María Cruz García-González

• PhD
• Professor (Assistant) at University of Valladolid.

The intensification and specialization of global agriculture has led to a nutrient surplus resulting in regional environmental issues such as eutrophication and loss of biodiversity due to nutrient accumulation. Addressing these challenges requires a shift towards regional nutrient circularity, inspired by the principles of a circular economy, to c...

The use of anaerobic fermentation to produce volatile fatty acids (VFAs) is an environmentally sustainable alternative for cheese whey (CW) valorization. This study evaluates the effect of pH control on the conversion of organic matter to VFAs from CW and assesses VFA recovery using a novel approach based on gas-permeable membranes. VFA bioconversi...

Halophytes are gaining considerable attention due to their applications in saline agriculture, phytoremediation, medicine, and secondary metabolite production. This study investigated the bioactive components present in Silene uniflora (sea campion) hydromethanolic extract, and their antimicrobial activity was evaluated both in vitro and ex situ ag...

Nutrient recovery from the agri-food sector waste is an increasingly recognized option within the framework of the bioeconomy. Membrane technologies and chemical precipitation are among the best valued options for their economic and practical feasibility. In this study, the combination of gas-permeable membrane (GPM) technology for the recovery of...

Botrytis cinerea is the most harmful postharvest disease of table grapes. Among the strategies that can be envisaged for its control, the use of coatings based on natural products is particularly promising. The study presented herein focuses on the assessment of the antagonistic capacity of two Streptomyces species and their culture filtrates again...

Anaerobic digestion (AD) has been largely studied and it is widely applied for manure treatment in Europe, although its implementation is scarce in Spain and Portugal. The major benefit of AD is the production of renewable energy in the form of methane and digestate that is used as fertilizer, as it contains N, P and K. The aim of this work was to...

The technology of gas-permeable tubular membranes (GPMs) is promising in reducing ammonia emissions from livestock manure, capturing NH3 in an acidic solution, and obtaining final products suitable for valorization as fertilizers, in line with the principles of the circular economy. This study aimed to evaluate the performance of several e-PTFE mem...

The worldwide increment of food waste requires innovative management solutions, aligned with sustainability, energy, and food security. Anaerobic digestion (AD), followed by nutrient recovery, may be considered an interesting approach. This study proposed a co-digestion of apple pomace (AP) with swine manure (SM) to study the effect of different pr...

The manufacture of mineral N fertilisers by the Haber–Bosch process is highly energy-consuming. The nutrient recovery technologies from wastes through low-cost processes will improve the sustainability of the agricultural systems. This work aimed to assess the suitability of the gas-permeable membrane (GPM) technology to recover N from an anaerobic...

Gas-permeable membrane (GPM) technology is a novel alternative to reduce N content in wastewater while recovering N in the form of an ammonium salt solution that can be used as fertilizer. This work aims to elucidate the effects of three operational conditions on the performance of GPM technology for ammonia recovery in batch conditions using synth...

The objective of this work was to characterize agricultural and livestock holdings in the regions of Castilla and León (Salamanca and Zamora) in Spain and the Centro Region in Portugal. In order to carry out this work, the available statistical databases were used, according to the themes related to the social, economic, environmental and technolog...

The application of new technologies in the agro-industrial sector is needed to close the loop of the nutrient cycle in the food chain. The aim of this work is to study the feasibility of the combination of two nutrient recovery technologies. In a first step, the novel gas-permeable membrane technology recovers N from the wastewater as an ammonium s...

The gas-permeable membrane (GPM) technology is one of the most novel techniques capable of minimizing ammonia (NH3) emissions associated to wastewaters, while recovering nitrogen as nutrient. This study conducted for the first time a life cycle assessment of this technology (treatment scenario), to compare the environmental trade-offs with the conv...

The reduction and recovery of nitrogen (N) from anaerobically digested manure (digestate) is desirable to mitigate N-related emissions, mainly ammonia and nitrate, derived from digestate land application in nutrient-saturated zones. This work reports the results of a gas-permeable membrane (GPM) pilot-scale plant to recover ammonia from digestate i...

Agro-industrial waste represents a major challenge for the environment. Among these, the processing of peppers generates a large amount of waste, so the search for new ways to valorise this waste is crucial. This work aims to assess the use of pepper waste for methane production with swine manure. During this study, anaerobic co-digestion was evalu...

