# Experience of Application of Natural Treatment Systems for Wastewater (NTSW) in Livestock Farms in Canary Islands

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## Abstract

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## 1. Introduction

## 2. Materials and Methods

#### 2.1. Pilot Plants Features

**Plant 1.**Farm located at 450 m of altitude (UTM coordinates x: 450,052.41 m, y: 3,105,359.68 m), with 1600 animals. The effluent from the farm (13.60 m${}^{3}$/day) is discharged to a holding tank, which has been fitted with a 10 micron rotary screen and it is deposited in a pond of $length/wide$, $2/1$ and 1100 m${}^{3}$ of effective capacity. The depth is 1.5 m. Figure 5 displays a photograph of Plant 1, with a detail of the pond. The total hydraulic retention time $\left(HRT\right)$ is 80 days.**Plant 2.**Farm located at 540 m above sea level (UTM coordinates x: 443,504.65 m, y: 3,105,955 m), with 1100 animals. The effluent (6.40 m${}^{3}$/day) is conveyed in the retention tank. In the holding tank (capacity 40 m${}^{3}$, and retention time 4–6 days), it will be stored the manure until it is sieved. At the top of the half-closed closed digester is a 100-micron mesh rotary screen. The dimensions of the rectangular half-buried digester are 17.50 m × 6.50 m × 3.50 m and an effective height of 1.70 m. It is constituted by six rectangular chambers of dimensions 3.00 m × 3.00 m, being of all them equal and intercommunicated by siphon, with an effective capacity unit of 22.90 m${}^{3}$ each, and 132.60 m${}^{3}$ of total volume. By the type of flow, it is possible to assimilate it to the operation of a cascade digester. Figure 6 displays a photograph of Plant 2, with a detail of the rotary screen, and the anaerobic digesters. The $HRT$ is 25 days.**Plant 3.**Farm located at 700 m of altitude (UTM coordinates x: 446,164 m, y: 3,102,557.64 m 28${}^{\circ}$2.83${}^{\prime}$ N, 15${}^{\circ}$32.87${}^{\prime}$ W), with 1400 animals. Effluent (8.70 m${}^{3}$/day) is collected in a reception tank with a capacity of 10 m${}^{3}$, then it is taken to the chamber 1 of an anaerobic digester. In the**chamber 1**, the slurry is stored until it is pumped to the 100 micron rotary screen on top of the anaerobic digester. The rectangular anaerobic digester consists of four equal and interconnected rectangular chambers with an effective capacity of 103.00 m${}^{3}$ in total and $HRT$ of 10 days. At the exit of the digester, the waste past to the first of the constructed wetlands with subsurface vertical flow $\left(SVSFCW\right)$ constituted by a cubicle with rectangular form, this volume is filled by stones of varied granulometry, being the free volume 22.95 m${}^{3}$ and a $HRT$ about of 4 days. In the subsurface constructed wetland $SSFCW$ several types of plants are developed that degrade the organic matter. It has two vertical ventilation tubes. The passage of the water to be treated is performed below the surface throughout the lateral contact area with the pond. Slurry from $SSFCW\phantom{\rule{4pt}{0ex}}1$ flows into a pond of $length/width$ ratio, $2/1$ and 90 m${}^{3}$ of effective capacity. The depth will be 1.5 m. The residence time is 10 days.The pond is surrounded by constructed wetlands, this has allowed us to experiment with a pond of inferior capacity and on the plant 1. The $SVFCW\phantom{\rule{4pt}{0ex}}2$, at the outlet of the effluent, has an identical design to the previous one. The installation has a recirculation circuit that allows recirculating of all or part of the liquid that exists in the lagoon to a control pool that is connected to the homogenization tank. At the end of $SVFCW\phantom{\rule{4pt}{0ex}}2$, it is the final tank of dimensions of 10.50 m${}^{3}$ of capacity. The stabilized effluent percolates from the wetland to the final tank. Figure 6 displays a photograph of Plant 3, with a detail of the pond, and the constructed wetlands. The $HRT$ is 28 days.

- Each chamber of the digesters and ponds were initially filled with clean water.
- No external resources have been added, such as bacteria cultures, sewage sludge, etc., leaving only the slurry to rest so that the native bacterial flora develops its performance.

