Chemical composition, nutrient-balancing and biological treatment of hand washing greywater

On-site biological hand washing water treatment can improve global access to safe hand washing water, but requires a thorough understanding of the chemical composition of the water to be treated, and an effective treatment strategy. This study first presents a detailed characterization of the individual inputs to hand washing water. We demonstrate (i) that soap is likely the most significant input in hand washing water, representing similar to 90% of mass loading, and (ii) that inputs to hand washing water have low concentrations of biologically-essential macro- and micro-nutrients (nitrogen, phosphorus, potassium, copper, zinc, molybdenum and cobalt) with respect to carbon, which may impair biological carbon removal. This study next formulates a recipe that recreates a representative composition of hand washing water and develops a procedure to identify and supplement nutrients in which this recipe is estimated to be deficient. Batch testing of the nutrient-supplemented hand washing water with an inoculum of planktonic bacteria demonstrated improved assimilable organic carbon removal (99% vs. 86% removal) and produced lower final dissolved organic carbon concentrations (1.7 mg(c)/L vs. 3.5 mg(c)/L) compared to realistic (nutrient-deficient) washing water. Supplementing nutrients did promote cell growth (50x higher final total cell count). Full-scale testing in a biologically activated membrane bioreactor (BAMBi) system treating 75 L/day of nutrient -supplemented hand washing water showed that long-term operation (100 days) can deliver effective carbon removal (95%) without detrimental fouling or other disruptions caused by cell growth. This work demonstrates that biological treatment in a BAMBi system, operated with appropriate nutrient-balancing offers an effective solution for decentralized treatment of light greywater. (C) 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.

Biofuel production from microalgae by hydrothermal processing

Rizlan Bernier-Latmani, Gabriela Anca Haiduc, Christian Ludwig, Jean-Paul Schwitzguebel, Frédéric Vogel

Introduction: Microalgae cultures represent an attractive source of biomass for biofuel and chemicals production since they can have higher energy yields per area than conventional biomass crops and can be grown on marginal land using waste, saline, or brackish water. Their use can thus avoid the food-fuel competition for land, resulting in major economic and social benefits. At the present stage however, major developments are needed for making microalgae-to-biofuels processes technologically and economically feasible. One substantial technical challenge is the development of cost-effective processes for efficient conversion of microalgae biomass to biofuels. Our research aims to study the production of biodiesel and of bio-Synthetic Natural Gas (SNG) from microalgae. Experimental: Several species of microalgae are grown at laboratory scale to compare the yield of biomass and lipid production. In addition to the potential use of oil for biodiesel production, we are currently working towards demonstrating the technical and economical feasibility of an innovative process, “SunCHem”, for SNG production via hydrothermal (HT) processing of microalgae. The process is envisioned as a closed-cycle with respect to nutrients, water and CO2, that are separated and reused for microalgae growth, resulting in unprecedented energy efficiency for both algae and fuel production. Results and Discussion: Before the feasibility of the process can be demonstrated several key challenges stemming from its closed-nature need to be tackled. One major challenge is the recycling of nutrient-rich effluents, which upon continuous operation might become enriched in potential toxicants that in turn affect the growth of algae. We demonstrated that the presence of trace metals (Ni, Cr) in the recycled effluent as a result of reactor wall corrosion and catalyst leaching resulted in adverse effect on the growth of microalgae. The effect was directly proportional to the heavy metal concentration, and for the highest concentrations tested (Ni 25 ppm or Cr 5 ppm) complete inhibition of cell growth was observed. It is known that algae, like many other organisms, can adapt to extreme environments, including those with heavy metal contamination, and the resulting mutants are better suited to survive under those particular conditions. In the framework of the present COST Action we will investigate the potential of developing and using metal-tolerant mutant microalgae as a biomass source for the SunCHem process. Experiments will be undertaken to develop Cr- and Ni- tolerant mutants by selective breeding and then comparing the mutants and the wild-type strains for their sensitivity to the heavy-metal contaminated HT effluent and the resulting biomass yields obtained in each case. It is hoped that the use of the metal-tolerant mutants will contribute to the cost-effectiveness of the process by offering an efficient alternative to the use of the more costly setups otherwise needed for effluent clean-up, thus providing a way to avoid the reduction in the biomass yield upon continuous operation of the SunCHem process. Conclusions: Another aspect of utmost importance is the evaluation of the availability for algae of the nutrients contained in the recycled effluents from the process. To this end, microalgae growth experiments will be performed using as sole nutrient source the salt brine delivered from the HT step. The biomass composition with and without recycled input from the hydrothermal process will be characterized. These tests will provide information on the recycling efficiency and speciation of nutrients and will help to identify potential nutrient management issues. If there is significant loss of a given key nutrient, it will have to be replaced in the bioreactor. A candidate for loss through volatilization could be N. Subsequent studies will explore the role of growth media and especially that of nutrients such as N, P, and minerals. Algae growth experiments will be performed using different synthetic media compositions and varying nutrient levels to assess the tolerance of algae to changes in nutrient level and quality. The issue is of special relevance as the possibility of recycling and reusing all the nutrients, including N and P, is a sine qua non condition for closing the loop in the process.

