scholarly journals Overview of Biological Treatment Technologies for Greywater Reuse

2021 ◽  
Vol 5 (3) ◽  
Keyword(s):  
Biological Treatment ◽  
Agricultural Land ◽  
Batch Reactor ◽  
Low Cost ◽  
Domestic Wastewater ◽  
Water Shortage ◽  
Anaerobic Sludge ◽  
Illegal Migration ◽  
Residual Concentration ◽  
Global Water

Greywater is a wastewater discharge originating from kitchen sinks, showers, baths, washing machines and dishwashers. Properly treated greywater can be recycled to meet global water shortages that is expected to affect 2.7 billion people around the world by 2025. Global water shortage can result in a reduction in agricultural land and increased dissertation leading to poverty, faming, war, illegal migration and human trafficking. Greywater contains fewer pathogens than domestic wastewater, is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape and crop irrigation. Recycling of grey water provides substantial benefits for both the water supply system by reducing the demand for fresh clean water, and for the wastewater system by reducing the amount of wastewater required to be conveyed and disposed of. In this paper, the existing biological treatment systems for greywater are reviewed. These are: (a) constructed wet land, (b) sequencing batch reactor, (c) vertical flow bioreactor, (d) membrane bioreactor, (e) up-flow anaerobic sludge blanket, (f) rotating biological contractors, (g) trickling filters, (h) aerated lagoons, (i) anaerobic up-flow filter, and (j) expanded bed up-floe reactor. In a biological treatment, the degradation and transformation of greywater constituents are facilitated by the biochemical reactions carried out by microorganisms in the liquid medium. However, the effluent of biologically treated greywater may contain pathogenic microorganisms, requiring a final disinfection step to eliminate the risk of contracting pathogenic diseases. Selection criteria for a disinfectant include: (a) non-toxicity to humans, domesticated animals, and aquatic ecosystems, (b) low cost (c) easy handling, (d) reliable analysis, and (e) a satisfactory residual concentration. Any disinfection process selected (whether chemical oxidants or irradiation treatment is selected) should be evaluated taken into consideration the conditions of the wastewater source and existing biological treatment design.

Deep-bed filtration of SBR effluent for agricultural reuse: pilot plant screening of advanced secondary and tertiary treatment for domestic wastewater

1994 ◽  
Vol 30 (9) ◽  
pp. 219-227 ◽  
Author(s):  
Asher Brenner ◽  
Semen Shandalov ◽  
Gideon Oron ◽  
Menahem Rebhun
Keyword(s):  
Batch Reactor ◽  
Groundwater Resources ◽  
Domestic Wastewater ◽  
Water Shortage ◽  
Pilot Scale ◽  
Treated Wastewater ◽  
Wastewater Reclamation ◽  
Tertiary Treatment ◽  
Granular Filtration ◽  
Single Medium

A wastewater reclamation program has been proposed as a means of supplying a major part of agricultural water demand in Israel. This program may solve the two fold problem of a national water shortage combined with continuous contamination of groundwater resources by inadequately treated wastewater. A pilot-scale investigation of an advanced treatment scheme incorporating a sequencing batch activated sludge system, followed by deep-bed granular filtration, has been started. It is aimed at the development of design and operation guidelines for such systems to be applied on a full scale. Preliminary results presented herein indicate that the sequencing batch reactor system is capable of producing high-quality, low-suspended-solids effluent to be further polished by granular filtration. A single medium quartz sand filter operated under a high variety of filtration velocities and inflow turbidities with no chemicals added, demonstrated good performance and supplied basic design information to be applied in further investigation.

Case studies on municipal wastewater reclamation and reuse in China

2003 ◽  
Vol 3 (3) ◽  
pp. 117-124
Author(s):  
B. Wang ◽  
L. Wang ◽  
G. Li ◽  
P. Qi ◽  
Y. Liu
Keyword(s):  
Municipal Wastewater ◽  
Low Cost ◽  
Water System ◽  
Domestic Wastewater ◽  
Water Shortage ◽  
Initial Energy ◽  
Wastewater Reclamation ◽  
Treatment Processes ◽  
Wastewater Reclamation And Reuse ◽  
Water Scarce

Water shortage and water environmental pollution have promoted the development of wastewater reclamation and reuse in China in recent years. Different treatment processes are employed for this purpose, such as pond-farmland systems using solar radiation as initial energy source, treating wastewater at low cost and low energy consumption to realize wastewater reclamation and reuse for irrigation on farmland to provide both water and nutrients. Some full-scale projects on municipal wastewater reclamation mainly based on activated sludge and/or submerged biofilm processes followed by some advanced treatment processes such as filtration and disinfecting, from which the effluent is reused in agriculture, industry and domestic uses except for drinking purpose have been built and put into operation in some water shortage cities, which are described in this paper. In some water scarce cities the domestic wastewater reclamation and reuse (dual water system) is employed for a building, a group of buildings or a sub-residential district, whose treatment system consists of submerged biofilm process, dual-media filter and disinfection.