The recovery of valuable materials from waste fits the principle of circular economy and sustainable use of resources, but contaminants in the waste are still a major obstacle. This works proposes a novel approach to recover high-purity phosphorus (P) and nitrogen (N) from digestate of municipal solid waste based on the combination of two independe...

In feedstocks containing high ammonia (NH3) concentration, removal of the NH3 during the anaerobic digestion (AD) process can improve AD process performance. In the present study, the effect of NH3 removal using gas-permeable membrane (GPM) technology on AD process performance and biogas production was investigated using swine manure feedstock. Bat...

Gas-permeable membranes technology presents a high potential for nitrogen (N) recovery from wastewaters rich in ammonia (NH3). The EU project Ammonia Trapping (AT) is aimed at transferring knowledge from the lab-scale level to on-farm pilot-scale level, using this technology to recover NH3 from livestock wastewaters. The goal of this study is to re...

This study is aimed at assessing the potential of apple pomace (AP) as a substrate for biofuel production following a biorefinery approach. Two different APs, from juice and cider production were evaluated. First, bioethanol generation was performed and its fermentation residues, together with available biobutanol fermentation residues, were studie...

This chapter reviews the alternative approaches for removing and recovering nitrogen (N) and phosphorus (P) from animal manure using both on‐farm and off‐farm management. It first provides a flow diagram on alternative approaches to traditional land application of manures, and shows desirable characteristics of the recovered products. The chapter t...

Today, agro-industry is a key economic sector worldwide with a large associated generation of wastewaters. These wastewaters entail a hazard to the environment and a waste of valuable organic matter and nutrients. The use of microalgae to support an efficient and low cost treatment of agro-industrial wastewaters along with a sustainable resource re...

Wastewater generation has concomitantly increased with the growth of world human population in the last century. The uncontrolled discharge of wastewater may result in serious social, environmental and health problems. At the same time, the use of microalgal-based systems has been widely studied for a variety of residual effluents treatment since t...

Gas-permeable membrane technology is a new strategy to minimize ammonia losses from manure, reducing pollution and recovering N in the form of an ammonium salt fertilizer. In this work, a new operational configuration to recover N using the gas-permeable membrane technology from swine manure was tested in a semi-continuous mode. It treated swine ma...

Nowadays, it is a well-accepted fact that greenhouse gases (GHG) contribute to the global warming of the planet and that they are a very real and very serious threat to the whole world. It is estimated that 10% of total GHG emitted is from sources in the agricultural sector and over 3% from waste management. Most countries agreed to reduce GHG emis...

Reducing NH3 emissions together with nutrient recycling are two major concerns in European agriculture nowadays. Among the diverse technologies to recover nitrogen from livestock wastes (i.e. reverse osmosis, air stripping, zeolite adsorption and struvite precipitation), gas-permeable membrane is one of the lowest in energy consumption (0.18 kWh kg...

Anaerobic digestion of wastes for renewable energy production is well developed in Europe but, the situation is very different from one country to another. Germany and Italy are by far the main producer countries, leaving behind countries like Spain and Portugal, which have significant potential but do not implement this technology for the treatmen...

In the last decade substantial innovation in feeds has led to a significant reduction in fishmeal inclusion rates in feed for aquaculture. Nevertheless, to maintain the current growth of aquaculture, the demand of nutrient will increase at the same rate. So finding a sustainable alternative protein source to replace fish meal in fish feed continues...

The safe recycling of organic wastes such as the nutrients obtained from agriculture activities is a relevant aspect of the “One Health” strategy, a worldwide initiative including all aspects of health care for humans and animals, as well as aspects related to the conservation and development of the environment. It represents an important opportuni...

This study was aimed at evaluating gas-permeable membrane technology (N-recovery) coupled with anaerobic digestion (AD) for the treatment of swine manure (SM). For this purpose, 66.7% of the initial total ammoniacal nitrogen (TAN) contained in centrifuged SM was first recovered by an e-PTFE gas-membrane as an ammonium sulfate solution. The resultan...

The recovery of proteins from microalgae is gaining special attention for animal feed applications especially for fish feed, as the costs of aquaculture feeds represent between 40 and 70% of the costs of the fish produced. Besides, the use of pig manure to produce microalgal biomass could contribute to manure bioremediation and therefore to reduce...

