In-Situ Treatment Technologies

Abstract The capture and re-use of greenhouse fertigation water is an efficient use of fertilizer and limited water resources, although the practice is not without risk. Plant pathogens and chemical contaminants can build up over successive capture and re-use cycles; if not properly managed they can lead to reduced productivity or crop loss. There are numerous established and emerging water treatment technologies available to treat fertigation water. Electrochemical processes are emerging as effective means for controlling pathogens via in situ regenerative hypochlorination; a process that is demonstrated here to achieve pathogen control in fertigation solutions without leading to the accumulation of potentially phytotoxic free chlorine residuals associated with other chlorination processes. An electrochemical flow cell (EFC) outfitted with ruthenium dioxide (RuO2) dimensionally stable anodes (DSA) was characterized and evaluated for free chlorine production and Rhizoctonia solani inactivation in both irrigation and fertigation solutions. Pathogen inactivation was achieved at low current densities and short residence or cell contact times. Effluent free chlorine concentrations were significantly lower than commonly reported phytotoxic threshold values (approximately 2.5 mg/L) when fertilizer (containing ammonium) was present in the test solution; an effect attributable to reactions associated with breakpoint chlorination, including chloramine formation, as well as the presence of other oxidizable compounds in the fertilizer. Chloride concentrations were stable under the test conditions suggesting that the EFC was operating as a regenerative in situ electrochemical hypochlorination system. No significant changes to macronutrient concentrations were found following passage through the EFC.

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Isolation and degradation characteristics of bacteria in black and odorous water

Water Science & Technology Water Supply ◽

10.2166/ws.2021.057 ◽

2021 ◽

Author(s):

Hao Yuan ◽

Gangcai Chen ◽

Yuchun Xiao ◽

Jianxia Yang ◽

Liping Huang ◽

...

Keyword(s):

Oxygen Demand ◽

Volume Ratio ◽

Ammonia Nitrogen ◽

Overlying Water ◽

Bacterial Agent ◽

Functional Bacteria ◽

Final Compound ◽

Treatment Technologies ◽

Optimized Conditions

Abstract Bioremediation is one of the treatment technologies for the black-odorous water, and obtaining functional bacteria is the key step to its success. In this study, a number of highly efficient pollutant degrading strains were isolated from the sediment of black-odorous river, and were identified by phenotypic and phylogenetic analysis. The composite bacterial agent J1 was mixed by strains A1, A2, A5 and A7, with a volume ratio of 4:4:2:1. And the final compound bacteria injected into black-odorous water were composed of J1 and NS3, with the volume ratio of 1:1. Optimized degradation conditions of compound bacterium agent were as follows: pH 7.5, DO 2.5 mg/L, temperature 30 °C. Under optimized conditions, add 1% by volume to the black-odorous water for a 50-day experimental operation. Finally, the overlying water ammonia nitrogen, chemical oxygen demand (COD), and total phosphorus has been significantly degraded. The research is expected to contribute to the use of bioremediation methods to repair black-odorous water, and the application of isolates can be carried out in-situ for water types similar to pollute waterways.

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In situ treatment technologies for pit latrines to mitigate groundwater contamination by fecal pathogens: a review of recent technical advances

Journal of Water Sanitation and Hygiene for Development ◽

10.2166/washdev.2021.184 ◽

2021 ◽

Author(s):

Shray Saxena ◽

Walter Den

Keyword(s):

Early Stage ◽

Appropriate Technology ◽

Permeable Reactive Barriers ◽

Fecal Sludge ◽

Technical Advances ◽

Fecal Pathogens ◽

Treatment Technologies ◽

Sanitation Systems ◽

The Impact

Abstract On-site sanitation systems such as pit latrines are extensively used around the world, while there is a growing number of evidence documenting the impact of pit latrines on groundwater quality that may affect human health. Hence, this paper summarizes the various safe-sanitation technologies by broadly categorizing them into fecal pathogen disinfection methods (anaerobic digestion, chemical disinfection, biological additives, solar pasteurization and vermicomposting) and capturing methods (pit lining and permeable reactive barriers, the latter of which simultaneously capture and sanitize fecal sludge in pit latrines). While some of the reviewed technologies have been widely practiced for mitigating microbial contamination of the groundwater, others are still in the early stage of commercialization and field validation. Though there are challenges to the selection and adoption of the most appropriate technology, this paper discusses the readiness of each technology as a stand-alone fecal sludge management solution.

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A new photo-activated sludge system for nitrification by an algal-bacterial consortium in a photo-bioreactor with biomass recycle

Water Science & Technology ◽

10.2166/wst.2015.205 ◽

2015 ◽

Vol 72 (3) ◽

pp. 443-450 ◽

Cited By ~ 11

Author(s):

Peter van der Steen ◽

Kuntarini Rahsilawati ◽

Angélica M. Rada-Ariza ◽

Carlos M. Lopez-Vazquez ◽

Piet N. L. Lens

Keyword(s):

Growth Rate ◽

Activated Sludge ◽

Energy Savings ◽

New Technology ◽

Bacterial Consortium ◽

Continuous Illumination ◽

Treatment Technologies ◽

Photo Bioreactor ◽

Activated Sludge Systems

Wastewater treatment technologies requiring large areas may be less feasible in urbanizing regions of developing countries. Therefore, a new technology, named photo-activated sludge (PAS), was investigated to combine the advantages of regular activated sludge systems with those of algae ponds for the removal of ammonium. The PAS consisted of a mixed photo-bioreactor, continuously fed with BG-11 medium, adjusted to 66 mgN-NH4+/l. The reactor volume was 2 l, hydraulic retention time was 24 hours, with a depth of 8 cm, and continuous illumination at the water surface was 66 μmol PAR/m2/s (photosynthetically active radiation). Reactor effluent passed through a settler and settled biomass was returned to the reactor. A well settling biomass developed, that contained both algae and nitrifiers. Effluent contained 10 mgN-NH4+/L and 51 mgN-NOx−/L. Using a simplified model, the specific algae growth rate was estimated at about 0.62 day−1, which was within the expected range. For nitrifiers (ammonia oxidizers), the specific growth rate was 0.11 day−1, which was lower than reported for regular activated sludge. The in-situ photo-oxygenation process by algae contributed 82% of the oxygen input, whereas oxygen diffusion through the mixed surface provided the remaining 18%. The foreseen energy savings that a PAS system could achieve warrant further investigations with real wastewater.

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