Load limit of a UASB fed septic tank-treated domestic wastewater

2015 ◽  
Vol 72 (8) ◽  
pp. 1455-1461 ◽  
Author(s):  
Sunil Prasad Lohani ◽  
Rune Bakke ◽  
Sanjay N. Khanal
Keyword(s):  
Chemical Oxygen Demand ◽  
Low Cost ◽  
Scale Up ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Pilot Scale ◽  
Uasb Reactor ◽  
Septic Tank ◽  
Anaerobic Sludge ◽  
Combined System

Performance of a 250 L pilot-scale up-flow anaerobic sludge blanket (UASB) reactor, operated at ambient temperatures, fed septic tank effluents intermittently, was monitored for hydraulic retention time (HRT) from 18 h to 4 h. The total suspended solids (TSS), total chemical oxygen demand (CODT), dissolved chemical oxygen demand (CODdis) and suspended chemical oxygen demand (CODss) removal efficiencies ranged from 20 to 63%, 15 to 56%, 8 to 35% and 22 to 72%, respectively, for the HRT range tested. Above 60% TSS and 47% CODT removal were obtained in the combined septic tank and UASB process. The process established stable UASB treatment at HRT ≥ 6 h, indicating a hydraulic load design limit. The tested septic tank–UASB combined system can be a low-cost and effective on-site sanitation solution.

Biological treatment of saline domestic wastewater by using a down-flow hanging sponge reactor

Chemosphere ◽  
2021 ◽  
pp. 131101
Author(s):  
Dinh T. Nga ◽  
Nguyen T. Hiep ◽  
Arvind Kumar Mungray ◽  
La Duc Duong ◽  
Phuong Nguyen-Tri ◽  
...  
Keyword(s):  
Biological Treatment ◽  
Domestic Wastewater

scholarly journals Simultaneous Nitrification and Denitrification in an SBR with a Modified Cycle During Reject Water Treatment

2013 ◽  
Vol 39 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Katarzyna Bernat
Keyword(s):  
Batch Reactor ◽  
Anaerobic Sludge ◽  
Simultaneous Nitrification And Denitrification ◽  
Low Oxygen ◽  
Total Removal ◽  
Operational Conditions ◽  
Reject Water ◽  
Do Concentration ◽  
Nitrification And Denitrification ◽  
Low Oxygen Concentration

Abstract In this study, the dependence between volumetric exchange rate (n) in an SBR (Sequencing Batch Reactor) with a modified cycle and simultaneous nitrification and denitrification (SND) efficiency during the treatment of anaerobic sludge digester supernatant was determined. In the SBR cycle alternating three aeration phases (with limited dissolved oxygen (DO) concentration up to 0.7 mg O2/L) and two mixing phases were applied. The lengths of each aeration and mixing phases were 4 and 5.5 h, respectively. Independently of n, a total removal of ammonium was achieved. However, at n = 0.1 d-1 and n = 0.3 d-1 nitrates were the main product of nitrification, while at n = 0.5 d-1, both nitrates and nitrites occurred in the effluent. Under these operational conditions, despite low COD/N (ca. 4) ratio in the influent, denitrification in activated sludge was observed. A higher denitrification efficiency at n = 0.5 d-1 (51.3%) than at n = 0.1 d-1 (7.8%) indicated that n was a crucial factor influencing SND via nitrite and nitrate in the SBR with a low oxygen concentration in aeration phases.

Nitrite reduction and methanogenesis in a single-stage UASB reactor

2015 ◽  
Vol 72 (12) ◽  
pp. 2236-2242 ◽  
Author(s):  
L. I. Borges ◽  
C. M. López-Vazquez ◽  
H. García ◽  
J. B. van Lier
Keyword(s):  
Domestic Wastewater ◽  
High Strength ◽  
Single Stage ◽  
Nitrite Reduction ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
N Removal

