Reusing industrial by-products to enhance phosphorus removal in waste stabilization ponds: laboratory approach

Abstract

21Waste stabilization ponds (WSP), in spite of being a suitable technology for wastewater 22 treatment, present low phosphorus removal. This study aimed at evaluating the net 23 increase on phosphorus removal efficiency in microcosm WSP in which sludge was 24 conditioned with an adsorbent (industrial by-product) having a high phosphorus 25 retention capacity. In order to determine the best candidate to condition the sludge, four 26 different industrial by-products (granular bentonite; fly ashes from a municipal solid 27 waste incineration plant and two types of fly ashes from power plants) were tested for 28 their phosphorus adsorption capacity. Experimental results were fitted to Langmuir and 29Freundlich models. All adsorbents showed a high phosphorus adsorption capacity. 30Maximum phosphorous adsorption capacity estimated from Langmuir equations ranged 31 between 34.7 and 74.0 mg P/g adsorbent, being fly ashes from a power plant and 32 granular bentonite the adsorbents with the highest and lowest adsorption capacity, 33 respectively. Microcosms WSP were set up and the sludge conditioned with fly ashes 34 from a municipal solid waste incineration plant. Results showed that phosphorus 35 removal efficiency increased up to 90% by adding 5% of adsorbent (in terms of weight 36 of adsorbent to weight of sludge). Main conclusion is that of industrial by-products may 37 be a low cost solution for enhancing phosphorus removal in WSP. 38 39