Mapitio haya ya kimfumo yanachunguza jinsi constructed wetlands (CWs) zinavyofanya kazi kwa ufanisi katika kutibu maji taka yenye organic load kubwa kutoka uzalishaji wa maziwa na jibini, na chini ya hali gani za hydraulic zinafanya kazi kwa uthabiti zaidi. Watafiti walichagua tafiti 38 zilizopitiwa na wenzao zilizochapishwa kati ya 1995–2025 kwa kutumia mfumo wa PRISMA 2020; wakalinganisha kwa njia ya semi-quantitative uondoaji wa chemical oxygen demand (COD), five-day biochemical oxygen demand (BOD₅), total suspended solids (TSS), total nitrogen (TN) na total phosphorus (TP) pamoja na system configuration, hydraulic retention time (HRT), organic loading rate (OLR), climate, plants na filter materials.

Matokeo muhimu zaidi ya chanzo ni kwamba hybrid systems zinazounganisha vertical na horizontal subsurface-flow wetlands zilitoa mifano thabiti zaidi ya high performance miongoni mwa tafiti zilizochunguzwa. Katika synthesis ya review, median COD removal kwa hybrid systems iliripotiwa kuwa takribani %93 na BOD₅ removal takribani %94, huku total phosphorus removal kwa kawaida ikibaki katika %70–80. Faida hii inaelezwa kwa aerobic degradation na nitrification zinazosaidiwa na better oxygen transfer katika vertical-flow section, huku anoxic/anaerobic processes katika horizontal subsurface-flow section zikikamilishana katika treatment train ileile.

Review inasisitiza hasa kwamba high performance haitegemei system type pekee. Tafiti ambazo COD na BOD₅ removal zilikuwa juu ya %90 zilionekana mara nyingi zaidi katika VSSF systems ndani ya takribani 4–8 hours HRT (n = 4), na katika HSSF systems ndani ya 3–7 days HRT (n = 14). Katika sehemu ndogo ya comparative studies zilizoripoti OLR, kiwango cha mzigo wa chini ya 30 g COD m⁻² day⁻¹ kwa kila eneo (n = 7) kilihusishwa na operation thabiti zaidi. Katika loads za juu zaidi, baadhi ya tafiti ziliripoti kupungua kwa treatment performance hadi %25.

Nambari hizi si universal design limits. Assessment ya VSSF ilitengenezwa kutokana na tafiti nne tu na OLR threshold kutokana na tafiti saba tu, na watafiti hawakutumia formal correlation/regression test kwa uhusiano kati ya HRT au OLR na removal. Kwa hiyo, “operating envelope” ya review ni semi-quantitative synthesis ya engineering trends zinazojirudia katika tafiti tofauti; haithibitishi kwamba constructed wetland yoyote mpya itatoa removal zaidi ya %90 moja kwa moja ikiwa na HRT ya 4–8 hours au 3–7 days.

Matokeo mengine muhimu ya utafiti ni kwamba raw dairy-industry wastewater haipaswi kuingizwa moja kwa moja katika subsurface constructed wetlands nyingi. Chanzo kinatoa literature ranges pana kwa raw streams zinazofikia 80–95.000 mg/L kwa COD na 40–48.000 mg/L kwa BOD. Thamani hizi si composition ya kudumu ya wastewater moja; zinawakilisha streams tofauti kutoka whey, wash water na hatua tofauti za production. Baada ya pretreatment, chanzo kawaida kinatoa takribani 2000–5000 mg/L COD, 1000–2500 mg/L BOD na 250–600 mg/L TSS katika influent ya constructed wetland.

Kwa Türkiye, constructed wetlands zinaweza kuchunguzwa kama low-energy secondary au tertiary treatment option hasa kwa dairy, cheese na farm enterprises ndogo na za kati zilizo mbali na centralized treatment infrastructure. Hata hivyo, values za review si ready-made design recipe kwa Türkiye. Local dairy production process, whey ratio, fat na solids load, seasonal temperature, land requirement, pretreatment level, plant species, fill material, odor control na target effluent quality lazima zithibitishwe kwa separate engineering study.

Kwa nini dairy-industry wastewater ni tatizo maalum la treatment?

