Reusing Grey Water to Lower Temperatures in the Mediterranean Basin Cities

The Mediterranean region is a hot spot for climate change, and cities of this area will be exposed to both increasing temperatures and decreasing precipitations. Green Infrastructures (GIs) can lower urban temperatures through evapotranspiration with an adequate soil moisture content. Grey water reuse can both guarantee the right soil moisture content and reduce freshwater exploitation. In order to test the effectiveness of soil moisture on reducing air temperature, two modelling simulations ran with the microclimate CFD-based model ENVI-met 4.0. The chosen day was a registered heat wave (7 July 2019) in Lecce, a city of south Italy, which was selected as case study for the Mediterranean area. The results demonstrated the effectiveness of soil moisture on evapotranspiration in reducing air temperature. From a circular economy perspective, the supply of grey water for urban GIs represents a strategic adaptation strategy to the expected effects of climate change on the Mediterranean basin.

Different Approaches to Assessing Pollution Load: The Case of Nitrogen-Related Grey Water Footprint of Barley and Soybean in Argentina

Agriculture is among the main causes of water pollution. Currently, 75% of global anthropogenic nitrogen (N) loads come from leaching/runoff from cropland. The grey water footprint (GWF) is an indicator of water resource pollution, which allows for the evaluation and monitoring of pollutant loads (L) that can affect water. However, in the literature, there are different approaches to estimating L and thus contrasting GWF estimates: (A1) leaching/runoff fraction approach, (A2) surplus approach and (A3) soil nitrogen balance approach. This study compares these approaches for the first time to assess which one is best adapted to real crop production conditions and optimises GWF calculation. The three approaches are applied to assess N-related GWF in barley and soybean. For barley in 2019, A3 estimated a GWF value 285 to 196% higher than A1, while in 2020, the A3 estimate was 135 to 81% higher. Soybean did not produce a GWF due to the crop characteristics. A3 incorporated N partitioning within the agroecosystem and considered different N inputs beyond fertilization, improving the accuracy of L and GWF estimation. Providing robust GWF results to decision-makers may help to prevent or reduce the impacts of activities that threaten the world’s water ecosystems and supply.

Penyisihan Material Organik dan Nitrogen dengan Proses Aerasi Menggunakan Microbubble Generator (MBG) pada Instalasi Pengolahan Air Limbah (IPAL) Asrama