#### 2.2. Parameters and Samples

- During the first half of the year, the samples were taken four times a month, equally spaced in time.
- In the second half of the year, the samples were taken twice a month, equally spaced in time.
- After the first year, samples were taken on a monthly basis.

**Standard and Methods (APHA 2005)**. Each plant has a meteorological station with measurement of; ambient temperature ${T}_{A}$, humidity $\varphi $, and rainfall ${R}_{acc}$. For the statistical analysis of the data, the $COD$ has been set as the central variable so that this variable can be compared with the rest to be able to observe possible correlations. On the data set, under the approach of finding relationships between the parameters of the waste in the sampling point in each one of the digesters chamber and ponds, it was attempted to demonstrate that the variations of $COD$ during the weeks, it was related to the variation of $pH$ or $EC$ at that same sampling point. When the homoscedasticity tests were carried out, which are a fundamental requirement for good factor analysis, it was not found any relationships between parameters at the point of sampling in each of the chambers and lagoons, and in consequence no significant correlation was going to be obtained from this hypothesis. Therefore, another approach to the data was sought, and it was decided to analyze the behavior of the installation during the complete cycle, in which the slurry passes through the plant, defined by the Global Hydraulic Retention Time for the plant ($HR{T}_{G}$) of 82, 27 and 27 days (plant 1, 2 and 3, respectively). The initial hypothesis is established, that it is possible to relate punctual data of parameters with their respective evolution at the outlet, after the days of the treatment cycle. From the 131 samples available, for the three plants, we selected 30, 21 and 21 sampling data from the 131 available samples, making the grouping of the corresponding values of the study parameters possible.

## 3. Results and Discussions

#### 3.1. Atmospheric Conditions

#### 3.2. Temporal Evolution of the Analyzed Variables

- The curves of variables, which are labeled $EF$, for plants 1 and 2, and subindex $C{h}_{1}$, for plant 3, represent the discharge in the pilot plants of the pools and intermediate tanks that each of the livestock farms have in their pens.
- The curves of variables, which its label has the subindex $EP$, for plant 1, and subindex $C{h}_{1}$, for plant 2, and subindex $C{h}_{2}$, for plant 3, represent the initial point of the system.
- An finally, the curves of variables, which its label has the subindex $TE$, for plants 1 and 3, and subindex $C{h}_{6}$, for plant 2, represent the effluent treated of the plants.

#### 3.3. Correlations

#### 3.4. Performance

## 4. Conclussions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

$COD$ | Chemical oxigen demand |

$CO{D}_{EF}$ | Effluent farm $COD$ |

$CO{D}_{EP}$ | $COD$ of Effluent pond |

$CO{D}_{TE}$ | $COD$ of Treated Effluent |

$CO{D}_{C{h}_{i}}$ | $COD$ of chamber number i |

$CO{D}_{BP}$ | $COD$ at bottom of pond |

$CO{D}_{RE}$ | Percentage ratio of the removal efficiency of Chemical oxigen demand |

$CO{D}_{REG}$ | $CO{D}_{RE}$ of the global plant |

$CO{D}_{RES}$ | $CO{D}_{RE}$ at the screen |

$CO{D}_{RED}$ | $CO{D}_{RE}$ at the digester |

$CO{D}_{REEP}$ | $CO{D}_{RE}$ at the effluent pond |

$EC$ | Electrical conductivity |

$E{C}_{EF}$ | Effluent farm $EC$ |

$E{C}_{EP}$ | $EC$ at Effluent pond |

$E{C}_{EF}$ | $EC$ of the treated effluent |

$E{C}_{C{h}_{i}}$ | $EC$ at chamber number i |

$E{C}_{BP}$ | $EC$ at bottom of pond |

$E{C}_{RE}$ | Percentage ratio of the removal efficiency of electrical conductivity |

$E{C}_{REG}$ | $E{C}_{RE}$ of the global plant |

$E{C}_{REP}$ | $E{C}_{RE}$ of the pond |

$E{C}_{RES}$ | $E{C}_{RE}$ of the screen |

$E{C}_{RED}$ | $E{C}_{RE}$ of the digesters |

$HRT$ | Hydraulic retention time |

$HR{T}_{G}$ | Global Hydraulic retention time for the plant |

$NTSW$ | Natural treatment system for wastewater |

${N}_{Br}$ | Number of bristles |

${N}_{T}$ | Total number of animals |

$pH$ | Measure of the concentration of protons $\left[{\mathbf{H}}^{+}\right]$ in a solution |