Dairy-processing wastewater si homogeneous water stream. Milk processing, cheese production, equipment na tank washing pamoja na cleaning operations zinaweza kuzalisha wastewater yenye chemical characteristics tofauti. Utafiti unasisitiza kwamba streams hizi zinaweza kuwa na kiwango kikubwa cha biodegradable organic matter, fat, protein, lactose, suspended solids, nitrogen na phosphorus.

Chanzo kinatoa literature information kwamba whey inayozalishwa katika cheese production inaweza kuwa takribani %85–95 ya volume ya original milk na inaweza kuhifadhi zaidi ya %50 ya nutrients zilizokuwa kwenye milk. Kwa hiyo, whey ikichanganyika bila control kwenye wastewater inaweza kuongeza organic load kwa kiwango kikubwa sana.

Table 2 ya chanzo inasisitiza hasa kwamba raw dairy-industry wastewater inaweza kuonyesha composition range pana sana:

Source note: Raw wastewater ranges zimekusanywa kutoka whey, CIP/wash waters na other production streams; hazipaswi kutafsiriwa kama simultaneous composition ya wastewater sample moja.

Kwa nini kuingiza raw whey moja kwa moja katika constructed wetland ni tatizo?

Subsurface-flow constructed wetlands zinategemea maji kupita ndani ya porous fill material. Very high suspended solids, fat na organic-matter loads zinaweza kusababisha pores kuziba kadiri muda unavyopita, hydraulic conductivity kupungua, na maji kutofuata designed flow path.

Review inajadili hasa kwamba katika high-load streams ambapo TSS ni zaidi ya takribani 1000 mg/L, risk ya rapid pore clogging katika upper substrate layers na hydraulic short-circuiting inaweza kuongezeka. Kwa hiyo, hatua kama screening, grease trap, sedimentation, Imhoff tank, dissolved air flotation, equalization, aerated pond au biological pretreatment zinaonekana mara kwa mara katika applications zilizochunguzwa.

Kulingana na assessment ya chanzo, role inayofaa zaidi ya constructed wetlands katika dairy-industry streams nyingi zenye load kubwa ni kuwa secondary au tertiary treatment stage inayopokea pre-treated water. Tofauti hii ni muhimu; kuona %98 COD removal katika full-scale example haimaanishi kwamba raw whey inaweza kuingizwa moja kwa moja katika bed hiyo hiyo.

Constructed wetland inatibu maji vipi?

Constructed wetland ni system tata zaidi kuliko process ya filter moja. Treatment hutokea kwa cooperation ya three main components:

• Substrate: Sand, gravel, zeolite, LECA au other porous materials hutoa mazingira ya physical filtration, surface retention na microbial biofilm.
• Plants: Root na rhizome system huathiri hydraulic structure na microenvironments; pia inaweza kuchangia uptake ya baadhi ya nutrients katika biomass.
• Microorganisms: Sehemu kubwa ya transformations kuu kama organic-matter degradation, nitrification na denitrification hufanywa na microbial communities.

Kwa sababu wetland types tofauti huunda oxygen na flow conditions tofauti ndani ya components hizi tatu, hazionyeshi behavior ileile kwa pollutants zilezile.

HSSF ni nini?

Horizontal subsurface flow constructed wetland (HSSF) ni system ambapo maji yanaingia upande mmoja wa bed na kusonga horizontally ndani ya fill material. Water surface kubaki kwa kawaida chini ya fill level kunaweza kutoa faida katika contact na odor control ikilinganishwa na systems zenye open-water surface.

Chanzo kinachukulia HSSF systems kama strong component kwa denitrification na baadhi ya nutrient-removal mechanisms kwa sababu ya low-oxygen au anoxic microenvironments. Pia long retention times na large bed volume zinaweza kutoa high hydraulic stability.

VSSF ni nini?

Vertical subsurface flow constructed wetland (VSSF) ni system ambapo wastewater huwekwa kwa kawaida kwa intermittent dosing juu ya bed na kusonga vertically kupitia fill material.

