Removal and Reuse of Collagen, Gelatine and Total Chromium from a Raw Leather Industry Wastewater using a Sequential Up flow Anaerobic Sludge Blanket Digestion (UASB) / Aerobic Forward Osmosis (FO) Reactor Configuration

Abstract

Collagen, gelatine and total chromium recovery was achieved from the sequential upflow anaerobic sludge blanket digestion (UASB) reactor sludge and concentrate of forward osmosis (FO) treating raw leather industry wastewater. It is aimed to reduce the cost of raw materials in leather industry process by reusing the collagen, gelatine and total chromium from the leather industry process during tanning. The recoveries of collagen and gelatine, total chromium was 78%, 80% and 27% respectively from the waste sludge in UASB process while the recoveries of these chemicals were 95%, 96% and 99% in the concentrate of FO. The maximum 85% CODtotal, 94% CODdissolved, 89% total-N, 88% total-P, 87% color, 87% total chrome (Cr+3 + Cr+6), 86% TOC, 87% SO3-2, 90% percentage of exchangeable sodium, 87% sodium adsorption rate (SAR), 84% sodium carbonate residue (RSC), 92% Cl-1, 92% SO4-2, 93% total salt, 88% B+3, 94% NO3-, 94% NH4+, 99% fecal coliform, 94% TSS, 93% EC25x106 removal efficiencies were measured to output anaerobic UABS reactor in leather industry wastewater. The maximum 99% CODtotal, 99% CODdissolved, 99% total-N, 99% total-P, 99% color, 99% total chrome (Cr+3 + Cr+6), 99% TOC, 99% SO3-2, 99% percentage of exchangeable sodium, 99% sodium adsorption rate (SAR), 99% sodium carbonate residue (RSC), 99% Cl-1, 99% SO4-2, 99% total salt, 99% B+3, 99% NO3-, 99% NH4+, 99% fecal coliform, 99% TSS, 99% EC25x106 removal efficiencies were observed to output aerobic FO reactor in leather industry wastewater. The costs of anaerobic UASB and aerobic FO processes are 0.57 euro and 0.145 euro, respectively, to treat 1 m3 leather industry wastewater. The cost of the consecutive total system is 0.715 euro for the treatment of 1m3 leather industry wastewater. The methane gas obtained in the UABS reactor is electrical energy and the electrical energy income was calculated as 1.9 euro from 1 m3 anaerobic waste sludge. The income to be obtained from the recovery of total chromium, collagen and gelatine from UABS and FO process is 2.75 Euro/l. As a result, the total cost decreases from 1.55 Euro/l to 0.715 Euro/l after aerobic FO process. The cost of these consecutive treatment processes is reduced by the production of methane gas and is increased the recovery of economic chemicals.