$p{H}_{EF}$ | $pH$ at effluent farm |

$p{H}_{SP}$ | $pH$ at the surface pond |

$p{H}_{D}$ | $pH$ at the digester |

$p{H}_{C{h}_{i}}$ | $pH$ at chamber number i |

$p{H}_{G}$ | $pH$ of the global plant |

${\overline{pH}}_{G}$ | Average $pH$ of the global plant |

${\overline{pH}}_{D}$ | Average $pH$ of the digester |

${\overline{pH}}_{SP}$ | Average $pH$ at the surface pond |

${\overline{pH}}_{EF}$ | Average $pH$ at effluent farm |

${Q}_{eff}$ | Effluent flow rate |

${R}_{acc}$ | Accumulated rainfall |

${\overline{R}}_{acc}$ | Average accumulated rainfall |

$SSFCW$ | Subsurface flow constructed wetland |

${T}_{SP}$ | Temperature surface pond |

${T}_{A}$ | Ambient temperature |

${T}_{C{h}_{i}}$ | Indoor temperature chamber number i |

${\overline{T}}_{SP}$ | Average temperature surface pond |

${\overline{T}}_{A}$ | Average ambient temperature |

${\overline{T}}_{D}$ | Average digester temperature |

${V}_{RT}$ | Reception tank volume |

${V}_{AD}$ | Anaerobic digester volume |

${V}_{SSFCW}$ | SSFCW volume |

${V}_{P}$ | Pond volume |

$\varphi $ | Relative humidity |

$\overline{\varphi}$ | Average relative humidity |

## Appendix A. Samples for the Plants

Plant 1 | Plant 2 | Plant 3 | ||||||
---|---|---|---|---|---|---|---|---|

Monthly day | Time (day) | Sample | Monthly day | Time (day) | Sample | Monthly day | Time (day) | Sample |