The upsurge in fungal diseases that cause grapevine wood rot in young and adult plants remains a major concern for the wine sector. Since pruned vine shoots act as a reservoir of these fungi, there is a need for sanitization methods that can prevent their spread, avoiding plant reinfection. In this work, the effectiveness of dry heat treatments for...

Gas-permeable membrane technology is useful to recover ammonia (NH3) from liquid manures. In this study, phosphorus (P) recovery via MgCl2 precipitation was enhanced by combining it with NH3 recovery through gas-permeable membranes. Anaerobically digested swine wastewater containing approximately 2300 mg NH4⁺-N L⁻¹ and 450 mg P L⁻¹ was treated usin...

Enteric pathogens from biofertilizer can accumulate in the soil, subsequently contaminating water and crops. We evaluated the survival, percolation and leaching of model enteric pathogens in clay and sandy soils after biofertilization with swine digestate: PhiX-174, mengovirus (vMC0), Salmonella enterica Typhimurium and Escherichia coli O157:H7 wer...

In this study, eight different manure treatment plants were monitored. The plants were four on-farm and four centralized treatment plants, all of them at full-scale level. Assess­ment includes a total of seven pre-treatment and process units as follows: mechanical separa­tion, with and without coagulant and flocculant addition, pasteurization, nitr...

In this study, eight different manure treatment plants were monitored. The plants were four on-farm and four centralized treatment plants, all of them at full-scale level. Assessment includes a total of seven pre-treatment and process units as follows: mechanical separation , with and without coagulant and flocculant addition, pasteurization, nitri...

Nitrogen (N) can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate) has the highest N content in ammonia form (NH 3). It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ) and to mitigate NH 3 emissions during N...

Nitrogen (N) can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate) has the highest N content in ammonia form (NH 3). It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ) and to mitigate NH 3 emissions during N...

After the ban on sodium arsenite, waste management alternatives to the prevalent burning method, such as the hygienization and biodegradation in solid phase by composting, are required for the pruned material from grapevines affected by various fungi. In this work the dynamics of a fungus associated with vine decay (Diplodia seriata) during the com...

The use of manure as agricultural amendment is increasing the release of steroid hormones into the environment. While most research in this field has focused on estrogenic phenomena, less attention has been paid to androgenic substances. Here we assessed androgenic activity in broiler manure using in vitro approaches based on cells stably transfect...

The use of propidium monoazide (PMA) coupled with real-time PCR (RT-qPCR or qPCR for RNA or DNA viruses, respectively) was assessed to discriminate infectious enteric viruses in swine raw manure, swine effluent from anaerobic biodigester (AB) and biofertilized soils. Those samples were spiked either with infectious and heat-inactivated human adenov...

Gas-permeable membrane technology is useful to recover ammonia from manure. In this study, the technology was enhanced using aeration instead of alkali chemicals to increase pH and the ammonium (NH4(+)) recovery rate. Digested effluents from covered anaerobic swine lagoons containing 1465-2097mgNH4(+)-NL(-1) were treated using submerged membranes (...

Nitrogen recovery from swine manure was investigated using gas-permeable membranes. The process involved a continuous recirculation of an acidic solution through a gas-permeable membrane submerged in manure. Ammonia from manure was concentrated in the acidic solution increasing its pH, while pH decreased in manure. In the first set of experiments,...

presentation at Int’l. Symp. on Air Quality and Waste Management for Agriculture, Broomfield, CO.

The potential of algal–bacterial symbiosis for the removal of carbon, nitrogen and phosphorus from five agro-industrial wastewaters was investigated in enclosed batch biodegradation tests using a mixed microalgae consortium and activated sludge as model microorganisms. The target wastewaters were obtained from potato processing (PW), fish processin...

Las enfermedades de la madera de la vid en España, como en el resto de países productores de vino, alcanzan todas las áreas vitícolas con daños apreciables. El objetivo del trabajo fue utilizar el compostaje como control fitosanitario eliminando los restos de poda y los sarmientos que, dejados en las parcelas, constituyen un reservorio de microorga...

This work evaluates the efficiency of different advanced oxidation processes (Fenton method, O3, H2O2 and O3/H2O2) for removing total COD (TCOD) and colour from biologically pre-treated swine manure. The Fenton process with a dosage of 100mgL(-1) of Fe(2+) and 800mgL(-1) of H2O2 resulted in about 78% TCOD and 96% colour reductions at an initial pH=...

