INVESTIGATION INTO THE SUITABILITY OF SAWDUST WASTE AS A MEDIUM FOR AQUACULTURE EFFLUENT TREATMENT
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Date
2021-03
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UNIVERSITY OF ILORIN
Abstract
Water is a renewable resource which should be preserved and protected. Untreated wastewater from aquaculture such as catfish farming most times end up in water bodies which could be sources of water supply downstream. Such water, if untreated before use or discharge into water bodies could result in eutrophication and human diseases. Untreated effluent from catfish farming can thus have these consequences. Therefore, there is a need to examine how the effluent from aquaculture can be treated before discharge. The aim of this study was to investigate the suitability of sawdust waste as a medium for aquaculture effluent treatment. The objectives of the study were to: (i). investigate current practice of Catfish Farming Effluent CFE disposal; (ii). assess quality of CFE; (iii). examine the adsorption abilities of sawdust, Activated Sawdust (AS), and Commercial Activated Carbon (CAC); and (iv). investigate the efficiency of AS in the treatment of CFE.
The methodology employed involved treatment of CFE using adsorption via a batch process in the laboratory and conversion of two different types of sawdust: homogenous (Isoberlina doka wood specie) and heterogeneous mix (Daniella ogea, Anogesus olivera, Isoberlina doka, Afzelia bipinensis and Gmelina arborea). Wastewater was collected from different catfish farms within Ilorin, the study area. Sawdust was converted into AS using orthophosphoric acid as the activating agent based on a 3-factorial design. The factors considered were molarity of acid, temperature and activation period. Treatment of CFE was investigated using the following physicochemical parameters: Total Dissolved Solids (TDS), Biochemical Oxygen Demand (BOD), nitrite, nitrate and phosphorus. The CFE was also treated with CAC. The laboratory analysis was conducted using Standard Methods.
The findings of the study were that:
(i). CFE is currently discharged untreated through pipes from ponds into open drains;
(ii). untreated effluent has TDS, BOD, nitrite, nitrate and phosphorus values of 520 mg/l, 17.4 mg/l, 0.42 mg/l, 150.45 mg/l and 2.48 mg/l, respectively while the discharge limits are 2000 mg/l; 6.0 mg/l; 0.08 mg/l; 40 mg/l; and 3.5 mg/l, respectively;
(iii). after treatment with sawdust, AS and CAC, TDS reduced from 520 mg/l to 150 mg/l, 210 mg/l and 260 mg/l; BOD from 17.4 mg/l with no change with sawdust, 9.8 mg/l and 9.9 mg/l; nitrite from 0.42 mg/l to 0.32 mg/l, 0.07 mg/l and 0.31 mg/l; phosphorus from 2.48 mg/l to 2.2 mg/l, 2.12 mg/l and 2.19 mg/l. However, nitrate increased in value from 150.45 mg/l to 175.8 mg/l, 156.1 mg/l and 200 mg/l; and
(iv). the efficiency of AS treatment for phosphorus, BOD, TDS and nitrite were 12 %, 44 %, 60 %, and 83 %, respectively.
The study concluded that activated sawdust has the potential as an adsorbent for treatment of aquaculture wastewater which simultaneously solves the problem of indiscriminate sawdust disposal. The study recommended that AS should be adopted for the treatment of CFE prior to discharge into water bodies.
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Keywords
SUITABILITY, SAWDUST WASTE, AQUACULTURE EFFLUENT TREATMENT