In this study, nitrite reduction and methanogenesis in a single-stage upflow anaerobic sludge blanket (UASB) reactor was investigated, using high-strength synthetic domestic wastewater as substrate. To assess long-term effects and evaluate the mechanisms that allow successful nitrite reduction and methanogenesis in a single-stage UASB, sludge was exposed to relatively high nitrite loading rates (315 ± 13 mgNO2−-N/(l.d)), using a chemical oxygen demand (COD) to nitrogen ratio of 18 gCOD/gNO2−-N, and an organic loading rate of 5.4 ± 0.2 gCOD/(l.d). In parallel, the effects of sludge morphology on methanogenesis inhibition were studied by performing short-term batch activity tests at different COD/NO2−-N ratios with anaerobic sludge samples. In long-term tests, denitrification was practically complete and COD removal efficiency did not change significantly after nitrite addition. Furthermore, methane production only decreased by 13%, agreeing with the reducing equivalents requirement for complete NO2− reduction to N2. Apparently, the spatial separation of denitrification and methanogenesis zones inside the UASB reactor allowed nitrite reduction and methanogenesis to occur at the same moment. Batch tests showed that granules seem to protect methanogens from nitrite inhibition, probably due to transport limitations. Combined COD and N removal via nitrite in a single-stage UASB reactor could be a feasible technology to treat high-strength domestic wastewater.

Monitoring soil nutrients using a simple cafetiere-based extraction with paper-based readout. 

2021 ◽  
Author(s):  
Samantha Richardson ◽  
Samira Al Hinai ◽  
Jesse Gitaka ◽  
Will Mayes ◽  
Mark Lorch ◽  
...  
Keyword(s):  
Image Analysis ◽  
Incubation Period ◽  
Soil Nutrients ◽  
Agricultural Land ◽  
Low Cost ◽  
Smart Phone ◽  
Water Volume ◽  
Readout System ◽  
Paper Microfluidic ◽  
Nutrient Extraction

<p>Routine monitoring of available soil nutrients is required to better manage agricultural land<sup>1</sup>, especially in many lower and middle income countries (LMICs). Analysis often still relies on laboratory-based equipment, meaning regular monitoring is challenging.<sup>2</sup> The limited number of in situ sensors that exist are expensive or have complex workflows, thus are not suitable in LMICs, where the need is greatest.<sup>3</sup> We aim to develop a simple-to-use, low-cost analysis system that enable farmers to directly monitor available nutrients and pH on-site, thus making informed decisions about when and where to apply fertilisers.</p><p>We combine nutrient extraction via a cafetiere-based filtration system with nutrient readout on a paper microfluidic analysis device (PAD) employing colour producing reactions that can be captured via a smartphone camera through an app. Image analysis of colour intensity permits quantitation of analytes. We initially focus on key nutrients (phosphate, nitrate) and pH analysis.</p><p>For extraction of phosphate, we mixed soil and water in the cafetiere and quantified the extracted phosphate via phosphomolybdenum blue chemistry. For example, for 5 g of soil, a water volume of about 160 mL led to optimum extraction. Active mixing, by pushing coffee filter plunger up and down, aided extraction. A mixing period of 3 min yielded maximum extraction; this time period was deemed suitable for an on-site workflow.</p><p>Following nutrient extraction, a simple-to-use readout system is required. For this, we developed colourimetric paper-based microfluidic devices; these are simply dipped into the decanted soil supernatant from the cafetiere and wick fluids based on capillary forces. Chemical reagents are pre-stored in reaction zones, created by patterning cellulose with wax barriers. Our devices contain multiple paper layers with different reagents; these are folded, laminated and holes cut for sample entry. Following the required incubation time, the developed colour is captured using a smartphone. This constitutes a portable detector, already available to envisaged end users, even in LMICs. We have previously developed an on-paper reaction for monitoring phosphates in fresh water in the mg L<sup>-1</sup> working range, with readout after an incubation period of 3 min. This method was adapted here to enable storage at ambient temperatures up to 1 week by incorporating additional acidic reagents. Further pad devices were developed in our group for colour-based readout of nitrate, involving a two-step reaction chemistry. Within a relatively short incubation period (≤8 min) a pink coloured was formed following reduction of nitrate to nitrite with zinc and subsequent reaction to form an azo-dye. This system achieved detection in the low mg L<sup>-1</sup> range. Moreover, a pad to monitor pH was developed, employing chlorophenol red indicator, with linear response achieved over the relevant pH 5-7 range.  </p><p>Our analysis workflow combines a simple-to-use cafetiere-based extraction method with paper microfluidic colour readout and smart-phone detector. This has the potential to enable farmers to monitor nutrients in soils on-site. Future work will aim at integrating multiple analytes into a single analysis card and to automate image analysis.</p><p>[1] <em>Europ. J. Agronomy</em>, 55, 42–52, <strong>2014.</strong></p><p>[2] <em>Nutr. Cycling Agroecosyst.,</em> 109, 77-102, <strong>2017.</strong></p><p>[3] Sens Actuators B, 30, 126855, <strong>2019.</strong></p>

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