Simultaneous Treatment of Agro-Industrial and Industrial Wastewaters: Case Studies of Cr(VI)/Second Cheese Whey and Cr(VI)/Winery Effluents

Abstract

Hexavalent chromium (Cr(VI)) was co-treated either with second cheese whey (SCW) or winery effluents (WE) using pilot-scale biological trickling filters in series under different operating conditions. Two pilot-scale filters in series using plastic support media were used in each case. The first filter (i.e., Cr-SCW-filter or Cr-WE-filter) aimed at Cr(VI) reduction and the partial removal of dissolved chemical oxygen demand (d-COD) from SCW or WE and was inoculated with indigenous microorganisms originating from industrial sludge. The second filter in series (i.e., SCW-filter or WE-filter) aimed at further d-COD removal and was inoculated with indigenous microorganisms that were isolated from SCW or WE. Various Cr(VI) (5-100 mg L −1) and SCW or WE (d-COD, 1000-25,000 mg L −1) feed concentrations were tested. Based on the experimental results, the sequencing batch reactor operating mode with recirculation of 0.5 L min −1 proved very efficient since it led to complete Cr(VI) reduction in the first filter in series and achieved high Cr(VI) reduction rates (up to 36 and 43 mg L −1 d −1 , for SCW and WW, respectively). Percentage d-COD removal for SCW and WE in the first filter was rather low, ranging from 14 to 42.5% and from 4 to 29% in the Cr-SCW-filter and Cr-WE-filter, respectively. However, the addition of the second filter in series enhanced total d-COD removal to above 97% and 90.5% for SCW and WE, respectively. The above results indicate that agro-industrial wastewater could be used as a carbon source for Cr(VI) reduction, while the use of two trickling filters in series could effectively treat both industrial and agro-industrial wastewaters with very low installation and operational costs.

Dairy By-Products: A Review on the Valorization of Whey and Second Cheese Whey

“…The crystal’s dimensions, the concentration factor and the qualitative properties corresponded to data provided in literature for lactose obtained from conventional cheese whey. The authors concluded that the results can be used to implement the crystallization process for manufacture of lactose from SCW [ 98 ].…”

“…Zeolite nitrogen from SCW can be a fertilizing agent [21] Results indicate that the agro-industrial wastewater could be used as a carbon source for Cr (VI) reduction [98] Production of a ready to drink beverage produced from SCW with fruit puree…”

Optimization of the Forward Osmosis Process Using Aquaporin Membranes in Chromium Removal

“…There are a number of conventional techniques for Cr(VI) removal from industrial wastewaters and aqueous solutions, such as chemical precipitation, absorption, biosorption, ionexchange, electrochemical method etc. However, these methods have major drawbacks such as low affordability, difficult application, and not being environmentally friendly [11,12]. Membrane-based filtration technologies like reverse osmosis (RO) and nanofiltration (NF) have some advantages like high efficiency and ease of use [13], and have been extensively applied for the removal of heavy metals.…”

Dairy By-Products: A Review on the Valorization of Whey and Second Cheese Whey

“…Using a pilot-scale biological trickling filters in series with different operating conditions, Tatoulis et al co-treat hexavalent chromium (Cr(VI)) with second SCW or winery effluents. The authors concluded that the agro-industrial wastewater could be used as a carbon source for Cr(VI) reduction, while the use of two trickling filters in series could effectively treat both industrial and agro-industrial wastewaters with very low installation and operational costs[90].Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 20 April 2021 doi:10.20944/preprints202104.0545.v1…”