June 27 | 0 | 1 | June 4 | 0 | 1 | July 4 | 0 | 1 |

July 13 | 16 | 2 | July 4 | 30 | 2 | August 3 | 30 | 2 |

July 30 | 43 | 3 | August 6 | 62 | 3 | August 14 | 41 | 3 |

August 18 | 61 | 4 | August 14 | 70 | 4 | October 2 | 89 | 4 |

September 18 | 92 | 5 | September 12 | 98 | 5 | October 30 | 117 | 5 |

October 4 | 108 | 6 | October 6 | 122 | 6 | Nobember 29 | 146 | 6 |

October 10 | 124 | 7 | October 11 | 127 | 7 | January 14 | 192 | 7 |

November 16 | 150 | 8 | January 31 | 237 | 8 | February 2 | 210 | 8 |

December 7 | 170 | 9 | February 7 | 244 | 9 | February 8 | 216 | 9 |

December 18 | 181 | 10 | February 14 | 251 | 10 | February 13 | 222 | 10 |

January 2 | 195 | 11 | February 22 | 259 | 11 | February 20 | 229 | 11 |

January 10 | 203 | 12 | March 6 | 273 | 12 | March 19 | 258 | 12 |

January 17 | 210 | 13 | March 17 | 284 | 13 | April 3 | 272 | 13 |

February 3 | 225 | 14 | March 31 | 298 | 14 | April 16 | 285 | 14 |

February 20 | 242 | 15 | April 17 | 315 | 15 | April 30 | 299 | 15 |

March 3 | 255 | 16 | April 30 | 328 | 16 | May 15 | 314 | 16 |

March 12 | 264 | 17 | May 14 | 342 | 17 | June 15 | 344 | 17 |

March 19 | 271 | 18 | June 3 | 361 | 18 | July 15 | 374 | 18 |

March 25 | 277 | 19 | June 25 | 383 | 19 | September 17 | 436 | 19 |

April 5 | 287 | 20 | September 17 | 465 | 20 | October 3 | 452 | 20 |

April 12 | 294 | 21 | November 4 | 512 | 21 | Nobember 4 | 483 | 21 |

April 23 | 305 | 22 | ||||||

May 17 | 329 | 23 | ||||||

May 25 | 337 | 24 | ||||||

June 23 | 365 | 25 | ||||||

July 7 | 379 | 26 | ||||||

August 03 | 405 | 27 | ||||||

August 24 | 426 | 28 | ||||||

September 17 | 449 | 29 | ||||||

October 18 | 479 | 30 |

## Appendix B. Rainfall, Relative Humidity and pH Results

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Plant | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{EF}}\\ \left(\mathbf{mg}/\mathbf{L}\right)\end{array}$ | $\begin{array}{c}{\mathbf{Q}}_{\mathbf{eff}}\\ \left({\mathbf{m}}^{3}/\mathbf{day}\right)\end{array}$ | ${\mathbf{N}}_{\mathbf{Br}}-{\mathbf{N}}_{\mathbf{T}}$ | $\begin{array}{c}{\mathbf{V}}_{\mathbf{RT}}-\mathbf{HRT}\phantom{\rule{0ex}{0ex}}\left({\mathbf{m}}^{3}\right)-\left(\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{V}}_{\mathbf{AD}}-\mathbf{HRT}\phantom{\rule{0ex}{0ex}}\left({\mathbf{m}}^{3}\right)-\left(\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{V}}_{\mathbf{SSFCW}}-\mathbf{HRT}\phantom{\rule{0ex}{0ex}}\left({\mathbf{m}}^{3}\right)-\left(\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{V}}_{\mathbf{P}}-\mathbf{HRT}\phantom{\rule{0ex}{0ex}}\left({\mathbf{m}}^{3}\right)-\left(\mathbf{day}\right)\end{array}$ |
---|---|---|---|---|---|---|---|

1 | 45,600 | $13.60$ | $\left(180\right)-\left(1890\right)$ | $\left(10\right)-\left(1\right)$ | − | − | $\left(1100\right)-\left(80\right)$ |

2 | 29,000 | $6.40$ | $\left(115\right)-\left(1068\right)$ | $\left(40\right)-\left(4\right)$ | $\left(132\right)-\left(21\right)$ | − | − |

3 | 50,000 | $8.70$ | $\left(160\right)-\left(1432\right)$ | $\left(10\right)-\left(1\right)$ | $\left(104\right)-\left(11\right)$ | $\left(46\right)-\left(5\right)$ | $\left(90\right)-\left(10\right)$ |

Plant | $\begin{array}{c}\mathbf{Total}\phantom{\rule{4pt}{0ex}}\mathbf{Capacity}\\ \left({\mathbf{m}}^{\mathbf{3}}\right)\end{array}$ | $\begin{array}{c}\mathbf{Occupied}\phantom{\rule{4pt}{0ex}}\mathbf{Surface}\\ \left({\mathbf{m}}^{\mathbf{2}}\right)\end{array}$ | $\begin{array}{c}\mathbf{HRT}\phantom{\rule{4pt}{0ex}}\mathbf{Global}\\ \left(\mathbf{day}\right)\end{array}$ | ||||

1 | 1115 | 750 | 81 | ||||

2 | 172 | 180 | 25 | ||||

3 | 250 | 140 | 27 |

Plant 1 | |

R${}^{2}$ | Correlation |

$0.866$ | ${COD}_{REG}=43.2947+70.5771\xb7{COD}_{REEP}^{2}-8.781\xb7{COD}_{REEP}^{3}$ |

$0.500$ | ${EC}_{REG}=19.202-0.097\xb7{R}_{acc}+0.002\xb7{R}_{acc}^{2}-1.488\times {10}^{-5}\xb7{R}_{acc}^{3}$ |

$0.798$ | ${EC}_{REG}=18.250-0.60\xb7{EC}_{REP}+0.020\xb7{EC}_{REP}^{2}+38.87\times {10}^{-5}\xb7{COD}_{REP}^{3}$ |

Plant 2 | |

R${}^{2}$ | Correlation |

$0.942$ | ${COD}_{REG}=5.923+0.437\xb7{EC}_{RED}+0.0161\xb7{EC}_{RED}^{2}-0.001\xb7{EC}_{RED}^{3}$ |

