Session 7 - Wastewater treatment

Preparation of activated carbon from agricultural bio-products is a promising way to produce useful adsorbents for Hg removal. In this study Aegina pistachio shells were used as raw materials and the activation was carried out by impregnation with ZnCl2 and heating at 750oC under N2 atmosphere. Three different levels of impregnation ratios (IR) were used for the chemical activation procedure, i.e. IR 1.0, 1.5 and 2.0 grams of ZnCl2 per gram of raw material. Further sulfurization treatment of the chemically activated carbons was also examined as a means to improve the adsorption capacity of activated carbons toward Hg. Overall six different types of activated carbons were produced and characterized regarding their physicochemical properties and their capacity to adsorb mercury. The specific surface area was determined by the BET method. The amount of acidic and basic function groups was determined with Boehm method and the surface chemical characteristics of activated carbons were investigated using the FT-IR spectroscopic method. Preliminary Hg adsorption experiments indicated that the sulfur modified carbons were much more efficient for the removal of Hg from aqueous streams compared to simple chemically activated carbons.

Session: 7, Room: A, at Thu, 09/05/2019 - 12:15 to 12:30
Oral presentation in Wastewater treatment

In this study, plastics industry wastewater (PIWW) characterized by high total and soluble chemical oxygen demand (tCOD and sCOD, up to ~2200 and ~1500 mg/L, respectively) and remarkable unbiodegradable soluble COD (usCOD, 508±224 mg/L, 31±14% of tCOD) concentrations was treated at laboratory scale using a hybrid moving bed biofilm reactor (MBBR). Interestingly, the MBBR showed average tCOD, sCOD and usCOD removal efficiencies of 26±6, 32±11 and 36±11%, respectively, which were comparable to those achieved by the coagulation/flocculation pre-treatment currently applied at full-scale. Such results encourage the application of MBBR as a cost-effective option for the removal of recalcitrant soluble organics from PIWW and other similar industrial wastewaters.

Session: 7, Room: A, at Thu, 09/05/2019 - 12:00 to 12:15
Oral presentation in Wastewater treatment

Aerobic degradation of effluents contains tetramethylammonium hydroxide molecules (TMAH), coming from an electronic industry, was studied at laboratory and pilot scale. At the first, the preliminary experiments were conducted using a lab scale reactor inoculated with activated sludge coming from urban wastewater treatment. Several batches have been performed on real effluent, in which TMAH concentration was about 1800 mg/L. The results showed that after acclimation, the microorganisms removed 99% of TMAH in seven days. Kinetic studies have provided the following kinetic parameters able to describe the trends of TMAH, ammonium ions and biomass concentration as a function of time in the reactor: KS = 0.8 g/L; µmax = 0.042 h-1. Then, in a second phase the experiments were conducted at pilot scale using a pilot plant realized within Life Bitmpas project (LIFE15 ENV/IT/000332). The plant has three biological reactors of 1 m3 and it is possible to feed up to 25 L/h of TMAH effluent. The experiments were conducted in a continuous mode and the results showed that in 8 days the total degradation of TMAH was 99%; moreover, from kinetic study have been determined the following kinetic parameters: Ks = 0. 83 g/L and µmax = 0.0074 h-1.

Session: 7, Room: A, at Thu, 09/05/2019 - 11:30 to 11:45
Oral presentation in Wastewater treatment

Tannery wastewater represent a hazard to the environment due to its high content of chromium. Conventional methods to purify this wastewater stream are available, but not capable to recover back chromium to the tannery process. Membranes appears to be a promising technology to achieve both targets of water purification and recycling of chromium.
The economic feasibility of the here proposed process relays on fouling minimization, in order to maximize the life of the employed membrane modules and as a consequence to keep the operational costs low. The use of an advanced control system capable to predict fouling incurrence and to adapt the operating conditions to sub-boundary ones appears to be the best strategy.
In this work, the proposed process, including the advanced control system, was simulated within HYSYS. By means of performed simulation runs, it was possible to avoid irreversible fouling operating conditions, still obtaining an adequate level of tannery wastewater treatment and relevant chromium recovery rates. Both the predictive and the adaptive part of the control system exhibits high reliability. The developed strategy appears therefore promising to encourage the use of membrane technologies for this application with feasibility from a technical and economic point of view.

Session: 7, Room: A, at Thu, 09/05/2019 - 11:45 to 12:00
Oral presentation in Wastewater treatment

Cyprus is experiencing severe water supply deficiency. Particularly in summer months the situation is aggravated mainly due to low precipitation, high evaporation and increased demands for irrigation and tourisms. The use of treated wastewaters for environmental purposes such as recharging aquifers, agricultural irrigation and municipal landscape is highly contributing in the scarcity problem. In Cyprus there are 8 large urban plants and 25 small community plants for domestic waste treatment. Various chemical analysis including Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), suspended solids, anions, total phosphorus, total nitrogen, toxic metals, pesticides and polycyclic aromatic hydrocarbons (PAHs) are contacted to ensure the quality of the treated wastewater. Instrumental techniques like ion chromatography, ICP, GC-MS and HPLC-fluorescence are used to determine ions, metals, pesticides and PAH,'s. In this study, the results of these analyses are presented for treated urban wastes. Heavy metals, boron, pesticides and PAHs are found in low concentrations ranging from low micrograms to milligrams per liter.

Session: 7, Room: A, at Thu, 09/05/2019 - 12:30 to 12:33
Flash presentation in Wastewater treatment

In this study the performance of impregnated resin was evaluated as the sorbent for the removal of lead ions from aqueous solutions. It was observed that the lead removal efficiency depends on the sorbent dose, initial concentration of metal ions, pH of water and the contact time. The results of batch experiments showed the highest removal efficiency of Pb(II) ions from water (>99%) at L:S = 100:1 for the following conditions: initial concentration of metal ions of 10 mg/dm3, pH = 6, and contact time of 60 min. The experimental equilibrium data were also described by sorption isotherms. Impregnated resin as novel sorbent has been found efficient and easily regenerable and can be used several times.

Session: 7, Room: A, at Thu, 09/05/2019 - 12:33 to 12:36
Flash presentation in Wastewater treatment

More strict environmental regulations on the discharge of toxic metals require developing various technologies for their removal from polluted streams. The separation of toxic metal ions using immobilized membranes with doped ligands, due to their high selectivity and removal efficiency, increased stability, and low energy requirements, is promising for improving the environmental quality. Cellulose triacetate-based polymer inclusion membranes (PIMs), with macrocyclic ligands as ion carriers, were studied for their ability to transport of toxic metal ions from aqueous solutions. The effect of concentration of ion carrier, pH of source aqueous phase, stripping agents on the effective transport of toxic metal ions have been assessed. All studied parameters were found to be important factors for the transport of toxic metal ions. The initial flux was determined for different conditions of transport through polymer inclusion membranes. The newly developed PIM containing macrocyclic ligands were found to be stable and highly permeable. Moreover, the prepared membranes could be potentially suitable for multiple use process for efficient removal of toxic metal ions from aqueous solutions.

Session: 7, Room: A, at Thu, 09/05/2019 - 12:36 to 12:39
Flash presentation in Wastewater treatment