title: Nitrate removal from three different effluents using large-scale denitrification beds

authors: Schipper, Louis A.

subjects: denitrification

abstract: Simple technologies that remove nitrate from effluents and other point discharges need to be developed to reduce pollution of receiving waters. Denitrification beds are lined containers filled with organic carbon (typically wood chip or coarse sawdust) and are a technology that is proving promising. Water containing NO₃⁻ (treated effluent or agricultural drainage) is passed through the bed and the wood chips act as an energy source for denitrifying bacteria that convert NO₃⁻ to N gases. There are few data on the efficiency of NO₃ removal in large-scale beds. We report here NO₃⁻ removal results from three large denitrification beds with volumes of 83, 294, and 1320 m³ treating dairy shed effluent, treated domestic effluent and glasshouse effluent, respectively. Nitrate was nearly completely removed from the dairy shed effluent (annual load of 31 kg N) and domestic effluent (annual load 365 kg N). In these beds, NO₃ removal, presumably by denitrification, was limited by NO₃⁻ concentration. However, the bed treating glasshouse effluent was overwhelmed by very high NO₃⁻ concentration (about 250 g N m⁻³) and high flow rates (about 150 m³ d⁻¹) but still reduced NO₃⁻ concentration to about 150 g N m⁻³. For this bed, long-term NO₃⁻  removal was between 5 and 10 g N m⁻³ of bed material when NO₃⁻  was non-limiting and was similar to rates reported for other smaller denitrification beds. As expected, organic N, ammonium and phosphorus were not removed from any of the effluents following passage through the beds. Our results suggest that denitrification beds are a relatively inexpensive system to construct and operate, and are suitable for final treatment of a range of NO₃⁻-laden effluents.

text: Nitrate removal from three different effluents using large-scale denitrification beds Simple technologies that remove nitrate from effluents and other point discharges need to be developed to reduce pollution of receiving waters. Denitrification beds are lined containers filled with organic carbon (typically wood chip or coarse sawdust) and are a technology that is proving promising. Water containing NO₃⁻ (treated effluent or agricultural drainage) is passed through the bed and the wood chips act as an energy source for denitrifying bacteria that convert NO₃⁻ to N gases. There are few data on the efficiency of NO₃ removal in large-scale beds. We report here NO₃⁻ removal results from three large denitrification beds with volumes of 83, 294, and 1320 m³ treating dairy shed effluent, treated domestic effluent and glasshouse effluent, respectively. Nitrate was nearly completely removed from the dairy shed effluent (annual load of 31 kg N) and domestic effluent (annual load 365 kg N). In these beds, NO₃ removal, presumably by denitrification, was limited by NO₃⁻ concentration. However, the bed treating glasshouse effluent was overwhelmed by very high NO₃⁻ concentration (about 250 g N m⁻³) and high flow rates (about 150 m³ d⁻¹) but still reduced NO₃⁻ concentration to about 150 g N m⁻³. For this bed, long-term NO₃⁻  removal was between 5 and 10 g N m⁻³ of bed material when NO₃⁻  was non-limiting and was similar to rates reported for other smaller denitrification beds. As expected, organic N, ammonium and phosphorus were not removed from any of the effluents following passage through the beds. Our results suggest that denitrification beds are a relatively inexpensive system to construct and operate, and are suitable for final treatment of a range of NO₃⁻-laden effluents.

year: 2010

title: Age and growth of longfinned eels (Anguilla dieffenbachii) in pastoral and forested streams in the Waikato River basin, and in two hydro-electric lakes in the North Island, New Zealand

authors: Chisnall, Benjamin L.

subjects: biology

abstract: Growth rates of New Zealand endemic longfinned eels (Anguilla dieffenbachii) from streams in pasture and indigenous forest, and from two hydroelectric lakes (Lakes Karapiro and Matahina), were estimated by otolith examination. Habitat-specific growth was further investigated with measurement of widths of annual bands in otoliths. Longfinned eels 170-1095 mm in length ranged between 4 and 60 years old (N=252). Eels in pastoral streams grew faster (mean annual length increment ±95% CL = 24 ± 3 mm to 36 ± 7 mm) than eels in streams in indigenous forest (annual length increment 12 ± 2 mm to 15 ± 3 mm). Eels from the hydro-electric lakes had growth rates (annual length increments 19 ± 4 and 19 + 7 mm) similar to eels from pastoral streams. Otoliths of most eels showed annual band widths that indicated growth in several different habitats, corresponding to growth during upstream migration, and limited movement among adult habitats. Estimated age at marketable size (220 g) ranged between 7 and 26 years. The particularly slow growth of longfinned eels in streams in indigenous forest has considerable implications for management. The fast growth rates of eels in hydro-electric lakes provides evidence for the potential of increased eel production by stocking. The probable selective production of female eels in these lakes may be nationally important to allow enhancement of breeding stocks.