Background Microalgae-based technologies have emerged as a promising approach for simultaneous wastewater treatment and fish food production able to overcome the main limitations in the aquaculture sector. The current study focused on the mechanisms of carbon and nutrient removal from fish farm and domestic wastewaters in a 180 L outdoors pilot hig...

The costs of fertilizers have rapidly increased in recent years, especially nitrogen fertilizer such as anhydrous ammonia which is made from natural gas. Thus, new treatment technologies for abatement of ammonia emissions in livestock operations are being focused on N recovery in addition to the N removal. Nitrogen recovery from swine manure was in...

Anaerobic digestion of livestock wastes (swine manure (SM) and poultry litter (PL)) and vegetable processing wastes (VPW) mixtures was evaluated in terms of methane yield, volatile solids removal and lignocellulosic material degradation. Batch experiments were performed with 2% VS (volatile solids) to ensure complete conversion of TVFAs (total vola...

Microalgal-based systems are currently receiving increasing attention due to their ability to treat wastewater, whilst also providing a high-added value product in the form of biomass. The potential of the microalgae Chlorella sorokiniana and Spirulina platensis to use fish processing wastewater as a growth medium in symbiosis with aerobic bacteria...

A wastewater treatment process and systems were developed to extract and concentrate phosphates from livestock wastewater. The research was conducted over a 10-year period and went from initial bench studies to pilot module development to full-scale demonstrations of the phosphorus module on swine farms and current licensing and commercialization b...

The effect of adding vegetable waste as a co-substrate in the anaerobic digestion of swine manure was investigated. The study was carried out at laboratory scale using semi-continuous stirred tank reactors working at 37 °C. Organic loading rates (OLRs) of 0.4 and 0.6 g VS L−1 d−1 were evaluated, corresponding to hydraulic retention times (HRTs) of...

The purpose of this study was the evaluation of chitosan flocculation ability to recover microalgal-bacterial biomass from an open pond treating fish processing wastewater. A second order factorial design followed by response surface methodology was applied to estimate the effect of chitosan concentration and agitation speed on flocculation activit...

Most of the organic nutrient elements (nitrogen and phosphorus) and carbon compounds in liquid swine are contained in fine suspended particles. Flocculation treatment with polyacrylamide (PAM) followed by screening is one the best methods to separate the liquid fraction from the solid fraction in swine manure, and thus to eliminate nutrient element...

Soil has an important role in the greenhouse effect as a net source or net sink of greenhouse gases. This study compared CO 2 emission from broiler poultry manure (PMB) and hen poultry manure (PMH) in two different soils. A laboratory experiment was conducted to evaluate the decomposition of poultry manure by analysing carbon mineralisation. Jars w...

Two photobioreactors inoculated with microalgae from a lagoon containing aerobically treated swine slurry and with sludge from a membrane submerged bioreactor treating winery wastewater were established to treat fish processing wastewater (FPW) at 23 and 31 °C, respectively. The hydraulic retention time (HRT) was decreased in the photobioreactors f...

In an attempt to propose an integrated system to treat swine manure, the codigestion of this residue and microalgal biomass was evaluated. Response surface methodology showed that chemical oxygen demand/volatile solids (COD/VS) and COD algae supplement presented a significant effect on methane yield. Second-order polynomial model fitted quite well...

Deposit of useful microorganisms in culture collections requires long-term preservation and successful reactivation techniques. The goal of this study was to develop a simple preservation protocol for the long-term storage and reactivation of the anammox biomass. To achieve this, anammox biomass was frozen or lyophilized at two different freezing t...

This work examines the methane production potential for the anaerobic co-digestion of swine manure (SM) with winery wastewater (WW). Batch and semi-continuous experiments were carried out under mesophilic conditions. Batch experiments revealed that the highest specific methane yield was 348 mL CH(4)g(-1) COD added, obtained at 85.4% of WW and 0.7 g...

There is great controversy regarding the best substrate (fresh or anaerobically digested swine slurry) for the development of microalgae-bacteria consortia. This study aims to elucidate the best substrate by assessing biomass productivity, microorganism predominance, and their ability for organic matter removal. In addition to the different substra...

Anaerobic digestion of livestock wastes with carbon rich residues was studied. Swine manure and poultry litter were selected as livestock waste, and vegetable processing waste was selected as the rich carbon source. A Central Composite Design (CCD) and Response Surface Methodology (RSM) were employed in designing experiments and determine individua...

