2020 journal article
Evaluation of chemical polymers as coagulation aids to remove suspended solids from marine finfish recirculating aquaculture system discharge using a geotextile bag
AQUACULTURAL ENGINEERING, 90.
author keywords: Recirculating aquaculture systems; Effluent management; Solid waste capture; Flocculant aid; Polyacrylamide (PAM) polymers; Geotextile bag; Geotube
UN Sustainable Development Goal Categories
14. Life Below Water
(Web of Science; OpenAlex)
Source: Web Of Science
Added: August 10, 2020
Traditionally used in the construction and excavation industries to remove solids from runoff, geotextile fabric tube (Geotube) technology has been adopted by freshwater aquaculture facilities as a method of effluent management. The effectiveness of a Geotube is improved by using chemical polymers to bind suspended solids in the effluent for greater retention; however, polymers used in freshwater systems may not be effective in marine systems. Using laboratory jar tests, seven organic polymers of different molecular weights and ionic charges were evaluated at doses ranging from 0 to 50 ppm for solids removal efficiency (SRE) from effluent from a marine (33 ppt) finfish RAS growing black sea bass. Of the seven polymers screened, two cationic high molecular weight polyacrylamide polymers Drewfloc (DF) 2449 and DF 2468 had high SRE of total suspended solids (TSS) (36.1–84.4 %). Further tests using miniature geotextile bags confirmed that DF 2449 at 10 ppm and DF 2468 at 5 ppm had high SRE (73.3–75.9%) compared to the untreated control (43.4 %). When applied to a commercial-scale Geotube, DF 2449 at 10 ppm removed 92.1 % of the TSS in the effluent of the marine finfish RAS growing black sea bass. Rinsing the saline biosolids with freshwater at a rate of 1.63 L per 100 g dry solids reduced the salinity to < 1 ppt, a level safe for land application, while 4.43 L per 100 g dry solids were needed to reduce the salinity to 0.16 ppt. Geotube systems are effective at removing TSS from intensive, marine RAS discharge as well as meeting NPDES discharge compliance and reducing the impact of aquaculture on local waters.