Using Salt Marsh Plants in Phytoremediation of Liquid Effluent in ...

Using Salt Marsh Plants in Phytoremediation of Liquid Effluent in Enhanced Marine Recirculating Aquaculture Systems
 1Gulf

Joesting1*,

Biber1,




Heather Patrick Reginald Blaylock1, and Douglas Drennan2
 Coast Research Laboratory, University of Southern Mississippi, Ocean Springs, MS
 2Aquaculture Systems Technology LLC, New Orleans, LA

System Description

Introduction Enhanced Recirculating Marine Aquaculture (ERMA) systems alleviate many of the perceived risks associated with traditional aquaculture. However, the high stocking densities required to make ERMA competitive present additional challenges, especially with regard to effluent management. An effluent treatment system combining geotextile bags and an engineered approach to bioclarification, disinfection/ sterilization, and dentirification has been shown to significantly reduce nutrient levels of effluent, but nutrient concentrations often remain above levels required to sustain fish production. Plants have been used successfully in freshwater aquaculture systems to reduce nutrient concentrations to levels required for fish production, allowing treated effluent to be recycled through the system and reducing environmental and economical costs.

Closed Loop ERMA Schematic RAS facility

Sludge sump

Geotextile bags (primary treatment) N ~ 59% P ~ 10%

Spotted Seatrout

Sludge sump and geotextile bags

Salt marsh species:

Greenhouse

1. Distichlis spicata

Goal: N ~ 82% P ~ 83%

2. Juncus roemerianus

Supernatant tank

3. Panicum amarum

N ~ 63% P ~ 66%

4. Schoenoplectus americanus Plant raft systems

5. Spartina alterniflora

Secondary treatment

6. Spartina patens

Supernatant tank

Objective

Components of Secondary Treatment: !   Propeller Washed Bead Filter for bioclarification

The objective of this study is to investigate the use of salt marsh plants to reduce nitrate and phosphate levels by additional 50% in treated effluent from a spotted seatrout (Cynoscion nebulosus) hatchery while maintaining the salinity of the liquid effluent.

Methods Monocultures of six salt marsh species will be randomly placed in two cells each and measured for: !   Survival / mortality

!   UV Sterilizer for disinfection/ sterilization !   Foam fractionator with ozone for breaking down refractory organics

Multi-trophic greenhouse with plant raft systems

Water from each raft system and a collection sump will be sampled weekly for nutrient analyses (nitrogen and phosphate) and compared to water quality requirements for spotted seatrout production.

!

Dentrifrication reactor

Table 1: Salinity, pH, total ammonium nitrogen (TAN), nitrite (NO2-N), nitrate (NO3-N), and dissolved reactive phosphate (DR-PO4) from three portions of the primary treatment (sludge sump tank, geotextile bag, supernatant tank), the secondary treatment, and anticipated plant raft system reduction. Salinity (ppt)

pH

TAN (mg/L)

NO2-N (mg/L)

Sludge Tank

26.0

8.37

14.81

Geobag

14.0

8.29

5.05

Supernatant Tank

14.0

9.21

Secondary Treatment

29.0

8.20

Plant Raft System

14.0

9.21

!   Plant size !   Tissue nutrient content

Engineered secondary effluent treatment system

NO3-N (mg/L)

DR-PO4(mg/L)

0.505

177

32.4

0.430

73.2

29.1

0.59

0.018

65.2

11.0

0.48

0.082

12.4

3.8

--

0.081

31.9

5.5

Funding Source: Mississippi-Alabama SeaGrant Consortium, Aquaculture Research NSI 2010