Abstract
Abstract The use of a crop to remove nutrients from brewery effluent and the influence of pH on these removal rates was evaluated. Cabbage (Brassica oleracea) was grown in recirculating hydroponic systems fed with post-anaerobically digested brewery effluent (BE) either subject to pH adjustment (6.5–7.0) or unaltered pH (8.0–8.5). These were compared with cabbages grown in water only and in a inorganic fertiliser nutrient solution (NS). Hydroponic systems fed with pH adjusted BE removed significantly more nitrogen and phosphorus than systems fed with pH unadjusted BE (p < 0.05). The final weight of cabbages from the pH adjusted BE systems were 6.7 times greater than cabbages from the pH unadjusted BE systems, whereas pH adjustment had no influence on cabbage weight in the water-only and NS treatments. Anaerobically digested BE that is not pH adjusted is not a suitable water and nutrient source for the hydroponic production of cabbages. However, pH adjustment of BE renders it more suitable for hydroponic crop production with hydroponic systems decreasing dissolved inorganic nitrogen, ammonium, phosphate and chemical oxygen demand concentrations by 72.8, 31.8, 98.5 and 51.0%, respectively. Hydroponic systems can be used to treat post-anaerobically digested BE to a similar standard obtained by conventional activated sludge treatment system.
Highlights
Effluent, from the beer making process, at Ibhayi brewery in Port Elizabeth is treated onsite for reuse in non-production activities or discharge to the municipal sewer
The conductivity of brewery effluent (BE) and water-only treatments did not change while the conductivity of nutrient solution (NS) treatments p-value pH Conductivity dissolved oxygen (DO) chemical oxygen demand (COD) Total inorganic nitrogen (TIN) NH4-N NO2-N NO3-N PO4-P Cl Na
The pH adjustment of post-Primary facultative pond (PFP) BE had a major influence on the growth, health and chemical composition of cabbage plants grown in hydroponic systems
Summary
From the beer making process, at Ibhayi brewery in Port Elizabeth is treated onsite for reuse in non-production activities or discharge to the municipal sewer. Effluent is treated via anaerobic digestion (AD), activated sludge (AS) micro- and ultra-filtration. The AS treatment process removes nitrogen and decreases the chemical oxygen. Activated sludge is an energy intensive treatment process, as agitators are required to provide oxygen to the aerobic micro-organisms responsible for effluent treatment (Simate et al ). There is a need to identify alternative energy efficient, low waste production systems for effluent treatment that can be used to replace AS
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