Evaluation of phytodepuration intensified systems for the treatment of agricultural and livestock wastewaters

The intensification of Italian pig breeding over the years has resulted in high livestock concentrations in some parts of the country, especially in the north, increasing environmental pollutions threats. The potential environmental hazards caused by these activities regard surface water or groundwater eutrophication, emission of ammonia with consequent problems of acid deposition due to rainfall, other gases, odours, and accumulation risk of heavy metals and salts in agricultural soils. In addition, the proliferation over time of biogas plants in the livestock and agricultural field has led to a rapid and significant increase in the digestate quantities produced. The wastewaters from these activities are distributed on fields according to the European Directive (91/676 EC), which often results in an increase in the demand for available surfaces for the distribution of the effluent. However, when the land for spreading is not sufficient, other solutions must be found, that breeders solve by relocating the wastewater in other areas, incurring high transport costs. In recent years phytodepuration has proved to be of substantial interest as a system for the treatment of animal wastewater liquid fraction, representing a valid solution for its disposal when the surface area is not adequate. This work examined phytodepuration intensified systems for the treatment of agricultural and livestock wastewaters, based on low-cost solutions and reduction of the area required for treatment. The research concerned in particular the study of pilot filter systems using recycled and sustainable materials for the pretreatment of piggery wastewater and digestate, in order to purify wastewater for the phytodepuration treatment. A vertically arranged phytodepuration system was also investigated, where both wetland and halophytic plant species have been tested for the treatment of piggery wastewater. Lastly, a secondary part of this research was devoted to the hydraulics study of filters used for phosphorus treatment, and to the growth of algae on pretreated piggery wastewater to analyze the chemical removal and possible accumulation of astaxanthin. The pretreatment systems proved to be suitable for digestate and piggery wastewater depuration, with higher removal for NH4-N, COD and total N than other chemicals. The phytodepuration highlighted the potential of several plants and the weaknesses of others for the treatment of piggery wastewater, showing highest concentration abatements of NH4-N (69-99%) and lower abatements of the other chemicals

Evaluation of phytodepuration intensified systems for the treatment of agricultural and livestock wastewaters

The intensification of Italian pig breeding over the years has resulted in high livestock concentrations in some parts of the country, especially in the north, increasing environmental pollutions threats. The potential environmental hazards caused by these activities regard surface water or groundwater eutrophication, emission of ammonia with consequent problems of acid deposition due to rainfall, other gases, odours, and accumulation risk of heavy metals and salts in agricultural soils. In addition, the proliferation over time of biogas plants in the livestock and agricultural field has led to a rapid and significant increase in the digestate quantities produced. The wastewaters from these activities are distributed on fields according to the European Directive (91/676 EC), which often results in an increase in the demand for available surfaces for the distribution of the effluent. However, when the land for spreading is not sufficient, other solutions must be found, that breeders solve by relocating the wastewater in other areas, incurring high transport costs. In recent years phytodepuration has proved to be of substantial interest as a system for the treatment of animal wastewater liquid fraction, representing a valid solution for its disposal when the surface area is not adequate. This work examined phytodepuration intensified systems for the treatment of agricultural and livestock wastewaters, based on low-cost solutions and reduction of the area required for treatment. The research concerned in particular the study of pilot filter systems using recycled and sustainable materials for the pretreatment of piggery wastewater and digestate, in order to purify wastewater for the phytodepuration treatment. A vertically arranged phytodepuration system was also investigated, where both wetland and halophytic plant species have been tested for the treatment of piggery wastewater. Lastly, a secondary part of this research was devoted to the hydraulics study of filters used for phosphorus treatment, and to the growth of algae on pretreated piggery wastewater to analyze the chemical removal and possible accumulation of astaxanthin. The pretreatment systems proved to be suitable for digestate and piggery wastewater depuration, with higher removal for NH4-N, COD and total N than other chemicals. The phytodepuration highlighted the potential of several plants and the weaknesses of others for the treatment of piggery wastewater, showing highest concentration abatements of NH4-N (69-99%) and lower abatements of the other chemicals.Il processo di intensificazione dell’allevamento suino in Italia ha portato negli anni ad un alta concentrazione di animali in alcune parti del paese, specialmente al nord, accrescendo i rischi di inquinamento ambientale. I potenziali danni sull’ambiente causati da queste attività riguardano l’eutrofizzazione delle acque superficiali e sotterranee, le emissioni di ammoniaca con conseguenti problemi di deposizioni acide in seguito a precipitazioni e di altri gas, gli odori, e il rischio di accumulo di metalli pesanti e di sali nei suoli agricoli. Inoltre la forte crescita negli ultimi anni del biogas nel settore agro-zootecnico ha generato un altrettanto rapido ed importante incremento dei quantitativi di digestato prodotto. I reflui derivanti da queste attività devono distribuiti secondo la normativa italiana (Direttiva CE 91/676), che si traduce spesso in un aumento della richiesta di superfici disponibili per la distribuzione dei reflui. Tuttavia, quando la superficie per lo spandimento è insufficiente, c’è la necessità di trovare altre soluzioni, che l’allevatore ovvia delocalizzando i reflui in altri terreni, sostenendo costi di trasporto non esigui. In questi ultimi anni la fitodepurazione si è rivelata di considerevole interesse come sistema di trattamento della frazione liquida dei reflui animali, rappresentando una valida soluzione per il loro smaltimento quando la superficie è insufficiente. Questo lavoro ha esaminato sistemi intensivi di fitodepurazione per il trattamento di reflui agro-zootecnici, basati sull’economicità e sulla riduzione della superficie per la depurazione. La ricerca ha riguardato principalmente lo studio di sistemi pilota filtranti per il pretrattamento di refluo suino e digestato, allo scopo di depurare il refluo prima del trattamento di fitodepurazione, in cui sono utilizzati materiali sostenibili e di scarto. Inoltre è stato investigato un sistema di fitodepurazione sviluppato verticalmente, ove sono state testate diverse specie vegetali per il trattamento del refluo suino. Infine, una minor parte della ricerca è stata dedicata allo studio dell’idraulica di filtri, usati per il trattamento del fosforo,e alla crescita di alghe su refluo suino pretrattato per analizzare la rimozione chimica e l’eventuale accumulo di astaxantina. I sistemi di pretrattamento si sono rivelati abili nella depurazione del digestato e del refluo suino, con maggiori abbattimenti per N-NH4, COD e TN, rispetto agli altri composti chimici. La fitodepurazione ha risaltato le potenzialità di alcune piante e le debolezze di altre per il trattamento del refluo suino, mostrando i maggiori abbattimenti di concentrazione per N-NH4 (69-99%) e più bassi per gli altri parametri chimici

