Suitability of the Decentralised Wastewater Treatment Effluent for Agricultural Use: Decision Support System Approach

Musazura, William; Odindo, Alfred

doi:10.3390/w13182454

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…The results of several field trials have been documented for a variety of crops (Musazura et al, 2015;Odindo et al, 2016). However, a recent study by Musazura and Odindo (2021) highlighted that the high nutrient loading in the AF effluent can result in delayed flowering and uneven ripening for maize crops, while pathogen (Escherichia coli) contamination was possible with overhead irrigation of leafy vegetables such as cabbage and lettuce. The authors recommended dilution of the AF effluent or further treatment to deactivate the pathogens which may be present (Musazura and Odindo, 2021).…”

Section: Introductionmentioning

confidence: 99%

The potential of decentralised wastewater treatment in urban and rural sanitation in South Africa: lessons learnt from a demonstration-scale DEWATS within the eThekwini Municipality

Arumugam¹,

Zuma²,

Mercer³

et al. 2023

WSA

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The design principles of decentralised wastewater treatment systems (DEWATS) make them a practical sanitation option for municipalities to adopt in fast-growing cities in South Africa. Since 2014, a demonstration-scale DEWATS with a modular design consisting of a settler, anaerobic baffled reactor (ABR), anaerobic filter (AF), vertical down-flow constructed wetland (VFCW) and horizontal flow constructed wetland (HFCW) has been in operation in eThekwini. A performance evaluation after the long-term operation was undertaken in 2019 by comparing the final effluent with national regulatory requirements. Despite limitations in characterising the raw wastewater, a comparison of the settler and final effluent quality indicated high (≥ 85%) removal efficiencies of total chemical oxygen demand (CODt), ammonium-N (NH4-N) and orthophosphate-P (PO4-P), 75% removal of total suspended solids (TSS) and 83.3% log10 removal of Escherichia coli. Lack of exogenous and endogenous carbon and high dissolved oxygen (DO) concentrations (> 0.5 mg‧L−1) inhibited denitrification in the HFCW, resulting in 12.5% of the effluent samples achieving compliance for nitrate-N (NO3-N). Moreover, mixed aggregate media and low residence times in the HFCW may have also contributed to poor NO3-N removal. During the COVID-19 lockdown, an unexpected shutdown and subsequent resumption of flow to the DEWATS indicated a 16-week recovery time based on achieving full nitrification in the HFCW. Although design modifications are necessary for the HFCW, the installation of urine diversion flushing toilets at the household will reduce the nutrient loading to the DEWATS and potentially achieve fully compliant effluent. Alternatively, the application of two-stage vertical flow constructed wetlands to improve denitrification should also be explored in the South African context. With an improved design, DEWATS has the potential to fill the gap in both urban and rural sanitation in South Africa, where waterborne sanitation is still desired but connections to conventional wastewater treatment works (WWTWs) are not possible.

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Section: Introductionmentioning

confidence: 99%

The potential of decentralised wastewater treatment in urban and rural sanitation in South Africa: lessons learnt from a demonstration-scale DEWATS within the eThekwini Municipality

Arumugam¹,

Zuma²,

Mercer³

et al. 2023

WSA

View full text Add to dashboard Cite

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Suitability of the Decentralised Wastewater Treatment Effluent for Agricultural Use: Decision Support System Approach

Musazura

Odindo

2021

Water

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The decentralised wastewater treatment system (DEWATS) is an onsite sanitation technology that can be used in areas away from municipal sewerage networks. The discharge of effluent emanating from DEWATS into water bodies may cause pollution. Agricultural use of the effluent may improve crop yields and quality thereby contributing to food security in low-income communities. There are drawbacks to the agricultural use of treated wastewater. Therefore, the study assessed the crop, environmental and health risks when irrigating with anaerobic filter (AF) effluent using the Decision Support System (DSS) of the South African Water Quality Guideline model, in four South African agroecological regions, three soil types, two irrigation systems and three different crops. The model was parameterised using AF effluent characterisation data and simulated for 45 years. The model predicted that there are no negative impacts for using AF effluent on soil quality parameters (root zone salinity, soil permeability and oxidisable carbon loading), leaf scorching and irrigation equipment. The problems were reported for nutrient loading (N and P) in maize and microbial contamination in cabbage and lettuce. It was recommended that the effluent should be diluted when used for maize production and advanced treatment should be explored to allow unrestricted agricultural use.

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Suitability of the Decentralised Wastewater Treatment Effluent for Agricultural Use: Decision Support System Approach

Cited by 2 publications

References 23 publications

The potential of decentralised wastewater treatment in urban and rural sanitation in South Africa: lessons learnt from a demonstration-scale DEWATS within the eThekwini Municipality

The potential of decentralised wastewater treatment in urban and rural sanitation in South Africa: lessons learnt from a demonstration-scale DEWATS within the eThekwini Municipality

Suitability of the Decentralised Wastewater Treatment Effluent for Agricultural Use: Decision Support System Approach

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