2010

Enhanced biofuel production from microalgae by adding CO2 to stimulate lipid biosynthesis (biodiesel) and by hydrothermal processing (syngas)

Gabriela Anca Haiduc, Christian Ludwig, David Pauli, Jean-Paul Schwitzguebel, Frédéric Vogel

Introduction: Microalgae cultures represent an attractive source of biomass for biofuel and chemicals production since they can have higher energy yields per area than conventional biomass crops and can be grown on marginal land using waste, saline, or brackish water. Their use can thus avoid the food-fuel competition for land, resulting in major economic and social benefits. At the present stage however, major developments are needed for making microalgae-to-biofuels processes technologically and economically feasible. One substantial technical challenge is the development of cost-effective processes for efficient conversion of microalgae biomass to biofuels. Our research aims to enhance the production of biodiesel and of bio-Synthetic Natural Gas (SNG) from microalgae. Experimental : Several species of microalgae are grown at laboratory scale to compare the yield of biomass and lipid production. In addition to the potential use of oil for biodiesel production, we are currently working towards demonstrating the technical and economical feasibility of an innovative process, “SunCHem”, for SNG production via hydrothermal (HT) processing of microalgae. The process is envisioned as a closed-cycle with respect to nutrients, water and CO2, that are separated and reused for microalgae growth, resulting in unprecedented energy efficiency for both algae and fuel production. The possible effect of increasing injection of CO2 in the growth medium is under investigation, with the aim to mitigate CO2 and enhance biomass production. Results and Discussion: Before the feasibility of the process can be demonstrated several key challenges stemming from its closed-nature need to be tackled. One major challenge is the recycling of nutrient-rich effluents, which upon continuous operation might become enriched in potential toxicants that in turn affect the growth of algae. We demonstrated that the presence of trace metals (Ni, Cr) in the recycled effluent as a result of reactor wall corrosion and catalyst leaching resulted in adverse effect on the growth of microalgae. The effect was directly proportional to the heavy metal concentration, and for the highest concentrations tested (Ni 25 ppm or Cr 5 ppm) complete inhibition of cell growth was observed. It is known that algae, like many other organisms, can adapt to extreme environments, including those with heavy metal contamination, and resulting mutants or strains should be more suited to survive under those particular conditions. The potential of developing and using metal-tolerant mutant microalgae as a biomass source for the SunCHem process is under investigation. Experiments are undertaken to develop Cr- and Ni- tolerant mutants by selective breeding and then comparing the mutants and the wild-type strains for their sensitivity to the heavy-metal contaminated HT effluent and the resulting biomass yields obtained in each case. It is hoped that the use of the metal-tolerant mutants or strains will contribute to the cost-effectiveness of the process by offering an efficient alternative to the use of the more costly setups otherwise needed for effluent clean-up, thus providing a way to avoid the reduction in the biomass yield upon continuous operation of the SunCHem process. On the other hand, metal-tolerant and accumulating microalgae could be used to treat industrial wastewater. Conclusions: Another aspect of utmost importance is the evaluation of the availability for algae of the nutrients contained in the recycled effluents from the process. To this end, microalgae growth experiments will be performed using as sole nutrient source the salt brine delivered from the HT step. The biomass composition with and without recycled input from the hydrothermal process will be characterized. These tests will provide information on the recycling efficiency and speciation of nutrients and will help to identify potential nutrient management issues. If there is significant loss of a given key nutrient, it will have to be replaced in the bioreactor. A candidate for loss through volatilization could be N. Subsequent studies will explore the role of growth media and especially that of nutrients such as N, P, and minerals. Algae growth experiments will be performed using different synthetic media compositions and varying nutrient levels to assess the tolerance of algae to changes in nutrient level and quality. The issue is of special relevance as the possibility of recycling and reusing all the nutrients, including N and P, is a sine qua non condition for closing the loop in the process.