$0.602$ | ${EC}_{REG}=7.213+1.023\xb7{EC}_{RES}+0.135\xb7{EC}_{RES}^{2}-0.006\xb7{EC}_{RES}^{3}$ |

$0.847$ | ${EC}_{REG}=5.923+0.437\xb7{EC}_{RED}+0.061\xb7{EC}_{RED}^{2}-0.001\xb7{COD}_{RED}^{3}$ |

Plant 3 | |

R${}^{2}$ | Correlation |

$0.748$ | ${COD}_{REG}=92.559-1.087\xb7{EC}_{REP}+0.0501\xb7{EC}_{REP}^{2}-0.001\xb7{EC}_{REP}^{3}$ |

$0.769$ | ${EC}_{REG}=19.854-0.759\xb7{EC}_{REP}+0.063\xb7{EC}_{REP}^{2}-0.001\xb7{EC}_{REP}^{3}$ |

$0.426$ | ${EC}_{REG}=18.824-20.123\xb7{R}_{acc}-6.424\xb7{R}_{acc}^{2}-0.824\xb7{R}_{acc}^{3}$ |

Plant | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{RES}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{RED}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{REP}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{REG}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{RES}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{REP}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{RED}}\\ (\%)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{REG}}\\ (\%)\end{array}$ |
---|---|---|---|---|---|---|---|---|

1 | $18.08$ | − | $66.67$ | $72.64$ | $9.56$ | $19.37$ | − | $27.63$ |

2 | $14.63$ | $75.92$ | − | $79.75$ | $7.78$ | − | $12.94$ | $19.41$ |

3 | $15.41$ | $46.86$ | $66.27$ | $90.42$ | $8.31$ | $30.79$ | $5.41$ | $36.26$ |

Plant | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{RES}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{RED}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{REP}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{REG}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{RES}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{REP}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{RED}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{REG}}\\ (\%/{\mathbf{m}}^{\mathbf{3}})\end{array}$ |

1 | $1.291$ | − | $0.061$ | $0.065$ | $0.683$ | $0.018$ | − | $0.025$ |

2 | $0.366$ | $0.575$ | − | $0.464$ | $0.195$ | − | $0.091$ | $0.107$ |

3 | $4.541$ | $0.455$ | $0.488$ | $0.377$ | $0.831$ | $0.342$ | $0.053$ | $0.146$ |

Plant | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{RES}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{RED}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{REP}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{COD}}_{\mathbf{REG}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{RES}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{REP}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{RED}}\\ \left(\%/\mathbf{day}\right)\end{array}$ | $\begin{array}{c}{\mathbf{EC}}_{\mathbf{REG}}\\ \left(\%/\mathbf{day}\right)\end{array}$ |

1 | − | − | $0.833$ | $0.897$ | − | $0.922$ | − | $0.776$ |

2 | − | $3.615$ | − | $3.190$ | − | − | $0.345$ | $0.341$ |

3 | − | $4.686$ | $3.898$ | $3.229$ | − | $0.907$ | $2.226$ | $1.295$ |

**Table 4.**Average values ($\overline{pH}$, ${\overline{R}}_{acc}$, $\overline{\varphi}$, $\overline{T}$).

Plant | $\begin{array}{c}{\overline{\mathbf{pH}}}_{\mathbf{EP}}\end{array}$ | $\begin{array}{c}{\overline{\mathbf{pH}}}_{\mathbf{SP}}\end{array}$ | $\begin{array}{c}{\overline{\mathbf{pH}}}_{\mathbf{D}}\end{array}$ | $\begin{array}{c}{\overline{\mathbf{pH}}}_{\mathbf{G}}\end{array}$ | $\begin{array}{c}{\overline{\mathbf{R}}}_{\mathbf{acc}}\\ \left(\mathbf{L}/{\mathbf{m}}^{2}\right)\end{array}$ | $\begin{array}{c}{\overline{\mathbf{T}}}_{\mathbf{A}}\\ \left({}^{\circ}\mathit{C}\right)\end{array}$ | $\begin{array}{c}\overline{\mathsf{\varphi}}\\ (\%)\end{array}$ | $\begin{array}{c}{\overline{\mathbf{T}}}_{\mathbf{SP}}\\ \left({}^{\circ}\mathbf{C}\right)\end{array}$ | $\begin{array}{c}{\overline{\mathbf{T}}}_{\mathbf{D}}\\ \left({}^{\circ}\mathbf{C}\right)\end{array}$ |
---|---|---|---|---|---|---|---|---|---|