Biomass production and soil organic carbon accumulation in a free water surface constructed wetland treating agricultural wastewater in North Eastern Italy

Free water surface constructed wetlands (FWSs) play an important role in wastewater pollutants removal and, at the same time, vegetated wetlands can act as carbon sinks. In this study we measured biomass production and soil carbon content variations over five years in a FWS with fluctuating hydroperiod treating agricultural drainage water to evaluate its role in the carbon dioxide cycle. During the study flooding occurred with a yearly average of 28 days. Annual dry matter production, from 2008 to 2011, ranged between 50 and 60 Mg ha 121. The highest C storage was concentrated in the belowground biomass. 83% of total belowground biomass was measured in the 0\u201320 cm soil layer. During the 2007\u20132012 period the organic carbon (OC) concentration in the 0\u201320 cm soil layer slightly increased from 12.3 to 13.1 g kg 121 and bulk density from 1.38 to 1.66 Mg m 123. In the 20\u201350 cm soil layer, monitored only in 2009 and 2012, OC concentration was lower and steady (8.8 g kg 121). The total soil C accumulation in the five years was 110.73 Mg ha 121 of equivalent CO2(eq). Given the positive C balance FWSs can be considered a CO2 sink

A simplified process of swine slurry treatment by primary filtration and Haematococcus pluvialis culture to produce low cost astaxanthin

A simplified process for treating swine slurry through primary filtration and subsequent depuration of thefiltrate with the astaxanthin-rich microalga Haematococcus pluvialis is proposed. The first step comprisesa low-cost filtration system capable of reducing 66% of ammonia, 7% of phosphorus and 19% of chemicaloxygen demand, and increasing the concentration of nitrate, being this useful for subsequent growthof the algae. The second step comprises the discontinuous cultivation of H. pluvialis in diluted filteredslurry. The optimal dilution was researched by testing undiluted and 2, 4 and 8-fold diluted filtrate. Thisstep led to a drastic reduction in macro and micronutrients concentration (up to 99% for NO3-N andNH4-N, 98% for TP and 26% for chemical oxygen demand). After H. pluvialis growth the accumulation ofastaxanthin took place for 14 d in nutrient-deprived conditions: an astaxanthin accumulation of 1.27%on a dry weight basis was measured. These results indicate the possibility to couple low-cost filtrationand microalgae production to recover nutrients from swine wastewaters and to add value by producingvaluable astaxanthin for the feed market or for an on-farm utilization as feed addictive