Global NEST Journal

ISSN:

Print ISSN: 1790-7632

Electronic ISSN: 2241-777X

Issue 3

Volume number:

11

Publication year:

2009

Publication month:

November

Papers presented at 9th International Conference on Protection and Restoration of the Environment - PRE9, June 30 - July 3, 2008, Kefalonia, Greece

Articles

Lead exposure through Drinking Water: Lessons to be learned from recent U.S. experience

Triantafyllidou S., Lambrinidou Y. and Edwards M., Pages:341-348

DOI:

https://doi.org/10.30955/gnj.000607

Paper Topic:

General

Issue:

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Abstract

Lead (Pb) particles that detach from the plumbing and contaminate drinking water can pose a
significant health threat, which is often underestimated. Laboratory simulation of this problem
revealed that standard quantification protocols in the US may miss 80% of the lead present in
the water. At the same time, a significant fraction of this undetected particulate lead may be
bioavailable when ingested. A critical review of the Washington DC lead-in-water crisis
suggested that lead in water might constitute a greater public health risk than generally
acknowledged, in at least some circumstances. It also revealed deficiencies in the public
health response as well as in alerting the public to elevated levels of lead, and the subject
continues to be mired in controversy. Our independent testing at six Washington DC public
schools in 2008 showed that problems with elevated lead still persist at 2-41% of taps
sampled at each school, even after remedial measures were implemented.

Removal of Specific DBP by GAC in Galatsi (Athens) WTP

Lekkas T.D., Babi K., Koumenides K., Makri C.A., Lekkas D.F. and Nikolaou A.D., Pages:349-356

DOI:

https://doi.org/10.30955/gnj.000610

Paper Topic:

General

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Abstract

The objective of this pilot-study is to evaluate the Granular Activated Carbon (GAC)
performance for the removal of specific disinfection by-products (DBPs), trihalomethanes
(THMs) and haloacetic acids (HAAs), from Athens drinking water. For this purpose, a GAC
pilot filter-adsorber was operated in Galatsi WTP, Athens, for 235 days, until the GAC
removal efficiency for individual THMs, HAAs and DOC was almost eliminated
(breakthrough). From the experimental results, GAC bed life, GAC loading, carbon usage
rate, and operation time to breakthrough for most THMs and HAAs were calculated.
The average influent concentrations of the more chlorinated THMs and HAAs were higher
than those of less chlorinated and more brominated species and their mass adsorbed on the
GAC column was also higher, as expected according to Freundlich isotherm. TCA, TCM and
DCA had the highest influent concentrations and they seemed to be better adsorbed than the
rest. TBM, TBA and DBCA were almost not detected in feed water.
Comparison of the GAC loading at breakthough for pairs of compounds with similar average
influent concentration showed that TCA is better adsorbed than TCM and that BDCA is better
adsorbed than MCA, BDCM and DBCM.
Desorption phenomena of some THMs and HAAs, probably caused by a sudden drop in
influent concentration, were also noticed.
The above findings represent real operation conditions for Athens drinking water.
Further research is recommended on methods to reduce desorption from carbon beds.

Disinfection of municipal wastewater by TiO2 photocatalysis with UV-A, visible and solar irradiation and BDD electrolysis

Melemeni M., Stamatakis D., Xekoukoulotakis N.P., Mantzavinos D. and Kalogerakis N., Pages:357-363

DOI:

https://doi.org/10.30955/gnj.000604

Paper Topic:

General

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Abstract

The efficiency of TiO2 photocatalysis induced by ultraviolet and visible irradiation and salt-free
electrolysis over boron-doped diamond electrodes to inactivate total (TC) and fecal (FC)
coliforms in secondary treated municipal wastewater was evaluated. Photocatalytic
experiments were conducted with two types of titania (Degussa P25 and sulfur-doped
catalyst) at loadings in the range 0.1-0.5 g l-1 and three types of irradiation, i.e. artificial UV-A,
artificial visible and solar. Electrolysis was conducted in a flow-through cell at anodic current
densities of 14.3 and 28.6 mA cm-2 without the addition of auxiliary chemicals. Inactivation
followed a first-order kinetic expression with regard to bacteria population and the rate was
dependent of the experimental conditions in question. In general, electrochemical disinfection
was up to about two orders of magnitude faster than photocatalysis; for instance, TC
population decreased to less than 5% of the initial population after 9 and 4 min at 14.3 mA
cm-2 and 28.6 mA cm-2 respectively. Similar efficiencies with TiO2 photocatalysis would
require at least 30 min of contact time. Interestingly, energy consumption for the
electrochemical process was computed to about 0.5 kWh per m3 of treated effluent, well
below the respective value for photocatalysis.

Anaerobic digestion of olive mill wastewater

Blika P.S., Stamatelatou K., Kornaros M. and Lyberatos G., Pages:364-372

DOI:

https://doi.org/10.30955/gnj.000605

Paper Topic:

General

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Abstract

Anaerobic digestion of olive-mill wastewater (OMW) was carried out in a continuously fed
mode bioreactor. The bioreactor was operated at different hydraulic retention times (HRTs),
using OMW, either raw or pre-treated with white-rot fungi. Two different kinds of feed were
tested in this process, one which was thermally treated and subjected to sedimentation, in
order to remove the solids contained and the other without any physicochemical treatment
(raw OMW). Thermally pretreated OMW did not allow a stable operation even at an HRT of
30d. Further pretreatment of the OMW with a white-rot fungus for removal of the contained
phenolics, allowed a stable operation at an HRT of 30 d. On the other hand, simple dilution of
the raw wastewater, without any solids removal, lead to a stable operation at an HRT of 30d
and was accompanied by higher production of biogas. The presence of the solids in the OMW
proved to be a determining factor for the stability of the process and could be attributed to a
possible adsorption on the solids of hydrophobic compounds, such as long-chain fatty acids
that are toxic to methanogens.

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Global NEST Journal

Issue 3

Articles

Lead exposure through Drinking Water: Lessons to be learned from recent U.S. experience

Removal of Specific DBP by GAC in Galatsi (Athens) WTP

Disinfection of municipal wastewater by TiO2 photocatalysis with UV-A, visible and solar irradiation and BDD electrolysis

Anaerobic digestion of olive mill wastewater

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