Sebuah Instalasi Pengolahan Air Limbah (IPAL) di asrama mahasiswi UGM, Yogyakarta memiliki unit reaktor yang terdiri dari ekualisasi, aerasi 1, aerasi 2 dan clarifier dengan proses aerasi secara intermiten menggunakan Microbubble Generator (MBG) dengan fase aerasi dan tanpa aerasi masing-masing selama 15 menit. IPAL tersebut dibangun sebagai upaya dalam memenuhi standar Green Building bagi bangunan lama asrama di UGM untuk mengolah air limbah grey water. Hasil olahan air limbah akan dimanfaatkan di lingkungan asrama. Selama 208 hari beroperasi, kajian mengenai performa IPAL belum pernah dilakukan. Oleh karena itu, diperlukan kajian untuk mengetahui performa dan konsumsi energi pada IPAL dalam menyisihkan parameter pencemar berupa COD, nitrogen dan fosfat. Kajian dilakukan selama 81 hari pengamatan dengan menguji parameter kualitas air limbah pada setiap unit pengolahan. Parameter COD dan amonia telah memenuhi baku mutu Peraturan Menteri Lingkungan Hidup dan Kehutanan No. 68 Tahun 2016 tentang Baku Mutu Air Limbah Domestik, sedangkan parameter fosfat masih belum memenuhi baku mutu Peraturan Daerah D.I.Y. No.7 Tahun 2016 mengenai kegiatan IPAL Komunal. Hasil pengamatan pada performa IPAL, menunjukkan kedua tangki aerasi memiliki performa yang hampir sama, namun keberadaan tangki aerasi 2 tidak memiliki pengaruh yang signifikan dalam menyisihkan parameter pencemar. Pada tangki aerasi 1, efisiensi penyisihan COD mencapai rata-rata sebesar 73,6±17,46%, penyisihan PO4-P sebesar 39,12±14,96%, penyisihan total nitrogen sebesar 56,15±19,6%, efisiensi nitrifikasi sebesar 73,1±20.07% dan efisiensi denitrifikasi sebesar 61,72±27,48%. Total konsumsi energi pada IPAL dengan proses aerasi intermiten, dengan debit rerata 537,84 l/hari sebesar 14,12 kWh/m3 dan biaya sebesar Rp. 20.414/m3. Urutan konsumsi energi terbesar adalah penyisihan fosfat sebesar 5,10 kWh/gPO4-P, kemudian penyisihan amonia sebesar 1,79 kWh/gNH3-N, penyisihan TN sebesar 1,95 kWh/gTN dan penyisihan COD sebesar 0,45 kWh/gCOD. ABSTRACTA Wastewater Treatment Plant (WWTP) in the student dormitory of UGM, Yogyakarta has a reactor unit consists of an equalization, aeration 1, aeration 2, and clarifier with intermittent aeration process using a Microbubble Generator (MBG) with or without aeration for 15 minutes each. The WWTP was built as an effort to meet the Green Building standards for the old dormitory at UGM to make better process of grey water. The processed wastewater will be used for the dormitory environment. Operated for 208 days, there was no former studies for the WWTP. Therefore, a study is needed to determine performance and energy consumption of the WWTP in removing pollutant parameters consisting of COD, nitrogen and phosphate. The study was carried out for 81 days of observation by testing the wastewater quality parameters in each treatment unit. COD and ammonia parameters have met the quality standards of the Regulation of the Minister of Environment and Forestry No. 68 of 2016 concerning Domestic Wastewater Quality Standards, while phosphate doesn’t meet the quality standards of Regional Regulation D.I.Y. No. 7 of 2016 concerning Communal WWTP Activities. Results shows the performance from two aeration tanks are almost the same, but the existence of aeration tank 2 doesn’t have a significant effect. The results in aeration tank 1 showed the COD removal efficiency reached an average of 73.6±17.46%, PO4-P removal 39.12±14.96%, total nitrogen removal 56.15±19.6%, the nitrification efficiency 73.1±20.07% the denitrification efficiency 61.72±27.48%. The total energy consumption with intermittent aeration process with an average discharge of 537.84 l/day is 14.12 kWh/m3 and a cost of Rp. 20,414/m3 with the largest energy use being phosphate removal at 5.10 kWh/gPO4-P, then ammonia removal at 1.79 kWh/gNH3-N, TN removal at 1.95 kWh/gTN and COD removal at 0.45 kWh/gCOD.

Virtual nitrogen and phosphorus flow associated with interprovincial crop trade and its effect on grey water stress in China

The grey water footprint (GWF) is defined as freshwater requirements for diluting pollutants in receiving water bodies. It is widely used to measure the impact of pollutant loads on water resources. GWF can be transferred from one area to another through trade. Although pollution flow has previously been investigated at the national level, there has been no explicit study on the extent to which crop trade affects GWF across regions and the associated changes in grey water stress (GWS). This study analyzes pollution flow associated with interprovincial crop trade based on nitrogen (N) and phosphorus (P) loss intensity of three major crops, namely, maize, rice and wheat, which is simulated by a grid-based crop model for the period 2008–2012, and evaluates the spatial patterns of GWS across China. The results indicate that the integrated national GWF for N and P was 1,271 billion m3 yr-1, with maize, rice, and wheat contributing 39%, 37%, and 24%, respectively. Through interprovincial crop trade, southern China outsourced substantial N and P losses to the north, leading to a 30% GWS increase in northern China and 66% GWS mitigation in southern China. Specifically, Jilin, Henan, and Heilongjiang Provinces in the north showed increases in GWS by 161%, 114%, and 55%, respectively, while Fujian, Shanghai, and Zhejiang in the south had GWS reductions of 83%, 85%, and 80%, respectively. It was found that the interprovincial crop trade led to reduced national GWF and GWS. Insights into GWF and GWS can form the basis for policy developments on N and P pollution mitigation across regions in China.