Bed kuweza kuwasiliana tena na air kati ya feeding cycles kunaweza kuongeza oxygen transfer. Kwa hiyo VSSF systems zinaweza kutoa faida katika aerobic degradation ya organic matter na nitrification ya ammonium. Review ina mifano ya VSSF iliyoripoti high BOD₅ removal katika shorter hydraulic retention times kama 4–8 hours.

Kwa nini hybrid system inajitokeza?

Hybrid constructed wetlands huunganisha vertical na horizontal-flow units katika treatment train moja. Hivyo redox conditions tofauti ambazo ni ngumu kuunda ndani ya bed moja zinaweza kutengenezwa sequentially.

Katika semi-quantitative synthesis ya review kwenye tafiti 38, hybrid systems ziliunda highest overall performance group zikiwa na takribani %93 median COD na %94 median BOD₅ removal. Total phosphorus removal iliripotiwa zaidi katika takribani %70–80.

Matokeo haya hayamaanishi kwamba “hybrid system ndiyo best system katika kila condition”. Systems zilizochunguzwa zilifanya kazi chini ya wastewater, climate, pretreatment, fill, plant na scale conditions tofauti. Hitimisho la waandishi ni kwamba katika heterogeneous literature, hybrid configurations zilionekana mara nyingi zaidi miongoni mwa high-performing examples.

Operating envelope inayopendekezwa na review ni ipi?

Values katika table hii si design regulation wala guaranteed optimum values. Review haikutoa formal dose–response model, regression au meta-regression kwa HRT na OLR. Watafiti waliunda engineering operating envelope kutoka performance trends zinazojirudia kati ya tafiti.

Nini hutokea OLR inapoongezeka?

Organic loading rate (OLR) ni organic-matter load inayofika kwenye unit wetland surface kwa unit time. Form inayotumika mara nyingi katika chanzo ni g COD m⁻² day⁻¹.

Review iliripoti kwamba loads zilizo juu ya 30 g COD m⁻² day⁻¹ katika baadhi ya systems zilionekana pamoja na kupungua kwa removal performance hadi %25 na higher likelihood ya operational problems. Waandishi wanaeleza kwamba katika literature hali hii mara nyingi huhusishwa na progressive substrate clogging na reduced oxygen transfer.

Hata hivyo, si kila included study ilipima mechanisms hizi moja kwa moja. Kwa hiyo uhusiano wa “high OLR + low performance” ulioonekana katika chanzo si single proven causal mechanism ya clogging katika systems zote.

Je, kuongeza HRT bila kikomo ni solution?

Hapana. Longer HRT inaweza kuongeza contact time kati ya pollutant na plant–substrate–microorganism system; lakini longer retention inahitaji larger land area au lower hydraulic capacity.

Review inajadili kwamba high removals katika HSSF huonekana mara nyingi ndani ya range ya 3–7 days, na beyond that additional HRT inaweza kutoa diminishing gain ikilinganishwa na extra land requirement. Kwa hiyo engineering objective si longest possible HRT, bali balanced operating point kati ya performance na land/hydraulic capacity.

Verianla Live: VSSF na HSSF comparison katika study ileile

Visible table hapa chini inaonyesha VSSF na HSSF results kutoka experiment ileile iliyowasilishwa katika Table 1 ya review kwa study ya Verma na Suthar. Structures zote mbili zililinganishwa chini ya HRT ya 5 days. Graph haipangi maximum values kutoka countries au laboratories tofauti dhidi ya kila moja.

Katika comparison hii, VSSF inatoa values za juu kuliko HSSF kwa BOD₅, COD, NH₄-N na phosphate removal, huku HSSF ikiwa juu kwa nitrate removal. Direction change hii inaendana na review approach kwamba oxygen/redox environments tofauti katika flow types hizi mbili zinaweza kutoa advantage kwa different nitrogen-transformation processes.

Hata hivyo, experiment hii moja si universal performance ratio kwa VSSF na HSSF systems zote.

Climate hubadilisha performance kiasi gani?

Katika review, temperature-dependent microbial slowing katika cold climates inaonekana kama factor muhimu. Katika examples za Germany na New Zealand, decreases za takribani %20–35 katika overall treatment performance ziliripotiwa wakati wa cold periods.

