Fabio Masi

Treatment of segregated black/grey domestic wastewater using constructed wetlands in the Mediterranean basin: the zer0-m experience

Concerns about water shortage and pollution have received increased attention over the past few years, especially in developing countries with warm climate. In order to help local water management in these countries, the Euro-Mediterranean Regional Programme (MEDA) has financed the Zer0-m project (E-mail: www.zer0-m.org). As a part of this project, several constructed wetland (CW) pilot systems with different pre-treatments have been implemented in four Technological Demonstration Centres in Egypt, Morocco, Tunisia and Turkey. The aim of this research was to establish appropriate designs for treatment of segregated domestic black (BW) and grey water (GW). We tested several different multistage CW configurations, consisting of horizontal and vertical subsurface flow CW for secondary treatment and free water systems as tertiary stage. CW removal efficiencies of TSS, COD, BOD(5), N-NH(4)(+), N-NO(3)(-), N(tot), total coliforms (TC) were evaluated for each of the implemented systems. The results from this study demonstrate the potential of CWs as a suitable technology for treating segregated domestic wastewater. A very efficient COD reduction (up to 98%) and nitrification (92-99%) was achieved for BW and GW in all systems. CW effluent concentrations were below 15 mg/L for BOD(5), 1 mg/L for N-NO(3)(-) and 0.5 mg/L for N-NH(4)(+) together with acceptable TC counts. Based on these results, we suggest adopting the design parameters used in this study for the treatment of segregated wastewater in the Mediterranean area.

Impact of influent wastewater quality on nitrogen removal rates in multistage treatment wetlands.

Nitrogen removal in treatment wetlands is influenced by many factors, and the presence of electron donors (biodegradable organic matter) and electron acceptors (nitrate ions) is the main limiting one; for obtaining these conditions, multistage treatment wetlands (MTWs) are required, where an extensive nitrification can be obtained in the first stages under aerobic conditions leaving then to the following anoxic/anaerobic stages the duty of the denitrification. Most of the biodegradable organic matter is however oxidised in the first stages, and therefore, the inlet to the denitrification beds is usually poor of easily degradable carbon sources. This study is comparing the long-term performances obtained at several MTWs operating in Europe (North and South) and North Africa in order to understand if there is a significant avail in making use of the influent chemical oxygen demand (COD)/N ratio during the design phase for ensuring proper performances in terms of N overall removal. The statistic analysis performed in this study have shown that MTWs are capable to ensure sufficient removal of both organic and nutrients even in unfavourable proportions of macronutrients (C and N). The usual assumptions for conventional biological treatment systems concerning adequate C/N ratios seem to be dubious in case of wastewater treatment in MTWs.

Multi-stage constructed wetland systems for municipal wastewater treatment

In the present paper the detailed design and performances of two municipal wastewater treatment plants, a four-stage constructed wetlands (CW) system located in the city of Dicomano (about 3,500 inhabitants) in Italy, and a three-stage CW system for the village of Chorfech (about 500 inhabitants) in Tunisia, are presented. The obtained results demonstrate that multi-stage CWs provide an excellent secondary treatment for wastewaters with variable operative conditions, reaching also an appropriate effluent quality for reuse. Dicomano CWs have shown good performances, on average 86% of removal for the Organic Load, 60% for Total Nitrogen (TN), 43% for Total Phosphorus (TP), 89% for Total Suspended Solids (TSS) and 76% for Ammonium (NH4(+)). Even the disinfection process has performed in a very satisfactory way, reaching up to 4-5 logs of reduction of the inlet pathogens concentration, with an Escherichia coli average concentration in the outlet often below 200 UFC/100 mL. The mean overall removal rates of the Chorfech CWs during the monitored period have been, respectively, equal to 97% for TSS and Biochemical Oxygen Demand (BOD5), 95% for Chemical Oxygen Demand (COD), 71% for TN and 82% for TP. The observed removal of E. coli by the CW system was in this case 2.5 log units.

Particle Size Distribution of Organic Compounds in Aqueous Aerosols Collected from Above Sewage Aeration Tanks

Several classes of organic compounds were analyzed in aqueous aerosols collected in June, November, and December 1996 from above the sewage aeration tanks of a treatment plant (Prato, Italy). Particle size distribution of organic compounds and their enrichment ratio (Er) with respect to the magnesium ion were determined to infer the extent to which various species were aerosolized. Organic components were found to be predominantly enriched in fine and large particles of the aerosol and their transfer may be attributed to the 1) adsorption of surfactant organic matter at the air/water interface (such phenomenon is particularly evident for the fine and ultra-fine fractions) and 2) flotation of colloidal matter from wastewater to the largest particles with consequent transport of the adsorbed organic compounds. In addition, the interaction of surfactants with hydrophobic compounds explained the enrichment of the latter in the finest fractions.

Transport of organochlorine pesticides across the air/sea interface during the aerosol process

Abstract A modified Gershey apparatus was used to study the transfer to the atmosphere of selected organochlorine; pesticides from salt solutions with and without the addition of ionic and non-ionic surfactants at different concentrations and from untreated and filtered Tyrrhenian sea water. Pesticides were transported into the atmosphere both in the gas phase land in the liquid aerosol depending on their chemical structure and their physical characteristics (surface properties, volatility, water solubility, hydrophobicity). The results obtained gave useful information about the behaviour of the tested organocthlorinated compounds in long-range transport from temperate environments to frigid polar regions.

Organic Compounds in Antarctic Sea-Water and Pack-Ice

Abstract Pack-ice and sea-water samples collected at different depths from Terra Nova Bay and Ross Sea, during 1990/1991 Italian Antarctic Expedition, were analyzed using HRGC and GC-MS. Several classes of biogenic and anthropogenic organic compounds were identified and measured in both matrices. The results showed the changes in the organic composition at varying depths of pack-ice and sea-water and the enrichment of organic compounds in the pack.