text: Age and growth of longfinned eels (Anguilla dieffenbachii) in pastoral and forested streams in the Waikato River basin, and in two hydro-electric lakes in the North Island, New Zealand Growth rates of New Zealand endemic longfinned eels (Anguilla dieffenbachii) from streams in pasture and indigenous forest, and from two hydroelectric lakes (Lakes Karapiro and Matahina), were estimated by otolith examination. Habitat-specific growth was further investigated with measurement of widths of annual bands in otoliths. Longfinned eels 170-1095 mm in length ranged between 4 and 60 years old (N=252). Eels in pastoral streams grew faster (mean annual length increment ±95% CL = 24 ± 3 mm to 36 ± 7 mm) than eels in streams in indigenous forest (annual length increment 12 ± 2 mm to 15 ± 3 mm). Eels from the hydro-electric lakes had growth rates (annual length increments 19 ± 4 and 19 + 7 mm) similar to eels from pastoral streams. Otoliths of most eels showed annual band widths that indicated growth in several different habitats, corresponding to growth during upstream migration, and limited movement among adult habitats. Estimated age at marketable size (220 g) ranged between 7 and 26 years. The particularly slow growth of longfinned eels in streams in indigenous forest has considerable implications for management. The fast growth rates of eels in hydro-electric lakes provides evidence for the potential of increased eel production by stocking. The probable selective production of female eels in these lakes may be nationally important to allow enhancement of breeding stocks.

year: 1993

title: Te mana o te wahine: Young mothers healthcare experiences in pregnancy, birth, and into motherhood

authors: Kolo, Mia Elaine

subjects: Health

abstract: In Aotearoa-New Zealand being a young mother is often associated with clinical and societal ‘risks.’ Younger women have higher rates of maternal depression and suicide, complications during birth, and their babies are more likely to be born preterm, and of smaller gestational age and weight (Perinatal and Maternal Mortality Review Committee, 2012; Te Whatu Ora - Health New Zealand, 2023b, 2023a). Research also indicates that young mothers experience stigmatisation and discrimination that they attribute to their age and/or ethnicity (Adcock, 2016; Makowharemahihi et al., 2014; Rawiri, 2007; Ware, 2019).
In discussion with researchers, discrimination was the topic that young mothers at He Puaawai Teen Parent Centre wanted to talk about. They shared a strong desire to see change in the way that doctors, nurses, and midwives service young parents and were passionate about ensuring that future young mothers had more support. Thus, in responding to their call, 22 parents, including two fathers attending (or recent school-leavers of) He Puaawai Teen Parent Centre volunteered to participate in this study. This qualitative kaupapa Māori study employed a series of wānanga, individual kōrero, and an investigator-triangulation thematic analysis. The research questions explored both the positive and negative healthcare experiences of this cohort during pregnancy, birth, and into motherhood.
The aim of this study was to listen and learn about the experiences of these young parents and co-design informational and/or educational materials to help healthcare practitioners better understand and support young mothers/parents. To spread awareness of the experiences of these young parents, the co-design materials and findings of this study were disseminated via various healthcare seminars and meetings around the Waikato region. The findings of this study contribute to previous research that revealed over the last 20 years young parents have continued to report predominantly negative experiences in their maternity journey. Participants of this study reported experiences of unsolicited judgement and advice, a general lack of manaakitanga (care, empathy, respect), communication, and support from doctors, nurses, and midwives. The relatively small number of positive experiences shared in this study emphasises the importance of manaakitanga regardless of age. An unexpected finding was the impact that receptionists had on young parents’ healthcare experiences, as the face and entry point of healthcare services.

text: Te mana o te wahine: Young mothers healthcare experiences in pregnancy, birth, and into motherhood In Aotearoa-New Zealand being a young mother is often associated with clinical and societal ‘risks.’ Younger women have higher rates of maternal depression and suicide, complications during birth, and their babies are more likely to be born preterm, and of smaller gestational age and weight (Perinatal and Maternal Mortality Review Committee, 2012; Te Whatu Ora - Health New Zealand, 2023b, 2023a). Research also indicates that young mothers experience stigmatisation and discrimination that they attribute to their age and/or ethnicity (Adcock, 2016; Makowharemahihi et al., 2014; Rawiri, 2007; Ware, 2019).
In discussion with researchers, discrimination was the topic that young mothers at He Puaawai Teen Parent Centre wanted to talk about. They shared a strong desire to see change in the way that doctors, nurses, and midwives service young parents and were passionate about ensuring that future young mothers had more support. Thus, in responding to their call, 22 parents, including two fathers attending (or recent school-leavers of) He Puaawai Teen Parent Centre volunteered to participate in this study. This qualitative kaupapa Māori study employed a series of wānanga, individual kōrero, and an investigator-triangulation thematic analysis. The research questions explored both the positive and negative healthcare experiences of this cohort during pregnancy, birth, and into motherhood.
The aim of this study was to listen and learn about the experiences of these young parents and co-design informational and/or educational materials to help healthcare practitioners better understand and support young mothers/parents. To spread awareness of the experiences of these young parents, the co-design materials and findings of this study were disseminated via various healthcare seminars and meetings around the Waikato region. The findings of this study contribute to previous research that revealed over the last 20 years young parents have continued to report predominantly negative experiences in their maternity journey. Participants of this study reported experiences of unsolicited judgement and advice, a general lack of manaakitanga (care, empathy, respect), communication, and support from doctors, nurses, and midwives. The relatively small number of positive experiences shared in this study emphasises the importance of manaakitanga regardless of age. An unexpected finding was the impact that receptionists had on young parents’ healthcare experiences, as the face and entry point of healthcare services.

year: 2024