Katika tropical/subtropical conditions kama Brazil, Mexico, Philippines na Tunisia, baadhi ya systems zilizochunguzwa zilionyesha high COD na BOD₅ removal mwaka mzima. Katika milder regions kama Italy, Poland na Argentina, seasonal variability ilielezwa kuwa more visible.

Matokeo haya hayapaswi kutafsiriwa kama “warm climate ni nzuri, cold climate ni mbaya”. Plant species, bed depth, feeding regime, pretreatment na hydraulic design vinaweza kubadilisha ukubwa wa climate effect.

Fill material hufanya nini?

Traditional gravel hutumika katika sehemu kubwa ya studies kwa sababu ni cheap na widely available. Pia more porous au adsorptive materials kama zeolite, lightweight expanded clay aggregate (LECA), pumice na recycled construction materials zimechunguzwa.

Review ina examples kwamba alternative substrates zinaweza kuboresha hasa phosphorus retention na biofilm development. Katika Table 1, system iliyotumia LECA ilifikia %88,5 kwa total phosphorus; other systems zilizotumia recycled construction/demolition waste na stone-processing residues pia ziliripoti high phosphorus removal.

Matokeo haya hayathibitishi kwamba LECA au recycled aggregates ni superior kuliko gravel katika kila condition. Adsorption capacity inaweza kujaa kadiri muda unavyopita, na hydraulic behavior ya material lazima itathminiwe separately katika system scale.

Plant selection ni aesthetic decision tu?

Hapana. Review ilijumuisha Phragmites australis, Typha species, Canna indica, Cyperus alternifolius, Arundo donax na other macrophytes.

Mbali na nutrient uptake, plants zinaweza kuathiri root-zone structure, microbial habitat na oxygen distribution. Waandishi wanaeleza kwamba polyculture systems zenye zaidi ya species moja zinaweza kuongeza functional diversity na katika baadhi ya studies zilihusishwa na takribani %10–15 improvement katika nitrogen removal.

Hata hivyo, review haikufanya common controlled meta-analysis kati ya species, kwa hiyo haiwezi kuhitimisha “plant hii ndiyo best plant”. Uvumilivu kwa local climate na long-term maintenance ni muhimu angalau sawa na short-term removal percentage.

Constructed wetland inahitaji land area kiasi gani?

Chanzo kinatoa takribani 5–15 m² per population equivalent kama typical design magnitude kwa hybrid systems. Pia kinaeleza kwamba katika systems zilizounganishwa na aerated pond au anaerobic/other pretreatment, land requirement imeweza kupunguzwa kwa takribani %20–40 katika baadhi ya applications.

Values hizi za area hazipaswi kutumika kama direct sizing coefficient kwa dairy enterprises zote. Industrial flow, organic load na production regime zinaweza kutofautiana sana na “population equivalent” approach.

Kwa nini clogging huamua long-term performance?

Constructed wetland kutoa high removal katika miezi ya kwanza haimaanishi kwamba itadumisha hydraulic capacity ileile kwa miaka mingi. Accumulation ya solids, biomass na organic matter ndani ya fill inaweza kupunguza porosity.

Review inasisitiza kwamba kuna examples za 8–10 years long-term operation kwa some well-designed systems, lakini standardized sludge/solids-management protocols bado hazitoshi. Kwa hiyo hydraulic conductivity, surface ponding na organic-matter accumulation zinapaswa kufuatiliwa regularly.

Kwa nini odor issue haipaswi kusahaulika?

Readily biodegradable organic matter, fats na proteins katika dairy-industry wastewater zinaweza kuoza haraka wakati wa storage au under oxygen-free conditions. Chanzo kinaeleza kwamba malodorous compounds kama volatile fatty acids, ammonia na hydrogen sulfide zinaweza kutokea.

Kwa hiyo treatment design haiwezi kutegemea COD percentage pekee. Pretreatment, retention time, aeration–anoxic balance na land uses around the facility pia ni sehemu ya operational design.

Bibliometric analysis ilionyesha nini?

Figure 2 katika page 17 ya study inaonyesha co-occurrence network ya keywords katika publications 38, iliyotengenezwa kwa VOSviewer. “constructed wetland”, “wetlands”, “dairy wastewater” na “wastewater treatment” ziko katikati, huku concepts kama nitrogen, phosphorus, pollutant removal na subsurface flow zikitengeneza technical clusters zinazozizunguka.

