Settling/Sedimentation Followed by Sorption with <i>Pinus sylvestris</i> Sawdust as “Green” Sorbent: On-Site Treatment of a Real Industrial Wastewater

Abstract

Whereas the pulp and paper industrial sector-considered the second highest consumer of freshwater in Europe-has already been provided with sufficient wastewater characterization and treatment technologies, other wood-based industries (e.g. furniture, floor production), which do not use water for manufacturing processes, generate different wastewater streams after: 1) cleaning/washing of machinery that applies adhesives and coatings onto wood surfaces; 2) cleaning/washing of machinery that applies specific products for the curing phase of adhesives; 3) cleaning/washing of sharp planar blades used for the sawn process and to prepare wood surfaces for the adhesive application; 4) cleaning/washing of the floor; 5) cleaning/washing of trucks and vehicles. The dilution of low-volumes of highly polluted wastewater is not acceptable any longer since conventional treatment plants are not designed for these types of industrial wastewater. There is a need for proper characterization, treatability studies, designing and testing alternative small size and cost-effective treatment systems for on-site implementation. Treatment systems based on sorption mechanisms are flexible, easy to operate and generate less sludge and several low-cost sorbents generated by forestry activities have advantageous physico-chemical characteristics. The current paper presents the preliminary results from a pilot treatment system consisting of an equalization tank, settling/sedimentation and two sorption reactors in parallel using Pinus sylvestris sawdust as sorbent implemented as part of an integrated water management plan in a wood-floor industry. The simple to operate and cost-effective pilot treatment system performs satisfactorily during an initial period of operation. The study shows an average 39% -54% reduction of TPH; 17% -38% reduction of oil; 2% -15% of reduction of COD and; 11% -74% reduction of most toxic metals but for Co, Ni and Zn in the system B. Based on these results, Pinus sylvestris sawdust is a potential low-cost and abundant material to be considered for industrial wastewater treatment plants. F. Kaczala et al. 369