Wineries wastewater treatment by constructed wetlands: a review

The application of wetland systems for the treatment of wineries wastewater started in the early 1990s in the USA followed a few years later by France, Italy, Germany and Spain. Various studies demonstrated the efficiency of constructed wetlands (CWs) as a low cost, low maintenance and energy-saving technology for the treatment of wineries wastewater. Several of these experiences have also shown lessons to be learnt, such as some limits in the tolerance of the horizontal subsurface flow and vertical subsurface flow classic CWs to the strength of the wineries wastewater, especially in the first stage for the multistage systems. This paper is presenting an overview of all the reported experiences at worldwide level during the last 15 years, giving particular attention and provision of details to those systems that have proven to get reliable and constant performances in the long-term period and that have been designed and realized as optimized solutions for the application of CW technology to this particular kind of wastewater. The organic loading rates (OLRs) applied to the examined 13 CW systems ranged from about 30 up to about 5,000 gCOD/m² d (COD: chemical oxygen demand), with the 80th percentile of the reported values being below 297 gCOD/m² d and the median at 164 gCOD/m² d; the highest OLR values have in all cases been measured during the peak season (vintage) and often have been linked to lower surface removal rates (SRRs) in comparison to the other periods of the year. With such OLRs the SRRs have ranged from a minimum of 15 up to 4,700 gCOD/m² d, with the 80th percentile of the reported values being below 308 gCOD/m² d and the median at 112 gCOD/m² d.

The Tertiary Treatment Pilot Plant of Publiser SPA (Florence, Tuscany): A Multistage Experience

The multiservice company PubliSer SpA has constructed and monitored the operation of a multistage tertiary constructed wetlands wastewater treatment pilot plant for experimental and demonstration purposes. The facility was designed by and is partially monitored by the environmental engineering company IRIS SaS in Cerbaia, Florence, Italy. The experimentation with natural wastewater tertiary treatments is particularly important within central Italy as there are recurring environmental problems related to the poor functioning of small wastewater treatment systems. The present study is designed to compare the utility and efficiency of different multistage configurations following an active sludge process through an intensive monitoring programme that was initiated in November 1997. In this paper, we report the principal design specifications, a detailed description of the pilot plant, the dimensioning criteria and an analysis of the influent and effluent characteristics (COD, BOD, N, P, microorganisms, TSS, etc.) for each compartment monitored in the first period of plant operations. The pilot plant consists of two experimental lines, each characterised by a first and second treatment stage. The effluents of the first stages are divided into three different second-stage basins. The plant demonstrated high removal of nutrients, a good buffering capacity and a reasonable reduction of microorganisms after only a limited number of months of operation. Continued monitoring and comparison of the different constructed wetland strategies is providing interesting information for future designs and operation.

Enhanced Denitrification by a Hybrid HF-FWS Constructed Wetland in a Large-Scale Wastewater Treatment Plant

(*u ) Corresponding author: e-mail address: masi@iridra.com Abstract The municipal centralized treatment plant (a classic activated sludge technology) receiving the wastewater produced by the municipality of Jesi (Ancona province, Central Italy), was upgraded in 2002. A new “nitrification–denitrification” compartment and a hybrid constructed wetland (CW) were added to the system to enhance denitrification and provide final treatment polishing. The whole system treats about 19,000 m day (more than 60,000 PE) and a part of the effluent is reused in a nearby industrial area. All the new sections have been provided with an online monitoring system, in order to reduce as much as possible the energy consumption for the denitrification process, and relying more on the final wetland stage whenever it obtains sufficient treatment levels. The upgraded wastewater treatment plant has been operating since January 2003, and after the first year of operation, good development of the macrophyte communities has been observed. The hybrid CW system consists of an initial sedimentation pond (volume of 2,000 m), a 1 ha horizontal subsurface flow system (HF) second stage, and 5 ha free water system (FWS) as a final component. It has taken almost 18 months since the CW start-up for denitrification to occur at considerable levels. Nitrates removal rates ranged from 25% to 98% during the hottest period of the year.

Upflow anaerobic sludge blanket and aerated constructed wetlands for swine wastewater treatment: a pilot study

Swine wastewater management is often affected by two main issues: a too high volume for optimal reuse as a fertilizer and a too high strength for an economically sustainable treatment by classical solutions. Hence, an innovative scheme has been tested to treat swine wastewater, combining a low cost anaerobic reactor, upflow anaerobic sludge blanket (UASB), with intensified constructed wetlands (aerated CWs) in a pilot scale experimental study. The swine wastewater described in this paper is produced by a swine production facility situated in North Italy. The scheme of the pilot plant consisted of: (i) canvas-based thickener; (ii) UASB; (iii) two intensified aerated vertical subsurface flow CWs in series; (iv) a horizontal flow subsurface CW. The influent wastewater quality has been defined for total suspended solids (TSS 25,025 ± 9,323 mg/l), organic carbon (chemical oxygen demand (COD) 29,350 ± 16,983 mg/l), total reduced nitrogen and ammonium (total Kjeldahl nitrogen (TKN) 1,783 ± 498 mg/l and N-NH4+ 735 ± 251 mg/l) and total phosphorus (1,285 ± 270 mg/l), with nitrates almost absent. The overall system has shown excellent performances in terms of TSS, COD, N-NH4+ and TKN removal efficiencies (99.9%, 99.6%, 99.5%, and 99.0%, respectively). Denitrification (N-NO3- effluent concentration equal to 614 ± 268 mg/l) did not meet the Italian quality standards for discharging in water bodies, mainly because the organic carbon was almost completely removed in the intensified CW beds.