Waandishi wanahitimisha kwamba studies za 1995–2010 zililenga zaidi basic removal performance, huku studies za 2018–2025 zikielekea hybrid configurations, alternative substrates, circular economy na nature-based-solution approach.

Weaker connections za terms kama “Sludge”, “climate”, “scalability” na “management” zinaashiria kwamba long-term operation, sludge management na climate resilience bado ni topics zilizounganishwa kidogo zaidi katika literature.

Kwa nini geographic analysis inapaswa kusomwa kwa tahadhari?

Figure 3 katika page 18 ya study inaonyesha global research distribution. Hata hivyo, percentages katika section hii hazilingani kikamilifu mathematically na count ya studies 38 katika chanzo.

Kwa mfano, text inatoa Greece na India kama %12,82. Katika Table 1, studies tano zinaonekana kwa kila nchi; 5/38 ni takribani %13,16. Thamani ya %5,13 iliyotolewa kwa countries zenye studies mbili inalingana na 2/39, na %2,56 kwa countries zenye study moja inalingana na 1/39. Katika paragraph ileile, Poland inarudiwa katika groups mbili tofauti za percentage.

Kwa hiyo, kwa Verianla, general conclusion kwamba research imejikita katika number ndogo ya countries imechukuliwa kuwa more reliable kuliko exact geographic percentages.

Matokeo muhimu yanayoungwa mkono na review

• Constructed wetlands ni nature-based treatment approach inayoweza kutoa high organic-matter removal kwa pre-treated dairy-industry wastewater kwa low external-energy demand.
• Hybrid VSSF–HSSF systems zimehusishwa mara nyingi na high COD na BOD₅ performance katika literature iliyochunguzwa.
• HRT na OLR ni miongoni mwa operational-control variables zinazoripotiwa mara nyingi zaidi kwa treatment performance.
• Kwa sababu ya high solids na organic load, raw milk/cheese wastewater haifai kwa subsurface systems nyingi bila pretreatment.
• Substrate porosity, plant diversity na climate vinaweza kuathiri long-term performance.
• Alternative na recycled fill materials ni options zinazostahili research kwa phosphorus retention na circular economy.
• Long-term clogging, maintenance, sludge management na cold-climate performance bado ni major research gaps.

Matokeo ambayo review haijathibitisha

• 4–8 hours VSSF au 3–7 days HSSF HRT si exact optimum design kwa facilities zote.
• 30 g COD m⁻² day⁻¹ si universal failure au regulatory limit.
• Hybrid constructed wetland si universal solution iliyothibitishwa kuwa superior kuliko single-stage systems katika conditions zote.
• Removal percentages kutoka studies tofauti hazitoki katika same initial wastewater na experimental protocol.
• Low energy demand ya constructed wetland haiondoi land, maintenance na pretreatment requirements.
• Compliance ya treated water na specific reuse au discharge standard haiwezi kuamuliwa kwa removal percentage pekee.
• Operating envelope iliyopendekezwa katika review si design standard iliyothibitishwa kwa formal meta-regression au common controlled experiment.

Mbinu na Matokeo ya Utafiti

Systematic search ilifanywaje?

Watafiti walitafuta kipindi cha Januari 1995–Aprili 2025 katika databases za Scopus, Web of Science na Google Scholar.

General search structure imetolewa katika chanzo kama ifuatavyo:

(constructed wetland OR artificial wetland OR wetland treatment) AND (dairy wastewater OR dairy effluent OR dairy industry wastewater OR cheese whey OR whey wastewater)

Kuongeza terms “Cheese whey” na “whey wastewater” kulilenga kukamata katika search hasa studies zinazohusu high-concentration waste streams katika cheese production.

PRISMA selection process

Katika initial database search, records 65 zilitambuliwa. Baada ya preliminary screening, duplicate removal, record screening, full-text assessment na eligibility checks, studies 38 ziliingizwa katika final systematic review.