Microalgae systems are currently being researched due to their ability to mitigate carbon dioxide emissions while obtaining a value-added product in the form of biomass. This paper elucidates the ability of microalgal–bacteria consortia for the conversion of organic matter contained in anaerobically digested swine slurry into biomass organic carbon...

Four open ponds inoculated with microalgae-bacteria consortium treating different swine slurries (fresh and anaerobically digested) were evaluated in terms of nitrogen transformation under optimal and real conditions of temperature and illumination. Ammonium complete depletion was not achieved. Ponds operated under real conditions presented lower a...

The purpose of the study was comparison of two configurations of photobioreactors an open-type photobioreactor open to atmosphere and a tubular type photobioreactor closed to the atmosphere. Organic matter was fairly removed under both configurations at 50-60% and biomass carbon content on dry weight basis accounted for 45%. Both configurations wer...

Two green microalgae (Scenedesmus obliquus and Chlorella sorokiniana), one cyanobacterium (Spirulina platensis), one euglenophyt (Euglena viridis) and two microalgae consortia were evaluated for their ability to support carbon, nitrogen and phosphorous removal in symbiosis with activated sludge bacteria during the biodegradation of four and eight t...

Different uncomposted and composted poultry manure types (laying hen and broiler), mixed at increasing rates (0, 25, 50, 75 and 100%) with two amended peat substrates, were tested to study the phytotoxicity using the cress ( Lepidium sativum, L. ) germination method. The results showed that composting generally reduced the phytotoxicity of the manu...

The anammox process, under different organic loading rates (COD), was evaluated using a semi-continuous UASB reactor at 37 degrees C. Three different substrates were used: initially, synthetic wastewater, and later, two different pig manure effluents (after UASB-post-digestion and after partial oxidation) diluted with synthetic wastewater. High amm...

The aim of this study was to determine the effectiveness of natural flocculants to reduce solids and nutrient loads in dairy cow wastewater using solid-liquid separation; chitosan was used as a model. Its use efficiency and optimum application rate were determined using flushed dairy cow manure of varied strengths - 0.4%, 0.8%, 1.6%, and 3.2% total...

Pig manure treatments and characteristics change from a country or region to another according to climatology, breeding types, land availability, farm characteristics and production, watering and feeding systems, waste collection, etc. In this work, raw manure and some manure treatment systems were characterized in different farms along Castilla y...

In this article, we describe improvement of a manure treatment system without a lagoon through implementation of a concept of simultaneous separation of solids. The original system consisted of three basic processes in series: solid-liquid separation of raw swine manure (SM) using cationic polyacrylamide (PAM), subsequent treatment of liquid throug...

Poultry droppings, product of the fermentation of poultry excrements, are one of the organic residues most used nowadays in agriculture as an alternative to the organic traditional fertilization with classic manure. A physiochemical study has been carried out with residues proceeding from eleven poultry farms, representing two types of predominant...

The traditional housing of intensive broiler production in Castilla y Leon (Spain) is a closed building construction of concrete or wood with natural light or windowless with a light system. Depending on the season of the year facilities are naturally or force-ventilated. Broilers are kept on bedding material spread over the entire house floor area...

Intensive poultry farms may be detrimental to the natural environment through the polluting of this same environment. This waste has a high concentration of organic matter that can be used to advantage. One of the important factors affecting the successful use of poultry manure for agriculture purposes is stability /maturity. Applications of unstab...

Organic polymers are useful to increase separation of suspended solids and carbon compounds from liquid swine manure, but experiences with dairy manure are limited. In this experiment, two polymers, a synthetic polyacrylamide (PAM) and a natural chitosan were used to increase separation of suspended solids from dairy manure. Experiments were carrie...

Research was conducted to develop process applications for anaerobic ammonium oxidation (anammox) bacteria acclimated to animal wastewater conditions using microbial immobilization techniques. In the anammox reaction, under anaerobic and autotrophic conditions, ammonium (NH4+) serves as the electron donor using nitrite (NO2-) as the electron accept...

A detailed study of a centralized manure treatment plant based on a solid-liquid separation and a combined anoxic-aerobic treatment system was carried out. Physico-chemical removal efficiency of the different units of the plant was characterized: mechanical separation, physico-chemical removal and biological treatment. The treatment plant had a goo...