1 | $7.58$ | $7.55$ | − | $7.55$ | $68.11$ | $20.79$ | $77.56$ | $25.44$ | − |

2 | $6.07$ | − | $8.48$ | $7.44$ | $52.95$ | $19.80$ | $67.30$ | − | $26.86$ |

3 | $9.40$ | $7.95$ | $5.80$ | $7.95$ | $41.46$ | $22.60$ | $63.50$ | $21.74$ | $22.38$ |

Treatment | $\begin{array}{c}\mathbf{HRT}\\ \left(\mathbf{days}\right)\end{array}$ | $\begin{array}{c}\mathbf{Total}\phantom{\rule{4pt}{0ex}}\mathbf{Removed}\\ \left(\%\mathbf{COD}\right)\end{array}$ | $\begin{array}{c}\mathbf{Total}\phantom{\rule{4pt}{0ex}}\mathbf{Removed}\\ \left(\%\mathbf{COD}/\mathbf{HRT}\left(\mathbf{day}\right)\right)\end{array}$ | References |
---|---|---|---|---|

Anoxic-aerobic | 54 | $95.90$ | $1.78$ | [39] |

Anerobic-anoxic-aerobic | 48 | $95.00$ | $1.98$ | [39] |

Anaerobic | 14 | $94.00$ | $6.71$ | [40] |

Codigestion anaerobic | $15.5$ | $69.20$ | $4.46$ | [41] |

Anoxic-aerobic | 13 | $86.90$ | $6.68$ | [38] |

Anoxic-aerobic | 13 | $93.60$ | $7.20$ | [38] |

Activated Slugge | 10 | $95.00$ | $9.50$ | [38] |

NTSW Domestic | 20 | $96.00$ | $4.80$ | [6] |

NTSW Domestic | 28 | $90.00$ | $3.21$ | [4] |

NTSW Domestic | 30 | $90.00$ | $3.00$ | [7] |

NTSW Livestock | 25 | $65.00$ | $2.60$ | [37] |

SBR and MBR technology | $6.5$ | $96.00$ | $14.77$ | [47] |

Anaerobic-Biofilters | 6 | $98.00$ | $16.33$ | [45] |

Aerobic termofilic | 3 | $62.00$ | $20.67$ | [46] |

Anaerobic-SBR | $4.5$ | $96.70$ | $21.49$ | [42] |

MBR technology | 1 | $51.20$ | $51.20$ | [43] |

Aerobic termofilic | 3 | $60.00$ | $20.00$ | [44] |

NTSW Plant 1 | 81 | $72.64$ | $0.90$ | This work |

NTSW Plant 2 | 25 | $79.75$ | $3.19$ | This work |

NTSW Plant 3 | 28 | $91.70$ | $3.28$ | This work |

SBR | 6 | $70.40$ | $11.73$ | [39] |

SBR and MBR technology | 8 | $98.00$ | $12.25$ | [47] |

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## Share and Cite

**MDPI and ACS Style**

Mendieta-Pino, C.A.; Garcia-Ramirez, T.; Ramos-Martin, A.; Perez-Baez, S.O. Experience of Application of Natural Treatment Systems for Wastewater (NTSW) in Livestock Farms in Canary Islands. *Water* **2022**, *14*, 2279.
https://doi.org/10.3390/w14142279

**AMA Style**

Mendieta-Pino CA, Garcia-Ramirez T, Ramos-Martin A, Perez-Baez SO. Experience of Application of Natural Treatment Systems for Wastewater (NTSW) in Livestock Farms in Canary Islands. *Water*. 2022; 14(14):2279.
https://doi.org/10.3390/w14142279

**Chicago/Turabian Style**

Mendieta-Pino, Carlos A., Tania Garcia-Ramirez, Alejandro Ramos-Martin, and Sebastian O. Perez-Baez. 2022. "Experience of Application of Natural Treatment Systems for Wastewater (NTSW) in Livestock Farms in Canary Islands" *Water* 14, no. 14: 2279.
https://doi.org/10.3390/w14142279