Figure 1 katika page 3 ya chanzo inaonyesha process hii kwa PRISMA 2020 flow diagram. Diagram kuonyesha visibly records ziliondolewa katika hatua gani ni mojawapo ya methodological strengths za study ikilinganishwa na previous narrative reviews.

Inclusion criteria

Ili study iingizwe, ilihitajika:

• kutathmini moja kwa moja treatment ya dairy-industry au dairy-farm wastewater kwa constructed wetland,
• kuripoti quantitative removal performance kwa angalau moja ya COD, BOD₅, TSS, TN au TP,
• kutoa sufficient technical information kwa comparison kama system configuration, scale, plant au substrate

.

Non-peer-reviewed primary studies, applications zisizo dairy-industry wastewater, studies zisizotumia constructed wetland kama main process, studies zisizoripoti quantitative performance kwa core parameters, na duplicate datasets zisizoweza kutenganishwa ziliondolewa.

Study iliondolewa ikiwa HRT au OLR haipo?

Si kila mara. Watafiti walitoa HRT na OLR pale ziliporipotiwa wazi. Kutokuwepo kwa OLR hakukusababisha study kuondolewa automatically kutoka full dataset.

Badala yake, katika specific HRT/OLR comparisons, study isiyo na operational data inayohitajika iliachwa nje ya quantitative comparison husika lakini ikahifadhiwa katika overall literature table.

Approach hii inalenga kuhifadhi evidence base huku ikizuia specific engineering comparisons kufanywa kwa false precision.

Ni variables gani zilitolewa?

Kwa kila study, geographic context, Köppen–Geiger climate class, HSSF/VSSF/hybrid/FWS configuration, laboratory–pilot–full-scale information, plant species, substrate na bed depth, HRT, OLR ikiwa available, na COD/BOD₅/TN/TP/TSS removals zilirekodiwa.

Study ikiwa na multiple operating conditions, watafiti wanaripoti kwamba walikokotoa weighted averages kwa flow rate au HRT. Removals zilinormalize kuwa percentage kwa comparability.

Je, study hii ni meta-analysis?

Hapana. Ingawa study inatumia systematic search na selection method, haifanyi formal meta-analysis au meta-regression.

Waandishi walitengeneza descriptive summaries kama mean, range na standard deviation kwa configurations; na walitathmini uhusiano wa HRT na OLR na performance kwa repeated relationships na trends kati ya studies badala ya formal statistical correlation tests.

Kwa hiyo statement “performance huongezeka OLR ikiwa chini ya 30” si controlled causal threshold experiment, bali common trend inayoonekana katika compiled literature.

Robustness check ilifanywaje?

Watafiti walitathmini upya main trends kwa kuondoa studies nne katika robustness check pekee. Studies hizi zilibaki katika overall dataset ya 38.

• Galve na wenzake [34]: iliripoti unusual percentage changes kwa NO₂⁻/NO₃⁻ badala ya standard removal.
• Idris na wenzake [45]: HRT haikuripotiwa.
• Newman na Clausen [52]: HRT haikuripotiwa.
• Mohammed na Ismail [54]: ilitoa modeling-based results badala ya quantitative removal.

Iliripotiwa kwamba kuondoa studies hizi nne hakubadilisha main trends kuhusu configuration, HRT na OLR.

Risk-of-bias assessment

Kwa sababu studies zilionyesha strong heterogeneity katika scale, system type, operating conditions, measured variables na reporting detail, standardized quantitative risk-of-bias tool haikutumika.

Badala yake, method transparency, consistency ya removal values, completeness ya operational data na study objective–result alignment vilitathminiwa qualitatively. Uamuzi huu umeelezwa wazi katika methods section; hata hivyo, bila formal quality score, effect ya low- na high-methodological-quality studies kwenye synthesis haiwezi kutenganishwa quantitatively kikamilifu.

OSF registration

Systematic review ilisajiliwa kwenye Open Science Framework kwa transparency na reproducibility. Chanzo kinatoa registration address https://osf.io/4f8av na access date ya 6 Januari 2026.