2010

Soil nutrient availability alters tree carbon allocation dynamics during drought

Leonie Corine Schönbeck

Drought alters allocation patterns of carbon (C) and nutrients in trees and eventually impairs tree functioning. Elevated soil nutrient availability might alter the response of trees to drought. We hypothesize that increased soil nutrient availability stimulates root metabolism and carbon allocation to belowground tissues under drought stress. To test this hypothesis, we subjected three-year-old Pinus sylvestris saplings in open-top cambers during two subsequent years to drought using three different water treatments (100%, 20% and 0% plant available water in the soil) and two soil nutrient regimes (ambient and nitrogen-phosphorus-potassium (N-P-K) fertilization corresponding to 5 g N/m2/yr) and released drought thereafter. We conducted a 15N and 13C labelling experiment during the peak of the first-year drought by injecting 15N labelled fertilizer in the soil and exposing the tree canopies to 13C labelled CO2. The abundance of the N and C isotopes in the roots, stem and needles was assessed during the following year. C uptake was slightly lower in drought stressed trees, and extreme drought inhibited largely the N uptake and transport. Carbon allocation to belowground tissues was decreased under drought, but not in combination with fertilization. Our results indicate a potential positive feedback loop, where fertilization improved the metabolism and functioning of the roots, stimulating C allocation to belowground tissues. This way, soil nutrients compensated for drought-induced loss of root functioning, mitigating drought stress of trees.

2020

Biofuel production from microalgae by hydrothermal processing

Rizlan Bernier-Latmani, Gabriela Anca Haiduc, Christian Ludwig, Jean-Paul Schwitzguebel, Frédéric Vogel

2010

Enhanced biofuel production from microalgae by adding CO2 to stimulate lipid biosynthesis (biodiesel) and by hydrothermal processing (syngas)

Gabriela Anca Haiduc, Christian Ludwig, David Pauli, Jean-Paul Schwitzguebel, Frédéric Vogel

Introduction: Microalgae cultures represent an attractive source of biomass for biofuel and chemicals production since they can have higher energy yields per area than conventional biomass crops and can be grown on marginal land using waste, saline, or brackish water. Their use can thus avoid the food-fuel competition for land, resulting in major economic and social benefits. At the present stage however, major developments are needed for making microalgae-to-biofuels processes technologically and economically feasible. One substantial technical challenge is the development of cost-effective processes for efficient conversion of microalgae biomass to biofuels. Our research aims to enhance the production of biodiesel and of bio-Synthetic Natural Gas (SNG) from microalgae. Experimental : Several species of microalgae are grown at laboratory scale to compare the yield of biomass and lipid production. In addition to the potential use of oil for biodiesel production, we are currently working towards demonstrating the technical and economical feasibility of an innovative process, “SunCHem”, for SNG production via hydrothermal (HT) processing of microalgae. The process is envisioned as a closed-cycle with respect to nutrients, water and CO2, that are separated and reused for microalgae growth, resulting in unprecedented energy efficiency for both algae and fuel production. The possible effect of increasing injection of CO2 in the growth medium is under investigation, with the aim to mitigate CO2 and enhance biomass production. Results and Discussion: Before the feasibility of the process can be demonstrated several key challenges stemming from its closed-nature need to be tackled. One major challenge is the recycling of nutrient-rich effluents, which upon continuous operation might become enriched in potential toxicants that in turn affect the growth of algae. We demonstrated that the presence of trace metals (Ni, Cr) in the recycled effluent as a result of reactor wall corrosion and catalyst leaching resulted in adverse effect on the growth of microalgae. The effect was directly proportional to the heavy metal concentration, and for the highest concentrations tested (Ni 25 ppm or Cr 5 ppm) complete inhibition of cell growth was observed. It is known that algae, like many other organisms, can adapt to extreme environments, including those with heavy metal contamination, and resulting mutants or strains should be more suited to survive under those particular conditions. The potential of developing and using metal-tolerant mutant microalgae as a biomass source for the SunCHem process is under investigation. Experiments are undertaken to develop Cr- and Ni- tolerant mutants by selective breeding and then comparing the mutants and the wild-type strains for their sensitivity to the heavy-metal contaminated HT effluent and the resulting biomass yields obtained in each case. It is hoped that the use of the metal-tolerant mutants or strains will contribute to the cost-effectiveness of the process by offering an efficient alternative to the use of the more costly setups otherwise needed for effluent clean-up, thus providing a way to avoid the reduction in the biomass yield upon continuous operation of the SunCHem process. On the other hand, metal-tolerant and accumulating microalgae could be used to treat industrial wastewater. Conclusions: Another aspect of utmost importance is the evaluation of the availability for algae of the nutrients contained in the recycled effluents from the process. To this end, microalgae growth experiments will be performed using as sole nutrient source the salt brine delivered from the HT step. The biomass composition with and without recycled input from the hydrothermal process will be characterized. These tests will provide information on the recycling efficiency and speciation of nutrients and will help to identify potential nutrient management issues. If there is significant loss of a given key nutrient, it will have to be replaced in the bioreactor. A candidate for loss through volatilization could be N. Subsequent studies will explore the role of growth media and especially that of nutrients such as N, P, and minerals. Algae growth experiments will be performed using different synthetic media compositions and varying nutrient levels to assess the tolerance of algae to changes in nutrient level and quality. The issue is of special relevance as the possibility of recycling and reusing all the nutrients, including N and P, is a sine qua non condition for closing the loop in the process.

2010