to demonstrate its potential to elegantly separate, collect and concentrate products that we require (nutrients) and those that we wish to regulate (pathogens and micropollutants). Since recent research efforts have been devoted to the technological recovery of nutrients from human urine, we believe that we are witnessing a paradigm shift within a paradigm shift as it represents a change in emphasis from ‘split-stream collection and reuse’ to ‘split-stream collection, resource recovery and safe reuse’. Our analysis of various nutrient recovery technologies for human urine indicates that provisioning of urine-diverting toilets tends to reduce sanitary risks; however, to contain and completely eliminate these risks continued research effort is needed to envision and implement integrated technological pathways that ensure simultaneous nutrient recovery, pathogen inactivation and reduction of pharmaceuticals and active substances. © 2016 Chinese Institute of Environmental Engineering, Taiwan

Fulltext

Sustainable Environment Research

Ecological Sanitation and nutrient recovery from human urine: How far have we come? A review

Despite its high concentration, potential availability and hence, potential reusability of nutrients, human urine continues to be flushed away in our toilets. The poor management of nutrients in our built environment in lieu of the representative failures in our systems to safely handle, treat and assimilate these 'waste' resources has resulted in considerable environmental externalities. Adsorption systems that utilize agro-waste sourced carbon as an adsorption media have shown promise in recovering plant-required nutrients from urine. This study details the applicability of two continuously operated columns for stripping urea from urine for subsequent use as fertilizers. The first column was packed with prepared carbon at various bed heights (10-50 cm) and the second column had carbon immobilized over etched glass beads of various support sizes (1.5-2.5 cm). By using a Box-Behnken design and Response Surface Methodology (RSM), the system was optimized with the objective of maximizing column capacities. For the packed bed, maximum sorption of 0.116 g.g-1 occurs at inlet flow rate of 6 L.h-1, concentration of 100% and carbon bed depth of 30 cm; in the immobilized bed, the optimal parameters were identified as flow rate of 10 L.h-1, 100% initial urea concentration and support size of 1.5 cm to yield capacity of 0.328 g.g-1. Immobilization as a pre-treatment in column design was significantly advantageous in recovering higher amount of urea at lesser activated carbon input relative to the packed bed. RSM was found to be an effective tool for selecting the process parametric inputs, in describing their effects on the operation of the column and in maximizing the urea recovery. © 2016 The Authors.

Procedia Engineering

Adsorptive Resource Recovery from Human Urine: System Design, Parametric Considerations and Response Surface Optimization

As a solution to the drawbacks of modern sanitation systems and to shift towards a recycling society, source separation of human wastes coupled with resource recovery could be seen as a potential solution. In this research, microwave activated coconut shells were utilized to recover urea from human urine. Batch adsorption studies were carried out to determine the effect of initial concentration, adsorption temperature, microwave output power and irradiation time on the urea uptake capacity of the tailored activated carbon. The shells pretreated with microwave irradiation of 360 W, for 15 min (MACCS-360W-15) shown to be promising adsorbents with BET surface area &gt;1000 m2 g-1. The sorption data were tested against different isotherm models and found to closely follow Langmuir isotherm with a maximum monolayer sorption capacity of 312 mg g-1. Kinetic data over temperature range of 30-60 °C was found to closely follow pseudo-first-order at all adsorbate concentrations. Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) indicated the spontaneity and physical nature of the sorption; sorption experiments indicated a urea recovery of ~95% from urine. Finally, the application of urea adsorbed carbon as a soil conditioner in field trials resulted in significant improvement in the number of seed germination and plant biomass (132%) with a substantial increase in the soil nitrogen and cation exchange capacity. Results also indicated that nearly all the urea was desorbed within the soil during irrigation becoming readily available to the plants. This study demonstrates a closed-loop sanitation cycle that channels nutrients from human beings back to agricultural fields. © 2015 The Institution of Chemical Engineers.

Closed-loop fertility cycle: Realizing sustainability in sanitation and agricultural production through the design and implementation of nutrient recovery systems for human urine

Microwave Activated Carbonized Coconut Shell (MACCS) was used to recover urea from human urine. Batch adsorption studies were conducted to evaluate the effect of initial adsorbate concentration (25%-100%), contact time, carbon loading (1-3 g) and shaking speed (150-200 rpm) on the removal of urea at 30 C. Microwave activation was performed at 180 W (microwave output power) for 10 min. The sorption data were fitted to Langmuir, Freundlich, Tempkin, Flory-Huggins and Dubinin-Radushkevich isotherm models. Results showed that the maximum monolayer adsorption capacity of the MACCS powder was 256.41 mg g-1. The Flory-Huggins model was found to best describe the urea uptake process since it demonstrated the minimum deviations from the experimental data. The kinetic data was fitted to pseudo-first-order, pseudo-second-order and intra-particle diffusion models, and was found to follow closely the pseudo-first order kinetic model. Based on the Central Composite Rotary Design, a five factor interaction model and a quadratic model were respectively developed to correlate the adsorption variables to the adsorption capacity. Field studies were conducted to determine the percentage biomass increase and relative agronomic effectiveness for soil treated with the urea adsorbed MACCS powder. Microwave activated carbonized coconut shell was shown to be a promising adsorbent for recovery and removal of urea from human urine solutions. © 2013 Elsevier Ltd.

Journal of Environmental Chemical Engineering

Recovering urea from human urine by bio-sorption onto Microwave Activated Carbonized Coconut Shells: Equilibrium, kinetics, optimization and field studies

Journal	Data powered by TypesetSustainable Production and Consumption
Publisher	Data powered by TypesetElsevier BV
ISSN	2352-5509
Open Access	0