Matokeo ya msingi

Hybrid VSSF–HSSF structures zilijitokeza katika review zikiwa na median COD takribani %93 na BOD₅ takribani %94. VSSF systems zilionyesha strong results kwa aerobic organic-matter removal na nitrification katika short HRT, huku HSSF systems zikionyesha strong examples kwa longer hydraulic contact, suspended-solids removal na baadhi ya nutrient transformations.

Katika compiled evidence, high removal ilionekana mara nyingi zaidi katika 4–8 hours kwa VSSF, 3–7 days kwa HSSF, na conditions chini ya 30 g COD m⁻² day⁻¹ kwa OLR. Hata hivyo, kwa kuwa evidence counts ni n = 4, n = 14 na n = 7 mtawalia, limits hizi zinahitaji cautious interpretation hasa kwa VSSF na OLR.

Data na citation problems ndani ya chanzo

Ingawa systematic method ni strong, kuna visible inconsistencies kati ya data table ya review na bibliography yake.

Ref. 45 inconsistency: Katika Table 1, row ya Australia/Idris et al. [45] imeonyeshwa kama “Dairy factory wastewater”. Hata hivyo, title ya Ref. 45 katika references ni “Evaluation of the giant reed (Arundo donax) in horizontal subsurface flow wetlands for the treatment of recirculating aquaculture system effluent”. Kwa visible title, study inahusu aquaculture effluent, si dairy industry. Kwa kuwa inclusion criterion ya study ilihitaji dairy-industry wastewater pekee, matching hii inaleta important internal-source problem.

Ref. 24 geography inconsistency: Section 5.2 inaunga mkono pilot applications nchini Australia kwa “[24]”. Ref. 24 katika references ni dairy-industry study ya Kotsia na wenzake nchini Greece.

Ref. 44 author inconsistency: Katika Table 1, Ref. 44 imeandikwa “Italy/Gorra et al.”, huku Ref. 44 katika bibliography imeandikwa na Cap, Freppaz, Zanini na Scalenghe. Title ya study inalingana na constructed-wetland application ya dairy wastewater katika mountainous region nchini Italy; lakini author label hailingani na bibliography.

Bibliometric percentage inconsistency: Review inasema ina studies 38. Hata hivyo, geographic distribution inatumia %12,82 kwa studies tano, %5,13 kwa studies mbili na %2,56 kwa study moja. Ratios hizi zinahusiana na denominator ya studies 39. Pia Poland imerudiwa katika both %5,13 na %2,56 groups katika paragraph ileile.

Chanzo hakijafanya re-analysis ya kiwango ambacho yoyote ya problems hizi inabadilisha main HRT/OLR results. Kwa hiyo Verianla article haijasahihisha maeneo haya kimya kimya na hasa haijatumia bibliometric percentages kama main engineering result.

Interpretation kuu ya kisayansi

Hitimisho linaloweza kutetewa zaidi la study ni kwamba constructed wetlands kwa dairy-industry wastewater si passive ponds za plants pekee, bali ni biological–hydraulic treatment systems ambapo HRT, organic load, flow direction, oxygen regime, substrate na plant lazima zidesigniwe pamoja.

High performance ya hybrid configurations ina strong engineering rationale kwa sequential use ya biochemical environments tofauti. Kwa upande mwingine, operating envelope bado imetokana na limited number ya heterogeneous field/laboratory studies. Future work inahitaji common reporting standards, longer-term field validation, cold na arid climate data, clogging/sludge management na formal quantitative syntheses.

Dokezo la Chanzo na Mbinu

Jina kamili la utafiti asilia: Constructed Wetlands as a Nature-Based Solution for Treating Industrial Dairy Wastewater: A Review

Waandishi na mpangilio wao: Brenda Suemy Trujillo-García; Mayerlin Sandoval-Herazo; Jacel Adame-García; Oscar Marín-Peña; Graciela Nani; Joaquín Sangabriel-Lomelí; Lidilia Cruz-Rivero; Luis Carlos Sandoval-Herazo.

Co-first/equal contribution: Chanzo hakina declaration ya co-first authorship.

Waandishi wanaowajibika: Mayerlin Sandoval-Herazo na Joaquín Sangabriel-Lomelí.

Taasisi: Tecnológico Nacional de México / Instituto Tecnológico Superior de Misantla, Mexico; Universidad de Sucre, Colombia; Tecnológico Nacional de México / Instituto Tecnológico de Úrsulo Galván, Mexico; Instituto Tecnológico de Tantoyuca, Mexico.

DOI: 10.3390/environments13030133

Jarida: Environments.

Mchapishaji: MDPI, Basel, Switzerland.

Juzuu / toleo / nambari ya makala: Volume 13, Issue 3, Article 133.

Aina ya chanzo na peer-review status: Ni peer-reviewed systematic review article. PRISMA 2020-based systematic search na semi-quantitative synthesis zimetumika; formal meta-analysis haikufanywa.

Academic editor: Chin H. Wu.

Tarehe za makala: Received 5 January 2026; Revised 17 February 2026; Accepted 24 February 2026; Published 1 March 2026.

Official DOI link:https://doi.org/10.3390/environments13030133

Official publication link:MDPI — Environments article page

License: Creative Commons Attribution (CC BY).

Funding: Waandishi waliripoti kwamba research haikupokea external funding.

Data availability: Waandishi wanaeleza kwamba hakuna new data iliyotengenezwa au kuchambuliwa katika systematic review hii.

Conflict of interest: Waandishi walitangaza kwamba hakuna conflict of interest.

Author contributions: Conceptualization na writing—review & editing: B.S.T.-G., L.C.S.-H. na J.S.-L.; validation na data curation: M.S.-H.; supervision: G.N. na O.M.-P.; methodology: L.C.-R. na J.A.-G. Imeelezwa kwamba waandishi wote walisoma na kuidhinisha published version.

Systematic-review method: Databases za Scopus, Web of Science na Google Scholar zilitafutwa kwa kipindi cha Januari 1995–Aprili 2025; clear Boolean search structure kuhusu constructed wetlands na dairy-industry wastewater ilitumika. PRISMA 2020 selection process iliingiza peer-reviewed primary studies 38 katika final synthesis.

OSF registration: Registration address ya systematic review imeonyeshwa katika chanzo kama https://osf.io/4f8av.

Quantitative-synthesis limit: Kwa sababu studies zilikuwa strongly heterogeneous, formal meta-analysis, meta-regression au HRT/OLR–performance correlation test haikufanywa. Relationships zilitolewa kwa semi-quantitative synthesis inayotegemea repeated between-study trends.

Risk-of-bias limit: Standardized quantitative risk-of-bias tool haikutumika. Methodological transparency, data completeness, consistency ya removal values na objective–result alignment vilitathminiwa qualitatively.

Operating-envelope limit: Result ya 4–8 hours HRT kwa VSSF inategemea n = 4, result ya 3–7 days kwa HSSF inategemea n = 14, na result ya OLR <30 g COD m⁻² day⁻¹ inategemea n = 7 studies. Ranges hizi si universal design standard au guaranteed optimum condition.

Ref. 45 internal-source inconsistency: Table 1 inatoa Ref. 45 kama dairy-factory wastewater application nchini Australia, huku title ya number hiyo hiyo katika bibliography ikihusu recirculating aquaculture-system effluent. Haiwezekani kuamua kwa uhakika kutoka source text ni record ipi ina kosa.

Ref. 24 internal-source inconsistency: Section 5.2 inatumia Ref. 24 kwa Australia application; Ref. 24 katika bibliography ni dairy-industry study ya Kotsia na wenzake nchini Greece.

Ref. 44 internal-source inconsistency: Table 1 inaandika “Gorra et al. [44]”, huku Ref. 44 katika bibliography ikiwa Cap, Freppaz, Zanini na Scalenghe.

Bibliometric consistency note: Baadhi ya percentages katika geographic-distribution section hazilingani mathematically na dataset ya studies 38 na Poland imerudiwa katika percentage groups mbili. Ratios hizi hazijasahihishwa kimya kimya na Verianla.

Scientific-source limit: Treatment performances, HRT/OLR ranges, substrate na plant assessments, climate effects na engineering recommendations katika Verianla article hii zinategemea tu results zilizoripotiwa na systematic review iliyochunguzwa. External sources hazikutumika kuongeza new scientific results; zilitumika tu kwa bibliographic verification ya publication identity na peer-review information.